Preface
This Guide has been developed for customers of Winter Panel Corporation to assist in the proper use and installation of Curtainwall and Structurewall™ panels on timber frame houses. While these techniques and details have generally been thoroughly tested and shown to work well, Winter Panel Corporation recognizes that new and better techniques for installing stresskin panels are frequently developed by builders. We would greatly appreciate comments on this guide and suggestions for improvements in future editions. Please address comments and suggestions to Sales Dept., Winter Panel Corporation, RR 5, Box 168B, Brattleboro, VT 05301. Thank you very much.
This guide is not designed for beginners or novice carpenters. It presupposes that the reader already has a basic understanding of sound construction practices, including job site safety and proper use of power tools. Working with stresskin panels requires the use of large and potentially very dangerous power tools. Winter Panel Corporation urges all builders to use care when installing stresskin panels and to keep safety a foremost concern on the job site.
Copyright © 1988-2005, by Winter Panel Corporation, Inc. All rights reserved. No part of this publication may be reprinted or reproduced, in whole or in part, without the written permission of Winter Panel Corporation. Revised June 11, 1997.
Table of Contents
Winter Panel Corporation's stresskin panels are ideal for enclosing timber-frame houses. Curtainwall panels (with drywall as the inner skin and waferboard or oriented strand board (OSB) as the outer skin) may be used for some wall and most applications. They provide insulation, wall and roof sheathing and a finished interior drywall surface.
Structurewall panels, with waferboard or OSB as both inner and outer skins, should be used where a sturdy nail base is required, or where additional strength is needed. They are often used in kitchens to support hanging wall cabinets and at roof edges where long overhangs are desired. They are also required for roofing in situations with unsupported spans over 4'. With Structurewall panels, an interior wall surface such as drywall must be applied to provide a full 15-minute fire rating.
This guide covers the basics of stresskin panel installation on timber frames. For additional information, or for clarification of material presented in this manual, contact Winter Panel Corporation.
Panels arrive at your building site wrapped in a protective covering. This will fully protect panels during shipment, but it may not provide full protection at your building site. Once the panels arrive, it is your responsibility to make sure that they are protected from moisture and other damage. Panels should be kept off the ground with blocking as shown in Figure 1 and remain fully protected until use. If the panels are not going to be installed right away, they should ideally be stored under cover in a barn or shed.
|
Figure 1. Storage of Panels. If panels are to be installed quickly, within a few days to a week, keep them stacked in the shipping bundles on blocking spaced no more than 4' o.c. Make sure they are on flat ground and fully protected from rain. Additional protection from rain may be required if the shed-pack has been damaged in shipping or unloading. If the panels will not be installed quickly, it is better to store them in a shed or barn.
|
Make sure the stacks or bundles of panels are stored flat. The blocking supporting them should be on level ground or a floor so that the panels are not at all twisted.
The panels are quite heavy, so you may want to clear an area near the building site for unloading to minimize moving them around later. Enclosing an average timber-frame house with stresskin panels will usually take from four to six days with a skilled crew. It will take longer if you are not familiar with panel installation or if the house is very large.
Avoid excessive exposure of panels to rain. If possible, plan around local weather forecasts and install panels when a several-day stretch of dry weather is expected. Curtainwall panels will withstand several wetting and drying cycles, providing they do not stay wet and are not moved while they are wet. If panels are allowed to remain wet, the paper on the drywall may mildew and swelling of both drywall and waferboard edges may occur. If panels are moved while wet, the paper on the drywall may peel off. Structurewall panels are more resistant to moisture.
Curtainwall Stresskin panels are non-structural when installed on timber-frame buildings. While panels will stiffen the frame and provide some racking support, most of the strength still comes from the frame itself. The major considerations when installing panels should be ease of installation, ease of interior finishing and minimizing panel waste. Usually this means having as many panel edges as possible resting on framing members.
Wall panels can be installed either vertically or horizontally. They are usually installed vertically, spanning from the sill to a girt or plate. Depending on the frame design, however, it often makes sense to apply some panels horizontally as shown in Figure 2.
|
Figure 2. Wall Panel Installation. Panels can be installed either vertically or horizontally depending on the framing system used.
|
Where panel edges align with framing members, they should be nailed or screwed into the wood. Panel edges not supported by a framing member are joined with splines. From a structural standpoint, it is not necessary that vertical panel edges align with posts, but doing so will simplify interior finishing by eliminating exposed drywall joints.
To optimize material use and simplify your work with stresskin panels, it helps to plan ahead when you design your frame. Try to have as many panel joints align with framing members as possible.
Roof panels may be applied with the long dimension oriented either parallel or perpendicular to the roof ridge, depending on the timber framing system used. If a rafter-purlin system is used, with purlins 4' on-center (o.c.) spanning major rafters as shown in Figure 3, the panels should be applied parallel to the roof ridge. Ends of panels are secured to rafters, while purlins support the side edges.
If a rafter-only framing system is used with rafters 4' o.c., as shown in Figure 4, panels are usually run perpendicular to the roof edges with side edges supported on rafters.
Roof panels must be installed with both side edges supported on framing members. Allow at least l½" of bearing surface on the wood Whenever possible, the panel ends should also rest on framing members (see Figures 3 and 4). In an ideally framed roof, all four edges of each panel will be supported by timbers. This will leave no exposed edges on the interior, and no drywall taping will be required.
|
Figure 3. Rafter-Purlin Roof Framing. With major rafters and 4' o.c. purlins spanning them, install panels parallel to the roof ridge.
|
|
Figure 4. Rafter-Only Roof Framing. With rafters 4' o.c., run panels perpendicular to the roof edge.
|
Use the longest panels possible in enclosing a roof, but make sure you take into account the ease of installation. The longest panels are only practical when a crane is being used for installation. Curtainwall panels up to 16' long and Structurewall panels up to 24' long are available. Staggering the panels to offset joints is not required.
Roof panels overlap or overhang wall panels at both the eaves and gable ends. Overhangs of up to 12" are allowable with Curtainwall panels; Structurewall panels may overhang up to 24". These limits assume that the overhanging panel spans a rafter bay or extends at least 4' back on the roof. For narrow panel sections at the roof edge, the overhang should not exceed the amount of panel that is supported.
