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Mobile ViewAIR CONDITIONING & HEAT PUMP SYSTEMS ENERGY SAVINGS in buildings ICE DAM PREVENTION INSULATION IDENTIFICATION GUIDE INSULATION INSPECTION & IMPROVEMENT AIR BYPASS LEAKS AIR CHANGE RATE ACH HEAT SAVINGS AIR FILTERS for HVAC SYSTEMS AIR LEAK DETECTION TOOLS AIR LEAK MINIMIZATION AIR LEAK SEALING PROCEDURE AIR SEALING STRATEGIES ANIMAL ALLERGENS APPLIANCE EFFICIENCY RATINGS ASBESTOS FLOORING HAZARD REDUCTION ASBESTOS-FREE INSULATION MATERIALS ASBESTOS IDENTIFICATION IN buildings ATTIC LEAKS, CONDENSATION & MOLD ATTIC VENTILATION BACKDRAFTING HEATING EQUIPMENT BASEMENT CEILING VAPOR BARRIER BASEMENT HEAT LOSS BASEMENT LEAKS, INSPECT FOR BASEMENT WATERPROOFING BATH & KITCHEN DESIGN GUIDE BATHROOM VENTILATION BIOGAS PRODUCTION & USE BLOWER DOORS & AIR INFILTRATION BLOWER FAN CONTINUOUS OPERATION BLOWER FAN OPERATION & TESTING BLOWN-IN INSULATION BRICK LINED WALLS BRICK VENEER WALL INSULATION BRICK VENEER WALL Loose, Bulged BRICK WALL DRAINAGE WEEP HOLES BUCKLED FOUNDATIONS due to INSULATION? BUILDING NOISE DIAGNOSIS & CURE CATHEDRAL CEILING INSULATION CATHEDRAL CEILING VENTILATION CEILING FINISHES INTERIOR CEILINGS, DROP or SUSPENDED PANEL CEILINGS, PLASTER TYPES CHIMNEY INSPECTION DIAGNOSIS & REPAIR COOLING LOAD REDUCTION by ROOF VENTS COMBUSTION AIR for TIGHT BUILDINGS CONDENSING BOILERS/FURNACES DAMAGE CONDENSATION or SWEATING PIPES, TANKS COOLING LOAD REDUCTION by ROOF VENTS CRAWL SPACES DEFINITION of Heating & Cooling Terms DEHUMIDIFICATION PROBLEMS DEW POINT CALCULATION for WALLS DEW POINT TABLE - CONDENSATION POINT GUIDE DUCT SYSTEM & DUCT DEFECTS REMOTE ELECTRIC POWER, PHOTOVOLTAIC ELECTRIC HEAT ELECTRIC POWER, PHOTOVOLTAIC, REMOTE SITE ENERGY SAVINGS in buildings ENERGY STAR PROGRAM EVAPORATIVE COOLING SYSTEMS FIBERGLASS INSULATION FIBERGLASS HAZARDS FIBERGLASS INSULATION MOLD FLASHING MEMBRANES PEEL & STICK FLAT ROOF MOISTURE & CONDENSATION FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP FLOODS IN buildings-mold FLOOR COVERING for OVER THERMAL MASS SLABS FLOOR TYPES & DEFECTS FLOOR TILE HISTORY & INGREDIENTS FOUNDATION WATERPROOFING FRENCH DRAINS FRAMING DETAILS for BETTER INSULATION FRAMING DETAILS for DOUBLE WALL HOUSES FRAMING METAL STUD PERFORMANCE FREEZE-PROOF A BUILDING FROST HEAVES, FOUNDATION, SLAB GREEN BUILDING CONSTRUCTION CODES GUIDES GREENHOUSE DESIGN for SOLAR HEATING HEAT LOSS in buildings HEAT LOSS DETECTION TOOLS HEAT LOSS INDICATORS HEAT LOSS PREVENTION PRIORITIES HEAT LOSS R U & K VALUE CALCULATION HEAT LOSS RATE CALCULATIONS HEAT TAPES & CABLES on Roofs for Ice Dams HEATING COST SAVINGS METHODS HOT ROOF DESIGNS: Un-Vented Roof Solutions HOUSEWRAP AIR & VAPOR BARRIERS HOUSE DOCTOR, how-to be HUMIDITY LEVEL TARGET ICE DAM PREVENTION INDOOR AIR QUALITY & HOUSE TIGHTNESS INDOOR AIR QUALITY IMPROVEMENT GUIDE INSULATION CHOICES Insulation Air & Heat Leaks INSULATION FACT SHEET- DOE INSULATION for GREENHOUSE or SOLARIUM INSULATION IDENTIFICATION GUIDE INSULATION INSPECTION & IMPROVEMENT INSULATION R-Values & Properties Air Bypass Leaks, Thermal Tracking AIR LEAK DETECTION TOOLS AIR LEAK MINIMIZATION AIR SEAL STRATEGIES ATTIC CONDENSATION CAUSE & CURE BASEMENT CEILING VAPOR BARRIER BASEMENT De-Watering Systems BASEMENT HEAT LOSS Blocked Soffit Intake Vents BLOWER DOORS & AIR INFILTRATION BLOWN-IN INSULATION BRICK or BLOCK WALL CAVITY INSULATION BRICK VENEER WALL INSULATION CATHEDRAL CEILING INSULATION