Curtainwall Q&A No. C-4.2

General

What are the advantages of panels over in-fill walls for timber-frame buildings?
Panels can be installed very quickly. They are very energy efficient and enclose the frame fully, keeping air infiltration to a minimum. They keep the frame fully exposed to view (and protected from possible moisture damage). Drywall finishing is very easy. Shrinkage of the frame over time will not open up cracks in the drywall finish.

What are the disadvantages to panels?
Stresskin panels are still quite new; some builders may not be familiar with installation. Attaching cabinets requires special techniques. There is minimal nailing surface on the inside wall.

Is there an advantage to the 4½" panel thickness?
Yes. Standard doors and windows fit right in, without requiring extension jambs. With the thin wall, you also get more living space for the same exterior dimensions.

How are panels made?
Panels are made in a continuous lamination process in which the foam is injected between the two skins and allowed to expand under carefully controlled conditions.

What skins are used on the panels?
Curtainwall panels have an exterior grade of waferboard/OSB on the exterior and "blueboard" drywall on the interior. The blueboard can be taped and painted like standard drywall, or covered with a skim-coat of plaster for a superior finish.
Winter Panel?s Structurewall™ panels have an exterior grade of waferboard/OSB as both the inner and outer skins.

Why is waferboard used instead of plywood?
The first reason is price ? waferboard/OSB is a lot less expensive. Second, waferboard is available in much longer lengths (up to 28'). Third, waferboard is more stable, particularly in high moisture conditions; delamination and linear expansion are less likely to occur.

What is the R-value of the panel?
The R-value of Curtainwall panels is approximately R-26. The total system R-value is approximately R-28 (this includes the R-value of the panel, air films, and siding or roofing).

Are these "aged" R-values?
Yes, they are conservative values, aged a minimum of twelve months.

Why isn?t there a vapor barrier in the panel?
The panel itself serves as the vapor barrier. Most model building codes require a vapor barrier with a perm rating of 1. The perm rating of our panels is less than 1. Because there are no voids in the panel where moisture can condense, moisture problems are not a concern. Panels will absorb and release some moisture on a seasonal basis, just as the wood in a log home does, but there are no harmful sects of this cycling.

Do I need to add a vapor barrier or use a vapor-retardant paint?
No vapor barrier is required with the panel. The only place where moisture migration could conceivably be a concern is at panel joints. For this reason, a bead of foam sealant is applied in pre-routed foaming channels between panels during installation.

Do I need to allow an air space for ventilation on the roof if I?m using panels?
No. Ventilation is only required for roofs where moisture could condense in the roof system, or where high temperatures could damage the insulation. Neither of these is a concern with our panels. The only exception is if you are installing a rigid shingle roof, such as wood shakes, tile or slate, in which case horizontal strapping should be used.

Are there any problems with dimensional stability of panels?
Panels are quite stable, but will expand somewhat under high moisture and temperature conditions. At 160°F and 100% relative humidity, panels will expand 5% over 24 hours. Lowering the temperature to -20°F will result in a .15% volume decrease over 24 hours.

Do the panels carry a guarantee?
Yes, Winter Panel Curtainwall and Structurewall panels come with a full ten-year warranty, covering defects in materials and workmanship. For complete warranty information, contact the company.

ENVIRONMENTAL AND HEALTH CONCERNS

What kind of foam is used in the panel?
Polyisocyanurate, an advanced formulation of urethane, developed for high R-value and fire safety.

Is there any outgassing from the foam? What kind of gas is it and do I need to worry about it?
Freon is used as the blowing agent for the foam. A very small amount of Freon will outgas from the foam over time, but the gas is considered completely harmless. It has been used as a refrigerant for many years, with no detrimental health sects.

Is there any formaldehyde in the foam?
No.

What about formaldehyde outgassing from the waferboard?
Exterior grade waferboard, such as that used by Winter Panel, is made with phenol-based resins that do not release significant amounts of formaldehyde gas. Urea formaldehyde resins, which are used in interior grade particle board products, release far more formaldehyde gas, and it is these products ? not waferboard ? that have heightened concerns over formaldehyde in houses.

What happens when the panels burn?
When the panels burn, a number of gasses are given off. Some of these are dangerous, including carbon monoxide and certain hydrocarbons. The exact composition of the combustion products depends on the fire conditions (how much oxygen is available, etc.). You should assume that the gasses given or by all stresskin panels are dangerous. The toxicity of gasses given off from our panels during combustion is about the same as that from white oak or Douglas fir.
A key advantage of urethane foam is that the foam does not melt. Urethane is a "thermo-set" plastic and will retain its structural integrity until consumed by fire (like wood). Other types of foam melt with temperatures as low as 170慚, and can contribute tremendous quantities of fuel to a fire very rapidly. Additional information on fire safety of panels is available from Winter Panel Corp.

What is the wall finish fire rating for Curtainwall panels?
ASTM testing by an independent laboratory showed the wall finish rating of Winter Panel's Curtainwall panels to be 22.5 minutes. Complete information on wall and roof finish ratings is available from Winter Panel Corp.