There are two types of panel joints commonly used with stresskin panels on timber-frame houses: butt joints, and dual 5/8 x 3" spline joints. A 2x4 spline may also be used as reinforcement for a particularly long unsupported wall span (over 9'). The simplest is the butt joint. When two panels meet at a framing member, the edges of both panels are secured to it as shown in Figure 5. This is the best type of joint in terms of thermal performance and ease of interior finishing.
Figure 5. Butt Joints Over Framing Members. Try to have panel joints align with framing members whenever possible. This produces the best joint in terms of energy-efficiency and ease of interior finishing. At least 1½" of the panel must rest on the timber for adequate attachment.
For the most energy-efficient seal with butt joints, leave a ¼" gap between the panels. After all panels have been installed, go back and fill these gaps with foam sealant (see Section 19).
All panel joints that do not align with framing members must be reinforced with inset splines. Splines fit into routed channels in the panel edges (see the following section for routing instructions). Inset dual 5/8 x 3" plywood splines, as shown in Figure 6, are recommended for most unsupported panel joints. To assure a tight seal, fill a special foaming channel with expanding foam sealant after panels are installed. Panels can be ordered pre-routed for the 5/8 x3" splines and foaming channel.
|
Figure 6. 5/8 x 3" Plywood Spline Joint. Dual 5/8 x 3" plywood splines are recommended for joining both wall and roof panels. By applying foam sealant in the foaming channel, you produce an extremely energy-efficient joint.
|
In order to simplify installation, the 5/8 x 3" splines may be inset into one side of the joint as shown in Figure 6 (top) before setting the panel in place. Alternately, the splines may be slid in from the top or side after panels are abutted, but before the second panel is secured to the frame. Whichever technique is being used for installing splines, foam sealant must be applied in the foaming channel after panels are abutted. This is described in Section 4a below. Nail or screw through the panel skins into plywood splines 8" o.c. Use 6d galvanized nails or 1¼" galvanized drywall screws for the exterior, and ring-shank drywall nails or standard drywall screws for the interior. If possible, use only galvanized fasteners. We recommend using air-gun nails or screws.
2x4 splines can also be used for unsupported panel joints. For most panel joints, the 5/8 x 3" plywood splines are recommended, but for long spans (over 9'), 2x4 splines are required because of their greater strength. For a 2x4 spline joint, foam is routed out to a depth of ¾" on each adjoining panel edge. The skins are secured to the spline as shown in Figure 7. A bead of caulk where the waferboard skins abut will help seal the joint tightly.
If using a 2x4 spline joint with panels that have been pre-routed for the dual plywood splines, there will be deeper grooves at the corners of the 2x4 rout. These have to be filled with foam sealant as the 2x4 splines are installed. For this reason, if you are using 2x4 spline joints, it is better to order un-routed (square edge) panels.
Figure 7. 2x4 Spline Joint. For a 2x4 spline joint, remove ¾" of foam from the edge of each panel. The extending waferboard and drywall skins are secured to the spline with nails or screws as shown. Apply a bead of caulk where the waferboard skins will meet for a tight joint.
If possible, use galvanized fasteners throughout, both on the exterior and interior. There may be significant moisture sources in the house, especially as the timber frame is drying out. Moisture moving through the panel joints can cause non-galvanized fasteners to rust. In some cases, the rust can bleed though the joint compound and paint on the interior, staining the wall.
4a. Sealing Panel Joints With Foam
When panels abut over a framing member, the best technique is to leave a ¼" gap and fill it later with expanding foam sealant. With the dual plywood splines, the foaming channel should be filled with sealant after all nails and/or screws are applied to the panels and splines. Holes 3/8' in diameter are drilled at the panel joints through the spline and into the foam channel.
The holes should be spaced approximately 1' apart. Foam sealant is then injected into the foam channel and allowed to expand to seal the panel joint.
As described previously, there are two ways to install splines: either they can be inserted into one panel before the panels are joined, or the panels can be abutted and then the splines slid in from the end or top. With either technique, though, you will apply the bead of foam sealant after sliding the panels together.
Stresskin panels can be cut with large-diameter circular saws. Winter Panel Corp. offers a 16" saw with carbide blade for sale or rent; this saw works very well for most cuts. This saw has a 6-3/16" depth of cut at 90° and 4-3/16" at 45°. For miter cuts less than about 50°, you will have to finish the cut with a handsaw. A handsaw is also required for finishing corner cuts around windows and doors.
For certain corner joints and roof panel details, you may need to cut through one skin and the foam, leaving the other skin intact to provide an overlap. To make this cut, set the cutting depth to approximately 4" (so it does not quite reach the lower skin). The foam and upper skin can be broken off and any extra foam easily removed with a paint scraper. Depending on the application, the foam on this edge may also have to be routed out (see below).
Routing of panel edges is required wherever spline joints are to be used, and where 2x4s will be inset for reinforcement at wall corners, door and window openings, roof edges and various other locations described in this manual. For dual 5/8 x 3" spline joints, two parallel grooves are cut in the foam next to the inner and outer skins to a depth of 1½", and a special foaming channel is cut into the foam between the two spline grooves. Panels are available pre-routed for these grooves.
For a 2x4 spline joint, the foam is routed out ¾" on each of the panel edges to be joined. For a fully-inset 2x4 (around door and window openings, at wall corners, etc.), 1½" of foam is routed out from the panel edge.
Special router bits for these different applications are available for rent or purchase from Winter Panel Corp. Always rout the panels before setting them on the frame. Operate the router from the waferboard side to minimize damage to, or scarring of, the drywall. Try to do your routing in a clear area with plenty of room to maneuver as shown in Figure 8. Use goggles and a dust mask for safety.
|
Figure 8. Routing Panels. Always wear eye protectors and a dust mask when routing panels. Rout panels from the waferboard side to avoid damaging or scarring the drywall.
|
Wherever any portion of a panel rests on a framing member — post, girt, plate, brace, rafter, purlin, etc.— it should be securely attached with nails or screws from the outside. Either spiral "ardox" nails or hardened steel screws should be used with stresskin panels. For hardwood frames, allow 1½" penetration. With softwood frames, allow 2½" nail penetration (7" nails) or 1½" screw penetration. Hot-dipped galvanized fasteners are recommended to protect from rust and provide better holding power.