CATHEDRAL CEILING VENTILATION HOT ROOF DESIGNS: Un-Vented Roof Solutions ENERGY SAVINGS in buildings ENERGY SAVINGS RETROFIT CASE STUDY ENERGY SAVINGS RETROFIT LEAK SEALING GUIDE ENERGY SAVINGS RETROFIT OPTIONS ENERGY STAR PROGRAM ENERGY USE MONITORING FIBERGLASS DUCT, RIGID CONSTRUCTION FIRE PROTECTION FOR FOAM BOARD INSULATION FOUNDATION INSULATION OPTIONS FRAMING DETAILS for BETTER INSULATION FRAMING DETAILS for DOUBLE WALL HOUSES FRAMING METAL STUD PERFORMANCE HEATING COST SAVINGS METHODS HIGH MASS TRADEOFFS, HEATING vs COOLING HOUSE DOCTOR, how-to be Inspect Attics for Moisture or Mold Inspect Attics for Blocked Soffit Intake Vents Inspect Basements for Moisture or Mold Inspect Building Exterior - Roof Venting Inspect the Ridge Vent System from the Attic Inspect the Soffit Vent System from the Attic Insects & Foam Insulation Insulation Air & Heat Leaks INSULATION for GREENHOUSE or SOLARIUM INSULATION CHOICES INSULATION FACT SHEET- DOE INSULATION PLACEMENT in buildings INSULATION R-Values & Properties LOG HOME ENERGY EFFICIENCY LOG HOME WALL INSULATION VALUES PHENOLIC FOAM INSULATION POLYCARBONATE GLAZING POLYISOCYANURATE FOAM INSULATION POLYISOCYANURATE FOAM BELOW SLABS POLYSTYRENE FOAM INSULATION RADIANT BARRIERS REFLECTIVE INSULATION RIGID FOAM USE INDOORS ROOF VENTING ENERGY SAVING DETAILS ROOF VENTING NEEDED? ROOF VENTILATION SPECIFICATIONS REMOTE ELECTRIC POWER, PHOTOVOLTAIC ROCK-BED SOLAR HEAT STORAGE DESIGN SLAB INSULATION, PASSIVE SOLAR SLATE THERMAL MASS for SOLAR HEAT STORAGE SOUND CONTROL in buildings STRESS SKIN INSULATED PANELS STUCCO OVER FOAM INSULATION SUPER HI-R INSULATION SUPERINSULATION RETROFIT Urea Formaldehyde Foam Insulation UFFI URETHANE FOAM Deterioration, Outgassing VAPOR BARRIERS & AIR SEALING at BAND JOISTS VAPOR BARRIERS & CONDENSATION in buildings VAPOR BARRIERS & HOUSEWRAP VAPOR CONDENSATION & BUILDING SHEATHING VERMICULITE INSULATION INSULATION LOCATION - WHERE TO PUT IT INSULATION MOLD INSULATION R-Values & Properties LEED GREEN BUILDING CERTIFICATION LEED Building Designation & IAQ LIGHTING, EXTERIOR GUIDE LIGHTING, INTERIOR GUIDE LOG HOME ENERGY EFFICIENCY LOG HOME GUIDE LOG HOME WALL INSULATION VALUES METHANE GAS SOURCES MOBILE HOME INSPECTIONS MOISTURE CONTROL in BUILDINGS MOLD in FOAM INSULATION, RESISTANCE MOLD INFORMATION CENTER Nanomaterials Hazards NOISE / SOUND DIAGNOSIS & CURE NOISE CONTROL for HEATING SYSTEMS NOISE CONTROL for FLOORS NOISE CONTROL for PLUMBING NOISE CONTROL for ROOFS ODORS & SMELLS DIAGNOSIS & CURE PAINT FALURE, DIAGNOSIS, CURE, PREVENTION PASSIVE SOLAR DESIGN METHOD PASSIVE SOLAR HEAT PERFORMANCE PASSIVE SOLAR HOME, LOW COST PHOTOVOLTAIC POWER SYSTEMS PLASTER & BEAVERBOARD & DRYWALL PASCAL CALCULATIONS RADIANT BARRIERS RADIANT HEAT RADIANT HEAT Floor Mistakes to Avoid RADIANT HEAT TEMPERATURES RADIANT SLAB FLOORING CHOICES RADIANT SLAB TUBING & FLUID CHOICES ROOFING INSPECTION & REPAIR ROOF VENTILATION SPECIFICATIONS ROT, FUNGUS, TERMITES ROT, TIMBER FRAME SEARS KIT HOUSES SHEATHING, FOIL FACED - VENTS SOLAR ENERGY SYSTEMS SOUND CONTROL in buildings STAIN & BIODETERIORATION AGENT CATALOG STAINS on buildings - QUICK GUIDE STAIN DIAGNOSIS on BUILDING EXTERIORS STAIN DIAGNOSIS on BUILDING INTERIORS STAINS on INDOOR SURFACES: PHOTO GUIDE STAIRS, RAILINGS, LANDINGS, RAMPS STONE CLEANING METHODS STRUCTURAL INSPECTIONS & DEFECTS STRAW BALE CONSTRUCTION STRESS SKIN INSULATED PANELS STUCCO WAll FAILURES DUE TO WEATHER STUCCO WALL