What are the building code requirements for panels relative to fire?
Building and fire codes vary from place to place. Usually, a 15-minute finish rating is required for light construction. Curtainwall panels exceed this requirement substantially.

Do I need an air-to-air heat exchanger?
Air-to-air heat exchangers or other types of mechanical ventilation are recommended in all tight houses, including those enclosed by stresskin panels. Winter Panel Corp. recommends that air-to-air heat exchangers be incorporated into all stresskin-clad houses.

INSTALLATION

Can panels be installed on any timber frame building, old or new?
Yes.

Does my timber frame need to be specially designed or built to be enclosed with panels?
There are few strict rules; panels can be installed on almost any timber frame. Panel installation can be simplified, however, by following certain guidelines when designing and building the frame. Build the frame on a 4' module, especially the roof framing. Try to make sure all roof panels will be supported on all four edges ? this will simplify installation and interior finishing. Allow for overhangs at the roof edges when spacing the timber purlins and/or rafters.
Winter Panel Corp. can provide you with detailed information on frame design to optimize the use of stresskin panels.

Should roof panels be installed parallel with the roof ridge or perpendicular to the ridge?
That depends on the framing system employed. With timber rafters 4' on center, panels are usually applied perpendicular to the ridge. If major rafters and purlins 4'o.c. are used, panels should be run parallel with the ridge.

How should wall panels be installed?
Wall panels are generally installed vertically, secured to the sill at the ho(tom and girt or plate at the top. Depending on the wall dimensions and window/door placement, however, it may make sense to install some panels horizontally. Contact Winter Panel Corp. for complete installation information.

How far will a Curtainwall panel span on a roof or wall?
Roof panels should not span more than 4' (the width of the panel). As long as both edges are supported by rafters or purlins, the span in the other dimension can be up to 16' (the longest pane! available). If wall panels are secured to the frame at top and bottom, the allowable unsupported vertical span varies, depending on design wind loads and the spacing of vertical posts to which panels are also secured, but vertical spans over 10' are usually acceptable. Contact Winter Panel Corp. for engineering specifications.

How much overhang is allowed with panels?
Full-width Curtainwall panels may overhang the timber frame up to 12". Structurewall panels may overhang up to 24". With narrow panel sections at the roof edge, the overhang should not exceed the amount of panel supported on the rafter and top edge of wall panel.

How many days does it take to panel a house?
A typical timber-frame house can be fully enclosed with panels in 4-8 days, depending on the size of the house, its design, and the experience level of the panel installers.

Who installs the panels?
Winter Panel Corporation can recommend an experienced crew to install your panels, you can install them yourself, or you can hire your own contractors.

How difficult is it to install panels?
Panel installation is not difficult, but it is very different from conventional construction and requires some specialized knowledge. Winter Panel Corp. publishes the Timber Framer's Guide to Stresskin Panel Installation, which will provide all the information you need. Winter Panel can also provide instruction on panel installation.

Where can I get specialized tools required for cutting and routing panels?
Winter Panel Corp. offers for sale or rent large-diameter circular saws and routers with custom-made bits for routing foam. If you are only doing one installation, it probably makes sense to rent rather than buy the required tools.

How do I get panels up on the roof or on second-floor walls?
A crane is the best option for quickly setting roof panels and upper-story wall panels. If you do not have access to a crane, it is possible to install panels by hand, using a ladder winch or come-along to pull them up ladders leaning against the roof.

What kind of nails should be used for panel installation?
We recommend a hot-dipped galvanized annular or ardox nail. Use 6" nails for hardwood frames, and 7" or 8" nails for softwood frames. You can also use 6" hardened steel galvanized screws.

What nail spacing is required for securing panels to the frame?
Panels should be nailed to a framing member 8" on center on two parallel sides of the panel.

How are panels connected together in a wall?
Panels are usually connected with dual 5/8 x 3" plywood splines. The splines are inset 1½" into pre-routed grooves in each adjoining panel. The inner and outer skins of each panel are nailed or screwed into the spline. To secure the waferboard to the spline, use 6d or 8d galvanized nails or l¼" to 1½" galvanized drywall screws. To secure the drywall to the spline on the inside, use either 1¼" to 1½" drywall screws or ring-shank drywall nails (galvanized preferably). These fasteners should be spaced 8" on center.
As panels are installed, foam sealant is applied in pre-routed foaming channels between the splines. This assures a tight seal between panels.

Where do I get the splines?
Winter Panel Corp. sells pre-cut splines in 8' lengths.

Do these splines work for all panel joints?
Dual 5/8 x 3" splines work for most unsupported panel joints. With very long spans, however, stronger splines may be required. If the unsupported wallspan is over 9', Winter Panel Corp. recommends that a 2x4 spline (inset ¾" into each adjoining panel) be used rather than the dual 5/8 x 3" splines. Contact Winter Panel for more specific information on the use of 2x4 splines.

How do I rout the panels?
Winter Panel Corp. can provide either pre-routed or square-edge panels so, by carefully planning your design, you won't have to rout many panels. For routing the grooves, use specially-made router heads, available from Winter Panel Corp.