Panel edges must rest a minimum of 1½" on the framing members for secure attachment. Along panel edges, fasteners should be set 1" – 2" in from the panel edge and spaced 8" o.c. as shown in Figure 9. For ease in installation, they can be driven about halfway through the panel before the panel is set in place.
Figure 9. Panel Attachment to Frame. Allow 1½" nail or screw penetration into hardwood frames. For softwood frames, allow 2½" nail penetration or 1½" screw penetration. Use 8" on center spacing at panel edges and 12" o.c. spacing where the midpoint of a panel rests on a framing member.
When the midpoint of a panel rests on a framing member or brace, nail or screw spacing can be increased to 12" o.c., but make sure these fasteners are not neglected. They add stiffness to the wall and prevent a gap from opening up between the panels and frame as the frame shrinks.
6a. Attachment at Bottom of Wall
At the sill, the panels usually rest on a 2x10 or 2x12 pressure-treated sill and are anchored into the band joist as shown in Figure 10. Ardox nails or screws should be used as described above.
|
Figure 10. Panel Attachment at Sill. With typical floor framing, set panels on the sill and nail them into the band joist. This detail may vary depending on the framing system employed. In general, the outer panel surface should be flush with the outside of the finished frost wall (with or without exterior insulation). Make sure you plan this detail out before putting in the foundation.
|
Termites and ants could be a problem with stresskin panels. If termites could be a problem, you should install a termite shield either under the sill as shown in Figure 11 or between the sill and panel. As an additional precaution against insects, you should have the sill and the ground around the foundation wall treated with an insecticide by an authorized exterminator.
If a more traditional timber framing technique is used, with timber sills as shown in Figure 11, panel attachment is somewhat different. The panel is installed on the outside of the timber sill and extends down to the top of the concrete host wall (there may be a pressure-treated 2x10 or 2x12 under the timber sill as shown).
|
Figure 11. Timber Sill Detail. If a timber sill is used, the panel attachment detail at the bottom of the wall will differ. Rest the panel on a pressure-treated sub-sill and secure the bottom edge into the timber sill.
|
After setting a panel in place, carefully check the spacing between it and the adjoining panel. Where spline joints are used to join panels, tap the panels snug against each other for a tight joint. Where the panels will abut on posts, you can leave a ¼" gap and seal the joint later with foam sealant. This technique will produce a tighter and more energy-efficient seal. Make sure panels are plumb.
Secure the panel temporarily with four corner nails tacked in lightly, then wait until the next panel is set in place before tightly setting the nails in the first panel. In this way, any problems you might run into as the next panel is being installed can be remedied. It is particularly important not to tightly set corner nails where splines will be used in joining the adjacent panel. Otherwise, the routed groove will compress somewhat and you may have trouble inserting the splines.
6b. Attachment at Top of Wall
At the top of the wall, panels should be cut at the roof angle so that the roof panels will overlap and rest on them. Leave ¼" between the top edge of the wall panel and the overlapping roof panel to allow filling with foam sealant later. The attachment on side walls will depend on the timber framing system used. With a plate at the top of the wall, as shown in Figure 12, nail or screw the top of the panel to the timber 8" o.c.
Figure 12. Attaching Top of Panel to Plate. The top of the panel should be miter cut even with the roof slope. Cut the panel ¼" short to allow sealing with foam later.
If the timber girt is below the wall-roof intersection and there is no plate at the top of the wall, as is often the case, a separate two-by nailer should be installed at the top of the wall as shown in Figure 13. This both reinforces the connection between wall and roof panels, and hides the drywall joint (which is likely to open up as the timbers shrink). The nailer should be of the same wood as the rest of the frame for aesthetic reasons, and inset into the posts as shown.
Figure 13. Nailer at the Top of the Wall. Use a separate inset nailer if there is no plate at the top of the wall. The nailer reinforces the wall-roof intersection and covers the drywall joint on the interior.
At the gable ends, the wall panels should be cut at the same angle as the top edge of the outside rafters as shown in Figure 14. Again, cut the wall panels ¼" short to leave a gap between the wall and overlapping roof panels. Go back and foam this gap later.
Figure 14. Top of Gable-End Wall Panels. On the gable ends, cut panels at the same angle as the roof. Cut the wall panels ¼" short to provide a gap between wall and roof panels that can be filled with foam later.
Several different outside corner details are shown in Figure 15. The most common corner is a simple overlap, as shown in 15a. The overlapping panel should be routed out 1½" so that a 2x4 can be fully inset for added strength. Remember to rout from the waferboard side to avoid damage to the drywall, as described in Section 5.
Figure 15. Corner Details. Three different options for panel overlaps at corners are shown here. The simple overlap in 15a is the easiest, while the overlap in 15b affords a somewhat tighter seal against moisture and wind, especially until the exterior siding is installed. 15c shows the use of a short panel section to form the overlap. Depending on your framing system, this detail may enable you to use materials more efficiently.
Some builders prefer a somewhat more complex, but tighter, overlapping joint that does not leave a 2x4 exposed. This joint, shown in 15b, is made by cutting out 4½" of the plasterboard and foam, leaving the waferboard extending out to overlap the edge of the other panel.
This detail requires use of a large-diameter circular saw with the depth adjusted so that a cut from the drywall side will be just shy of the waferboard. After making this cut 4½" in from the edge of the panel, the drywall and foam are separated from the waferboard with a handsaw, knife, or the claw of a framing hammer. Any remaining foam can be removed with a paint scraper. The edge of the other panel is routed out from the drywall side to accept a 2x4 nailer as described above, and the panels are attached as shown in the illustration.
Depending on the overall wall dimensions and spacing of posts, it may be desirable sometimes to use corner fillers as shown in 15c. Approximately 2" of the full panel should rest on the corner post allowing a greater purchase area for the narrow filler.