METHODS & INSTALLATION STUCCO OVER FOAM INSULATION STUCCO PAINT FAILURES STRUCTURAL INSPECTIONS & DEFECTS SUMP PUMPS GUIDE SWEATING (CONDENSATION) on PIPES, TANKS THERMAL EXPANSION of MATERIALS THERMAL MASS in buildings THERMAL TRACKING Indicates Heat Loss VAPOR BARRIERS & AIR SEALING at BAND JOISTS VAPOR BARRIERS & CONDENSATION in buildings VAPOR BARRIERS & HOUSEWRAP VAPOR CONDENSATION & BUILDING SHEATHING VENTILATION in buildingS WALL FINISHES INTERIOR WATER ENTRY in buildings WIND ENERGY SYSTEMS WIND TURBINES & LIGHTNING WIND WASHING INSULATION At EAVES WINDOWS & DOORS WINTERIZE A BUILDING WOOD, COAL STOVES & FIREPLACES WOOD STOVE SAFETY ZONE VALVES More Information |
Building with stress-skin panels: this article discusses the use of stress skin insulated structural panels for timber frame and other construction. InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers nor with topics or services discussed at this website.Illustration at page top and accompanying text are reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss. © Copyright 2012 InspectAPedia.com, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use page top links to major topics or use links at the left of each page to navigate within topics and documents at this website. Green links show where you are in a document series or at this website. Stress Skin Panel ConstructionThe text below paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss. Stress Skin Structural Panels
Home buyers and regulators demand greater energy efficiency in new homes. This was true in 1964 when the U.S. FPS studied the durability of stressed skin panels, it was still true in the 1980's when we looked at the use of stress-skin panels in Solar Age Magazine [September 1986] and it remains true today, more than eighty years since the US FPL began studying SIPs. Photo (above-left) U.S. Forest Products Laboratory Structural Insulated Panel based prefab houses developed in 1937, built for study and evaluation. Stress-skin panels are used to wrap around structural timber frames, to sheathe the roofs of cathedral ceilings, and even to build the entire building shell. All of the stress-skin panels for residential construction use similar components. They have polystyrene or polyurethane foam cores and are faced on either side with a "skin" - generally plywood, composition board, OSB, or drywall. But standardization ends there. Beyond the basic material options, stress skin panel products take off in a variety of directions that affect cost, performance, and durability. Definition of SIPs, Structural Insulated Panels or Stress-Skin PanelsWhat is an SIP or stressed skin panel or structural insulated panel?
Rivalry Among Styrene & Urethane Stress Skin Panel Manufacturers
The vast majority of the stress-skin insulated panels use polystyrene - commonly called beadboard - for the simple reason that it is much cheaper than urethane foam. William Porter of W.H. Porter Company, Holland MI, a producer of both types of panels indicated that in the 1980's beadboard-filled stress skin insulated panels were selling 10 to one over urethane foam based panels. Those who want the urethane, said Porter, are looking for higher R-values, "... but don't want to go to a foot-thick stress-skin panel." Our photo (above, left) from the original Solar Age stress skin panel article illustrates wrapping the house with stress-skin panels with drywall on the interior and OSB on