Do all panel joints need to be reinforced with splines?
No. Panel joints which meet over framing members (posts, rafters, purlins) do not need to be splined. These joints should be sealed with foam sealant, and both panel edges nailed or screwed into the framing member.

How are window and door openings made?
The rough openings are cut right into the panels, preferably before the panels are set in place. Then the foam is routed our the full width of the panel (1½" deep) around the whole perimeter of each opening, and 2x4s are installed for reinforcement.

What happens if it rains while panels are being installed?
Curtainwall panels should be kept wrapped until use. Special care should be taken to rewrap bundles which have been opened if rain threatens. If panels become wet, the paper on the drywall may mildew and swelling of both drywall and waferboard edges may occur to some extent. If panels are moved while wet, the paper on the drywall may peel up.

Is exterior siding applied directly to the panel skin?
Usually. Felt paper and other moisture barriers are not required between the panels and siding. An air barrier such as Tyvek™ or Typal may be used, but is not required. In some situations, wood strapping should be attached to the wall first, then the siding secured to the strapping.

How should siding be applied?
Horizontal siding such as clapboards should not be nailed directly into splines or timbers to avoid rippling of the siding. Keep nails at least 6" from splines and posts. With vertical board-and-batten siding and shingles, you may nail into splines without worry. Use galvanized 6d nails for clapboards and 6d nails for board-and-batten. If using wide boards in board-and-batten siding, the use of strapping will reduce cupping.

How should roofing be applied?
Installation of the roofing should be completed as quickly as possible to reduce the possibility of water damage.
First make sure panel joints are smooth. If moisture has caused swelling, or if a panel for some reason doesn't align exactly, sand down the waferboard to make the joint even. Seal any gaps with foam sealant. Then apply tar to the joint. The entire roof surface should be totally waterproof even before applying the roofing.
Roofing felt is required with stresskin roofs. Follow manufacturer's instructions for installing shingles. With wood shakes, apply a layer of roofing felt first, then install horizontal strapping so that air can circulate behind the shakes and increase their life. Use standard galvanized roofing nails.

How should drywall joints be finished on the interior?
Drywall joints can be taped and finished in standard manner with paper tape and drywall compound, or you can tape the joints and then apply a skim-coat of plaster over the entire walls. Skim-coated drywall is quickly gaining popularity because it generally produces a better, longer-lasting wall and ceiling finish. For skim-coating, a prep coat usually must be applied to the blueboard before plastering. Follow plaster manufacturer's recommendations. If you are finishing just the joints, a dry-mix compound such as Durabond 90 or equivalent is recommended.
If you planned for stresskin panels when designing the frame, many of the panel joints with probably be hidden behind posts, girts, plates, rafters or purlins, minimizing the amount of finishing work required.

How do you run wiring in panels?
There are a number of options for running electrical wiring in houses enclosed with stresskin panels. Wires can be run on the surface of the panels in closed wire mold or in extended baseboards. Another option is to keep most of the horizontal wiring runs in the cellar, with extensions up through the panels for outlet boxes, switches and wall lights. In this case, push wires down through the foam into the floor framing for the house. Finally, wiring can be run along the floor edge by holding the subfloor and finish flooring back 3/4" and using 5/4 stock for baseboards.
Winter Panel Corp. has a wiring detail sheet which describes these options in greater detail.

How are electrical boxes attached to panels?
The boxes are usually cut into the wall and secured with Madison straps.

How do you run plumbing in panels?
Normally, you would never run plumbing in exterior walls. Keep all plumbing runs in interior partition walls, which are framed in conventional fashion), or in separate plumbing chases.

How do you hang pictures on a panel wall?
Light pictures can be hung from hangers nailed just into the drywall surface of the panel. For heavier pictures, nail hangers into splines or attach to the wall with toggle bolts pushed into the panel and expanded behind the drywall. Another alternative is to hang pictures from vertical wires extending down from exposed timber girts or plates.

How are kitchen cabinets hung from Curtainwall panels?
There are several ways to hang kitchen cabinets. The best option is to substitute Structurewall panels for Curtainwall panels in locations where cabinets are to be hung. In this case, you will need to install drywall over them (at least over areas of the wall which will not be covered by cabinets) to provide a 15-minute finish rating required by code. If you are drywall ling the whole wall, your job will be simplified if you first rout the timber frame out by the thickness of the drywall to a depth of an inch or so at all drywall edges. In this way, drywall can be bowed slightly and set in place against the Structurewall panels, without risk of cracks opening up as the timbers shrink. Cabinets can be screwed through the drywall and into the waferboard of the Structurewall panel.
Another option, using just Curtainwall panels, is to hang cabinets from an exposed timber girt. In this case, the cabinets may need to be reinforced inside so that the tops can carry the full weight. Glue and/or toggle-bolt the cabinets to the wall as well.

FOR MORE INFORMATION
For additional information on Winter Panel stresskin products and installation information, visit our form or contact the company.

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