Whichever corner detail is used, panels should be secured to the post as described in Section 6. In options 15a and 15c, you can leave a ¼" gap where the panels overlap and fill it later with foam sealant for a tighter seal.
With inside corners, for example where an "L" extends out from the house, the joint is just the opposite of that shown in 15b. In this case, 4½" of waferboard and foam is removed, leaving the drywall extending out to overlap the adjoining panel as shown in Figure 16. Both panel edges need to be reinforced with 2x4s for added strength because the post does not provide full support. For strength, the panels must be glued together with construction adhesive as shown in the illustration. Use a high-quality construction adhesive, such as "PL 200" or a comparable product. Apply at least two beads of adhesive between the inset spline of one panel and the waferboard edge of the other. This glue, together with the drywall screws or nails through the extended drywall flange, will provide most of the bonding strength for an inside corner.
Figure 16. Inside Corner Details. Inside corners are somewhat more complicated than outside corners because the drywall will be exposed on the interior. The waferboard and foam must be cut out, leaving the drywall extending out to overlap, with inset 2x4s as shown. The panels can be secured to the corner post in several different ways, as illustrated.
For attachment to the inside corner post, three options are possible:
- the post can be somewhat offset so that one panel edge rests on at least 1½" of it (16a)
- the post can be notched for the panel corner to fit in (16b)
- or corner trim boards can be nailed into both the panel and post, supporting and covering up the joint (16c).
With any of these three options, use construction adhesive to help maintain a strong bond between the panels and the post. With options a and b, you may also be able to toenail through the 2x4 spline and into the post. With option c, nails through the corner trim into both the post and panel spline will add strength. With this option, you could also build the corner trim out with structural lumber and facing boards for greater strength.
If there is no post at an inside corner, you should substitute Structurewall panels for Curtainwall panels and build the corner as shown in Figure 16, but without the post. Then apply drywall to the interior panel surfaces and protect the corner with metal corner strips.
Properly framing in doors and windows begins with the panel layout. Full-width panels should abut door openings so that 2x4 splines can run from sill to girt or plate. Use 2x4s here, rather than the dual plywood splines, for added strength. These 2x4s should be inset a full 1½" into the panels as shown in Figure 17. Panel cut-offs can be used to fill in above and below the door openings. To secure these top and bottom sections of panel, glue separate lengths of 2x4s ("cripples") and screw them to the full-height 2x4s. The panel sections are routed 1½", slid into place from the door opening, and secured to these lengths of blocking.
Figure 17. Rough Opening for Door. At rough openings for doors, inset 2x4s should extend all the way from sill to girt or plate, with short panel sections used to fill in above and below the door.
Rough openings cut into panels (e.g., most windows openings) should not be closer than 6" to the panel edge. Leaving less than 6" at the edge of a panel will increase the likelihood of breakage during installation. In situations where less than 6" of panel would be left on either side of the rough window opening, the panel should be ripped at the window edge and a panel joint made there, or the window placement should be changed.
Rough openings for windows should be cut before the panels are installed. Though it is possible to cut openings after the panels are installed, cutting them before is easier and safer because you can work on a horizontal surface. Panels are usually cut with a 16" circular saw with carbide blade (available for sale or rent from Winter Panel Corp.). A handsaw is required for finishing corner cuts. Follow window and door manufacturers guidelines for the rough opening sizes.
Figure 18. Window Openings. When you frame around window openings, have the sill and headers overlap the risers. In routing out the foam around window openings, you will have to remove foam by hand with a chisel or other tool at corners where the router cannot reach.
Once the rough opening for a window is cut, the foam is routed out to a depth of l½" and 2x4s are inset as shown in Figure 18. At corners of rough openings, where the router will not fit, foam may be removed by hand with a chisel or other suitable tool. The sill and header should overlap the ends of the risers so that the risers will support some of the load carried by the header. See Section 18 for details on window and door installation.
Large window openings, such as that shown in Figure 19, can be treated like door openings. Full-width panels should abut each side of the window opening. At the window openings, 2x4 splines should be fully inset (1½"). Above and below the opening, attach short sections of 2x4 (cripples) to the inset splines on either side of the opening as shown in the illustration.
Large panel sections oriented horizontally and routed out 1½" on the ends and the side facing the opening, can then be slid into position from below or above. To use wide sections of panel in this manner, you should be able to nail them into a framing member on the top or bottom (that is, into the girt or plate at the top, or into the band joist or timber sill at the bottom).
Figure 19. Framing Around Large Window Openings. Treat large windows like doors in terms of framing around them. On both sides of the opening, inset 2x4s into panel edges, and scab on short 2x4 cripples into which the filler panels can slide. Use horizontal panel sections above and below the opening to increase strength and eliminate interior taping joints.
There are a number of ways to get panels up on the roof. The preferred (and safest) method is to use a crane. The crane can set panels on the roof quickly and accurately. Do as much prep work as possible (dotting panels, etc.) before the crane arrives to avoid delays when the crane is at your site.
Two different alternatives for picking up panels are shown in Figure 20. A strap can simply be wrapped around the panel. Or a truck tie-down strap with cleats that dig into the foam and hold the waferboard can be used. If panels are to be placed on the roof horizontally, attach the strap near the center of the panel, but slightly offset to one side. If panels are to be installed vertically, offset the strap toward one end of the panel. It is very important to note that with any of these systems, the panel may slip due to improper attachment or unsteady crane operation. Under no circumstances should anyone get underneath a panel being hoisted onto the roof!
Figure 20. Picking Up Panels. There are two recommended options for picking up panels. Wrapping straps all the way around a panel provides the safest option, but the system with a cleat may be somewhat quicker. Whichever method you choose, use great care, and do not stand beneath a panel being lifted!