the exterior. If heavy siding is used or the exterior is shingled, the OSB has to be strapped. [Click any image for an enlarged, detailed view.] Inch for inch, a urethane foam core stress skin panel may cost twice as much as a beadboard panel. But compared by R-value the differences are small, said Amos Winter of the urethane-panel manufacturing firm Winter Panel Corp. in Brattleboro, Vermont. An average 5 1/2-inch foam core stress skin panel filled with beadboard cost [1980's prices] from $1.75 to $2.20 per square foot, said Winter, compared with $2.20 for a 3 1/2-inch urethane stress skin foam core panel with comparable R-value. Urethane foam offers R-6 to R-7 per inch (according to most sources) compared with beadboard's R-3.8 per inch. How well either product holds its R-value over time is another bone of contention. [See INSULATION R-Values & Properties and POLYSTYRENE FOAM INSULATION and URETHANE FOAM Deterioration, Outgassing for current details.] Fire Safety of Types of Stress Skin Insulated Structural Panels
The problem, says Amos Winter, "... is that beadboard panels will fail structurally when the foam starts to melt at around 200 degF, whether the panels burn or not." He says that the melted styrene (it flows at around 250 degF) will feed a fire like molten wax from a candle. Urethane foam burns more like wood, he says. It stays intact until it burns through. Winter believes that a styrene foam insulated panel system is more acceptable if it has fire-stops throughout and full structural supports - for example, a system with full 2-by splines at all panel joints and edges. Our photo (above, left) from the original Solar Age stress skin panel article illustrates the installer improving the thermal performance of the stress skin panels by filling joints with one-part urethane foam. Either type of insulated foam panel can be made to comply with the 15-minute thermal-barrier requirement. But the codes were not written [prior to 1986] "... for a system that melts." says Winter. William Porter, who makes both beadboard and urethane foam core stress skin panels, points out that both will burn at higher temperatures. He feels that the code requirement for 1/2-inch drywall on studs and 1/2-inch wood on ceiling panels is adequate. Using just drywall on a ceiling stress-skin panel is unwise, anyway, says Porter, because the panel could sag if the drywall ever got wet. Styrene stress-skin foam core panel supporters counter by arguing that melting temperatures [of the foam insulating core] don't occur in walls or roofs under normal conditions or even during small fires. One manufacturer, Enercept in Watertown SD, says that its panel with drywall and waferboard on the interior surface passed the UL "corner test" intact. In that Underwriters Laboratories fire test, a 35-pound wood pile is ignited in a full-scale mock-up building corner. This type of test is challenged by Winter. He says it isn't representative of condition in a real fire because the space is not enclosed. Longevity / Durability of Stress-Skin Insulated Foam Core Panels