If a crane is not available, it is possible to pull panels up onto the roof by hand. This can be quite dangerous, however, and the technique is not recommended by Winter Panel Corp. Winter Panel Corp. assumes no liability for injury or damage caused by failure of any type of winch, come-along, block-and-tackle, or strap. Some builders use a ladder winch system such as that shown in Figure 21. One ladder is secured to the opposite side of the roof being closed in, held away from the roof surface with blocking. A ladder winch, rated at 1000#, is attached to the top rung. One or two other ladders are used to extend the roof line down to the ground.
|
Figure 21. Installing Roof Panels Without a Crane. If you don't have access to a crane, panels can be pulled onto the roof by hand using a ladder winch, come-along or block-and-tackle. These techniques can be quite dangerous, however, so use extreme care.
|
Panels are winched up the ladder(s) by a worker on the roof or from another ladder (do not operate the ladder winch while standing on that ladder, because if the cable breaks or the panel slips off, a worker directly behind the winch could be injured), and workers on the roof set them into place. The ladders can easily be repositioned as you move along the roof. The winch should always pull in a straight line. As with the crane installation, never let anyone stand beneath a panel being pulled up onto the roof.
Several different ways of dealing with ridges are shown in Figures 22 and 23. If the roof has a 12:12 pitch, the ridge will form a 90° angle and the peak detail will be very simple – like that on a wall corner (Figure 22a). One panel is cut flush with the roof surface and nailed down as described above. The other panel is cut long enough to overlap. The foam at the outer edge of the overlapping panel is routed out 1½" and a 2x4 is inset. This overlapping panel, reinforced at the outer edge with a 2x4, is then nailed or screwed to the ridge beam.
With pitches other than 12:12, an alternate ridge splice is required. The most common approach with shallow roof pitches is to make an equal miter cut in each panel as shown in Figure 22b. This cut is made with a 16" circular saw set at the appropriate angle. For a tighter joint, the panels can be cut so that they don't quite meet, leaving about a 5° "V" or a ¼" gap, which is later filled with foam sealant.
An alternative with shallow roof pitches is shown in Figure 23a. Set the first panel and, using a 16" circular saw, make a miter cut along its upper edge, even with the roof plane. The other panel is then cut off square so that the top edge (waferboard) will be even with the plane of the roof panel already set. The edge of this overlapping panel is reinforced with an inset 2x4 spline, and a wood filler block is cut to finish off the roof peak. The filler is nailed or screwed in place along the whole peak of the roof. For a tight seal, apply several beads of caulk or foam sealant between the nailer and the intersecting roof panels.
With roof pitches greater than 12:12, the recommended approach is very similar, with a filler block again forming the roof peak (Figure 23b). With steep roofs, you should be extremely careful in handling heavy panels,
Figure 22. Common Ridge Details. The two most common ridge details are shown here. With a 12:12 roof pitch, a simple overlap as shown in 22a can be used. With most other pitches, the panels can be miter cut as shown in 22b.
Figure 23. Sample Ridge Details. Several alternative ridge details, which make use of filler blocks, are shown here. With very steep pitches, details b and c may be the only alternatives to consider, because a miter cut would be too sharp an angle to cut with a 16" circular saw. In option c, the waferboard extends up to the peak providing added protection against rain.
A slightly more difficult alternative with pitches other than 12:12 is to leave the outer skin (waferboard) extending out on the panel with the miter cut (Figure 23c). This requires use of a 16" circular saw set at the roof angle with the depth adjusted so that a cut from the drywall side will not quite reach the waferboard After making this cut, remove the foam and drywall from the waferboard as described earlier, and nail or screw the panels together at the ridge (fasteners should extend through the waferboard and nailer block and into the 2x4 inset into the other panel). With this alternative, somewhat better protection is provided until the roof is shingled.
Panel junctions at roof valleys should rest on V-cut valley rafters as shown in Figure 24. Miter cut both panels to split the valley angle. For steep valleys where the circular saw will not cut all the way through the panel, cut as deeply as possible with the power saw, then finish the cut with a handsaw. As with miter cuts for the roof ridge, a tighter joint can be made by cutting the panels at a slightly wider angle or leaving a ¼" space and filling the gap with foam sealant. The valley should be flashed before applying the roofing.
Figure 24. Valley Details. At roof valleys, panels are joined by making equal miter cuts. For the tightest seal, cut the angles slightly wide or leave a ¼" space and fill the gap with foam sealant.
Openings for roof windows, skylights, vents and chimneys can be precut with the panels on the ground, or cut in place after the roof panels have been installed. Precutting is safer and generally recommended for most openings. For chimney and vent openings, however, if there will be a long wait before the mason or plumber finishes his work, it may be better to wait to cut the openings (also the exact position could change).
Rough openings larger than about 1' on a side should be routed 1½" and fitted with 2x4s as shown in Figure 25. As with window openings, the sill and header 2x4s should overlap the side members.
|
Figure 25. Roof Openings. Rough openings for skylights, roof windows and chimneys are treated like window openings on walls. Frame around them with inset 2x4s. Such openings should generally fall completely within a panel.
|
Openings for chimneys and large roof windows or skylights should be outlined by timber framing as shown in Figure 26. This is required if the roof opening necessitates cutting a purlin or rafter. For chimney penetrations that are not perpendicular to the roof surface, filler blocks may have to be installed at the top and bottom to allow you to bring the roof and ceiling surfaces right up to the chimney. Refer to the building code in your area for the required spacing around a chimney or flue pipe. If there is no code, provide a minimum 1" air space between the chimney and panels.
Figure 26. Framing in Large Roof Openings. Whenever a large roof opening requires cutting a purlin or rafter, the roof framing must be altered to fully support the panels. Be sure to take this into account when designing the frame.
Several different wall-roof intersections at the gable end are shown in Figure 27. In 27a, the roof panel overlaps the wall panel, and the inset 2x4 in the roof panel is flush with the outer surface of the wall panel. In 27b, the roof panel overhangs the wall panel (maximum overhang is 12" for Curtainwall panels and 24" for Structurewall panels). These limits assume that the overhanging panel spans a rafter bay or extends at least 4' back on the roof. For narrow panel sections at the roof edge, the overhang should not exceed the amount of panel that is supported.
Figure 27. Roof Edge at Gable End. The detail you use at gable ends depends, first, on whether you want an overhang and, second, on how to use panels most efficiently. With no overhang, simply overlap the roof panel over the top of the wall panel as shown in 27a. With an overhang, either the full roof panel can overhang the wall panel (27b), or it can end on the outside rafter and filler can be used to provide the overhang.
An alternative overhang arrangement, shown in 27c, is sometimes warranted to optimize the use of roof panels. The roof panel terminates on the end rafter and short panel cut-offs are used to provide the desired overhang. Two inches of the full panel should rest on the rafter, leaving most of the rafter surface for the short section to be securely attached. The overhang should not exceed the width of panel resting on the edge rafter and wall panel. Use a 5/8 x 3" top spline to reinforce the attachment of this panel section. This detail offers the advantage of allowing Structurewall panels to be used for the overhangs, while Curtainwall panels are used on the rest of the roof – where the inside surface is exposed. A stronger overhang will be achieved with a Structurewall panel. With this detail, be sure to fill the foaming channel that will be formed as the top groove is routed.
The roof edge must be reinforced with inset 2x4s and fully protected with trim. The most common details for finishing the gable end roof edge are shown in Figure 28. The simplest detail for a flush overlap is shown in 28a. Two rake boards are nailed onto the 2x4 edge spline as shown. The inner rake board should extend over the intersection between roof and wall panel. To simplify the installation of siding, the inner rake board can be notched or held out with ¾" blocking.
Figure 28. Trim Options at Gable. Several options for trim at the gable end roof edge are shown here. The trim can be as simple or ornate as desired.
With a gable-end overhang, a return must be installed to cover and protect the drywall side of the panel as shown in 28b. More ornate trim details can be built, such as that shown in 28c, to provide whatever architectural style is called for.
Five alternative eave details are shown in Figure 29. With Curtainwall panels, the drywall must be fully protected. A sloped soffit return is shown in 29a. The soffit board (usually a 1x8, 1x10 or 1x12), is miter cut to fit snugly against the wall panel with the other edge cut flush with the end of the roof panel. The frieze board (usually a 1x8) is miter cut to fit against the soffit and notched if desired for wall siding. The fascia boards are cut to fit over the edge of the panel and nailed into the inset 2x4. The drip edge is installed on the top edge.
Figure 29. Eave Details. You have lots of choices with eave details, depending primarily on aesthetic preference.
In 29b, an extended fascia board serves to protect the drywall. The fascia is secured both to the wall panel and to the 2x4 or 2x3 blocking attached to the wall. The blocking should be chamfered to provide a larger area of contact for the fascia.
Figures 29c through 29e show three different straight-return eave details. 29c incorporates more ornate moldings, while 29d is the least ornate and easiest to build. 29e provides a deeper fascia, which may be required to hold a gutter. All three require custom-cut filler blocks with triangular cross sections to secure the fascia and soffit boards.
As can be seen, there are many variations possible with eave details. You should not feel limited to the options presented here. More elaborate eave details can be used to meet period and specialty architecture requirements.
Properly wiring a timber-frame house sheathed with stresskin is not difficult, but it does require using nonstandard techniques. The techniques described below are for exterior walls. Interior partition walls are framed in standard fashion, with stud walls providing the wiring chases. To simplify your wiring, try to make use of interior walls wherever practical. All wiring to upper floors should be run in interior wall cavities or separate chases. Long horizontal runs of wire for the first floor should be run in the basement, with short upward extensions for receptacles and switches.
Consult you local code official about specific requirements, and make sure he understands the system you will be using. The alternatives presented here are only suggestions, and they may not satisfy all local codes. Many code officials are not yet familiar with stresskin panels and the wiring techniques they require, so you may need to spend some time with them to adequately explain the system.
Five wiring alternatives are covered below.
15a. Surface-Mounted Wiring
Surface-mounted wiring is the simplest alternative with stresskin construction. Use special preformed channel (wire mold) that contains the wire and mounts directly on the wall surface as shown in Figure 30. Wire mold is available in metal or plastic from most electrical suppliers. along with all the necessary fittings and elbows for your particular applications.
Surface-mounted wiring has been used for decades in commercial buildings, but only recently has it made its way into houses. Most homeowners have not wanted the wiring to be visible. Surface-mounted wiring is becoming more acceptable, however, particularly with the availability of more attractive wire mold.
A big advantage to surface-mounted wiring is the ease with which modifications can later be made. This will be an important consideration to some homeowners.
Figure 30. Surface-Mounted Wiring. Surface-mounted wire mold is run along the wall near floor level where it will be out of the way and fairly inconspicuous. Long horizontal runs should be carried in the basement, with extensions through the floor for receptacles.
|
Figure 31. Concealed Panel Wiring. With concealed panel wiring, wires are run up from the basement through the foam in the stresskin panel. Use a section of curved ¾" copper pipe to make a hole in the foam insulation for the wire.
|
15b. Concealed Panel Wiring
Concealing electrical wires within Curtainwall panels, as shown in Figure 31, is the most common wiring technique used by timber framers. With horizontal runs of wire in the basement. this is an easy way to install outlet receptacles at the standard height of 16" – 18" above floor level. The steps required are outlined below:
- Cut hole for outlet box in drywall.
-
Dig out foam insulation to required depth for box.
- Mark the floor deck directly below the box and measure from a reference point you can find in the basement.
- From the basement, drill a ¾" - 1" diameter hole through the band joist directly below the outlet box. Angle this hole upward so that it will not penetrate the floor.
-
From above, push a section of curved ¾" pipe downward from the hole made for the outlet box to the drilled hole in the band joist. The pipe gouges a channel through the foam and is then removed The pipe should curve inward so that the channel for the wire will remain close to the inner (drywall) surface. Though this may sound difficult, it is quite easy after some practice.
- Run wire through chase and install receptacle using Madison straps or another suitable type of fastener.
15c. Door Jamb Wiring Chase
After the rough opening for a door is cut and routed out for the supporting 2x4s, wiring may be run upward along the routed panel edge for switches and outdoor lights. A short section of straight pipe is used to make a horizontal chase to the switch on the interior or the light fixture on the exterior. Alternately, the wire itself can be pushed through the foam. When the vertical 2x4 is set into the routed panel edge, it embeds the wire securely and safely into the insulation.
15d. Floor-Edge Wiring Chase
By holding back the flooring and/or subflooring ¾", and using a baseboard made of 5/4 stock, a wiring chase at the perimeter of the floor is created. The baseboard totally conceals the chase. With this technique, wiring can be done after panel installation, and future modifications can easily be made by pulling off a section of baseboard.
The details of this technique will vary depending on the timber framing technique and the flooring/subflooring material. If the posts are set on top of the subfloor and the subfloor was held back ¾" there will be a continuous wiring chase the full length of the wall. If, on the other hand, the posts are set directly on the sill, the posts will have to be routed just below the floor height before panels are installed, or the wire will have to drop down into the basement to get around posts.
This technique is particularly appropriate for upper-floor applications where there is no basement for horizontal wiring runs. With 2" tongue-and-groove pine decking on the second floor held back ¾", a fairly large wiring chase will be created that should be able to hold all necessary wire. On upper floor applications with this technique, posts will usually have to be routed to provide a continuous wiring chase. Rout the posts before installing panels.
|
Figure 32. Door Jamb Wiring Chase. Use this technique for installing light switches and exterior door lights. But make sure you plan for it before you install the panels, so that the wire can be run as the door opening is roughed in.
Figure 33. Floor-Edge Wiring Chase. If wires are run under the baseboard at the floor edge, long horizontal lengths of wire can usually be run quite easily. This technique is a good choice on upper floors (on the first floor, horizontal runs can more easily be carried in the basement).
|
15e. Baseboard Raceway
This technique is becoming the favored wiring alternative by many timber framers using Curtainwall panels. A specially-made baseboard is used, which extends out from the wall at least an extra ¾" to provide a chase for wiring. These baseboards are usually shop-manufactured and cut to length on-site. Receptacles are inset into the baseboard and usually a short distance into the Curtainwall panel as well. Because the receptacles do not penetrate far, if at all, into the insulation, the integrity of the insulation is little affected with this wiring technique. Wires should enter and exit the receptacles through the ends rather than back or sides.
As with the floor-edge wiring chase discussed above, posts will interrupt wiring runs. You will either have to pre-rout the posts from the outside or drop the wire down into the basement to get around the posts.
A slight variation of this technique makes use of surface-mounted, low-profile, baseboard hydronic or electric heating units manufactured in Europe. These baseboard heaters, which stand out little more than a wood baseboard, have a built-in wiring chase. The system is quickly gaining popularity both here and abroad. |
Figure 34. Baseboard Raceway Wiring Chase. With this wiring technique, you use special baseboards that are set out from the wall surface, providing a chase for wires. Modifications to the wiring can easily be made by pulling off sections of baseboard.
|
Because studs are not spaced every 16" or 24" along exterior walls with stresskin-enclosed houses, hanging wall cabinets requires special care. Though a number of techniques have been used, the one that seems to work best is to substitute Structurewall panels for Curtainwall panels in areas where cabinets will be hung on exterior walls (kitchens primarily, but also bathrooms and workrooms in some cases).
With Structurewall panels, the 7/16" waferboard interior skin provides a continuous nail or screw base, so cabinets can be placed wherever they are desired. Their placement is not limited to locations where they can be secured to framing members.
The only difficult part of this technique is installing a continuous interior layer of drywall. (If there are only very small areas on a wall not covered by cabinets, an adequate fire rating can be achieved by simply adding linoleum or almost any other layer – such as a back-splash behind the sink.)
Cabinets can either be installed directly against the Structurewall panels and the drywall fit around them, or a continuous layer of drywall can be applied over the waferboard, and then cabinets installed over that. The first method, with cabinets secured directly to the waferboard, will result in sturdier cabinet attachment, but more difficult drywalling and finishing. With this technique, you can use adhesive as well as screws to attach the cabinets. Screw spacing is unlimited because the waferboard surface is continuous.
To simplify drywall installation and finish work, apply a continuous layer of drywall over the Structurewall panel. There are a number of possibilities for installing drywall. The simplest approach is to put up the wall panels on the exterior of the timber frame in the typical fashion, substituting Structurewall panels for Curtainwall panels where cabinets are to be installed. A section of Structurewall panels should run for an entire bay of the timber frame, or at least up to an interior partition.
Hang drywall right over the structural panels, offsetting the joints by a minimum of 6". Offsetting the joints is very important to prevent drywall joints from opening up. Usually the drywall panels will be hung at right angles to the Structurewall panels as shown in Figure 35. The drywall should be glued and either nailed or screwed to the Structurewall panels at the spacing recommended by the drywall manufacturer. Because there is a continuous nail base under the drywall, any spacing is possible. You should not, however, nail or screw the drywall into the splines connecting panels.
Figure 35. Installing Drywall over Structurewall Panels. Make sure that the drywall and panel edges do not line up. Drywall should be installed perpendicular to the panels or the edges offset by at least 6".
Finishing the drywall (taping, sanding) will be easier if done before cabinets are installed. This will also minimize the risk of scarring or staining the cabinets. At the edges, where the drywall abuts the exposed framing members, cracks will probably open up as the timbers dry and shrink. Corner trim can be used. A specialized product such as Beadex L-Strip™ can be used. Or a final touch-up can be planned for several years down the road. (A better alternative, which does not require specialized trim or resealing cracks, is discussed below.)
Once the drywall is hung, cabinets can be installed by screwing them (through the drywall) into the waferboard of the structural panels. Again, because the waferboard is continuous, any screw spacing can be used.
16a. Preferred Technique for Covering Structurewall Panels
To prevent cracks from opening up at the drywall perimeter, an alternative method can be used as follows: Before installing the Structurewall panels in kitchens or other areas where cabinets are to be attached, rout out the frame ½" or 5/8" along the sides and top of this wall section as shown in Figure 36. The routed channel should be ½" deep for ½" drywall and 5/8" deep for 5/8" drywall. The channels should be about 1" wide.
|
Figure 36. Flexing Drywall Into Routed Channels in Frame. Posts are routed before installing panels so that drywall edges can be slid in. As the timber frame shrinks, large gaps at the drywall edge will not open up. Sheets of drywall are inserted into the routed channels by bowing them.
|
Corner braces, if they are flush with the outside of the posts, must also be routed. A better technique, though, is to set the corner braces in by at least the thickness of the drywall.
Install the Structurewall panels on the outside of the frame, and secure all splines from both the inside and outside. You may then install the drywall sheets horizontally, flexing them to get the ends into the routed grooves, as shown in Figure 36. Insert the upper sheet first and slide it up into the routed groove at the top plate or girt. Screw that into place, then install the lower sheet, cut to fit tightly against the floor or subfloor. Construction adhesive should be used in addition to screws when securing the drywall to the Structurewall panels.
By insetting the drywall into routed channels in the timber frame in this fashion, the exposed framing members can shrink without opening up large cracks at the drywall-timber joint. A cleaner wall is produced, requiring less maintenance. Though it sounds more involved, this wall system can be put up very quickly and easily. Because the drywall is inset into the frame at a depth equal to its thickness, the structural panels against it align perfectly with the other Curtainwall panels used throughout the house. The wall extends ½" or 5/8" further into the house in these areas, but that will not be noticeable if posts or interior partitions separate the wall sections.
16b. Attaching Cabinets Directly to Curtainwall Panels
If Structurewall panels are not used in place of Curtainwall panels to provide a nailing base under the drywall (the recommended technique), cabinets are best installed by securing them to timber framing members. This technique will usually only work if the cabinets extend up to the ceiling or the underside of a spanning girt or plate, as shown in Figure 37. If this is done, make sure the top of the cabinets can carry the weight. Reinforcing the top of the cabinet with corner braces may be required to transfer load to the back and sides.
With a timber girt or plate carrying the weight, cabinets can be held against the drywall surface of the Curtainwall panels with toggle bolts pushed through the drywall into the foam and forced open (toggle bolts cannot support any of the weight of the cabinets; they are only used to hold the cabinets snug against the wall).
Figure 37. Attaching Cabinets to Curtainwall Panels. Depending on the house frame, cabinets may be attached to the underside of a girt or plate. You will probably need to reinforce the tops of the cabinets if using this technique.
Winter Panel Corp. occasionally receives questions about how to correctly install plumbing in timber-frame houses enclosed with stresskin panels. Plumbing details in these houses, however, are no different than those for conventional houses or timber-frame houses with insulated stud walls.
Wherever there is even a remote chance of freezing weather, plumbing should not be installed in exterior walls (this includes most of the United States). This rule stands whether stud walls or stresskin panels are used. The only plumbing that should penetrate the outer shell of a house is the pipe for an outside spigot. Septic ventilation stacks as well as range hood vents, bathroom vents, dryer vents and air-to-air heat exchangers will also penetrate the outer insulated shell of the house, but these do not pose freezing risks.
Plumbing for kitchens and bathrooms is usually run through the floor, hidden by cabinets or enclosed in interior partition walls. Plumbing runs to upper floors are either carried through interior partitions or separate plumbing chases. In timber-frame houses, particularly those with open first-floor layouts, separate plumbing chases are often required. Boxed in with 1x10s or 1x12s, such chases are quite unobtrusive. Hot and cold supply and return lines as well as drainage pipe and septic ventilation can all be carried in these chases. To prevent possible risk of freezing in very cold climates, locate boxed-in plumbing chases adjacent to interior partitions rather than exterior walls.
Follow window manufacturer's instructions when installing windows and doors. Generally, window units will be shimmed from the inside, then nailed from the outside through the trim into the outer skin and 2x4.
Figure 38. Installing Window. Follow window manufacturer's instructions for installing unit into rough opening.
Once secured in place, the window installation is completed by foaming the cavity between window frame and rough opening, as shown in Figure 39. It is important not to fill the cavity all the way, because the expanding foam may make the window difficult to open. Set the foam nozzle ¾" into the cavity and apply a heavy bead of foam that does not totally fill the cavity but continuously "welds" the window unit to the opening. The foam provides extremely good adhesion and will supply most of the holding power. If you find the window is difficult to open after the foam cures, you can make a kerf through the foam with a handsaw to relieve pressure.
Door installation is similar to that of windows. Follow manufacturer's recommendations. Foaming should be done in the same manner as with the windows (see Figure 40).
After installing windows and doors, install trim around the casings in standard fashion. Trim can be nailed into either the window/door casing or the inset 2x4.
Figure 39. Foaming Window on Interior. Once the window has been installed from the exterior, it should be foamed on the interior. Be careful not to apply too much foam, because expansion may make the window difficult to open.
|
Figure 40. Completing Door Installation.
Doors are foamed in the same manner as windows. Follow manufacturer's instructions for installation.
|
Once the house is entirely closed in with panels, any gaps between wall panels must be filled with foam sealant. If ¼" gaps were left between panels at butt joints over framing members, insert the foam nozzle and inject foam into the crack as shown in Figure 41. It may take a bit of practice to completely fill the cavity without having extra foam expand out of the crack. Also inject foam in gaps at the sill and the gap between wall and roof panels. Once the foam has fully cured, cut off any that has expanded out of the gap using a chisel or paint scraper.
Asphalt-impregnated felt is not recommended under wall siding because it prevents breathing, but an air barrier such as Tyvek or rosin paper may be used if desired. Most builders apply the wall siding directly over panels without any paper.
When installing horizontal siding such as clapboards, do not nail directly into the splines or posts because buckling may occur. Do not nail within 6" of the splines or posts, as shown in Figure 42.
Figure 41. Foaming Exterior Gaps. After all panels are installed, seal all gaps between panels with foam sealant. After the sealant has fully cured, cut off any foam that extends out.
Figure 42. Clapboard Siding. Apply clapboards directly over waferboard surface. Do not nail within 6" of splines or posts.
With vertical siding, such as board-and-batten, you can either apply boards directly to the wall panels as shown in Figure 43, or first install strapping to the panels and then boards as shown in Figure 44. This latter approach allows air to circulate behind the siding, reducing cupping and possible rot. If possible, use boards 6" or narrower to prevent cupping. Leave a gap between the boards and screw the battens in place through the gaps. If boards are wider than 8", apply a bead of construction adhesive down the center of the board to prevent cupping. With horizontal siding, you do not need to worry about nailing into splines.