In a batch of urethane panels produced early on in the 1980's, the foam shrunk and warped the panels, said Winter, who removed and replaced them. The foam core panel shrinkage problem was solved, he says, by improving the chemistry of the foam insulation. The message is clear: Urethane foam "needs a good cook" to insure good performance. Our photo (above, left) from the original Solar Age stress skin panel article shows an employee of Atlas Industries, Ayer MA, preparing stress skin foam insulated panels by routing out space to allow spline inserts where panel edges meet. The company has produced stress skin insulated foam core building panels since the mid 1970's. More important to the durability of stress skin panels is the longevity of the foam core itself and the bond of the foam insulating core to the facing materials of the panel. Many distrust the life expectancy of 1-pound density styrene beadboard, which has a soft, breakable consistency. To get a good bond, the adhesive must penetrate into the beadboard, says Winter. He prefers urethane adhesive with beadboard cores. Urethane, on the other hand, is difficult to bond to because the cells on the surface are cut open "like cracked egg shells". US FPL study on the durability of stressed skin panels or SIPsSee Stressed Skin Panel Performance After Twenty-Five Years of Service. Quoting from that document's summary, and recognizing that panels, foam insulation, and adhesives have surely improved since the orignial 1962 study:
Stress Skin Panel Facings & Bonding
Our photo (left) from the original Solar Age article shows stress skin panels and timber frame components for a completely pre-cut kit house using polystyrene panels and a simplified timber frame system sold by Northern Energy Homes. "Laminating [foam core insulated building panels] is tricky", says Porter. "If you haven't made a mistake you haven't been in the business long." At one point, he says, his company used an adhesive with a plasticizer that dried up over time and eroded the bond to the stress skin panel. Most glues are sensitive to air temperature and moisture content. They require industrial-type clamping to get good performance. If laminating is difficult, foaming stress skin panels in place is even more so, says Winter, a veteran urethane foamer. The process is technically complex, chemically volatile, and as much art as science. Do-it-yourself Home Made Stress Skin Insulated Foam Core Building Panels?The manufacturers do seem to agree that it's best to avoid home-grown stress-skin insulated building panels - particularly if the panels will bear structural loads. The bond of foam to facing is what transfers the loads to the panel skin and gives the panels their strength. Stress Skin Insulated Building Panel Construction DetailsBest Skin Material for Stress Skin PanelsAs for the best skin material for stress-skin foam core panels, there is little agreement. Timber-framer Benson experimented with plywood on the exterior. He says he had problems with the plies delaminating. By the early 1980's he had switched from waferboard panels to Oriented Strand Board (OSB) because it is stronger and holds nails better than the waferboard. Stress Skin Panel Strapping for SidingAll panel facing materials have to be strapped, he says, to receive heavy sidings, because there are no studs. Another timber-framing company, Northern Energy Homes [photo above] tried waferboard panels before switching back to plywood skinned panels. The waferboard had a "negative appeal to clients" and the savings in cost over plywood were marginal. Interior Facings for Stress Skin Foam Core PanelsOn the interior face, Northern Energy Homes uses either 3/4-inch T&G Pine or 1/2-inch drywall. The 1/2-inch drywall is backed by 1/4-inch waferboard - there to keep the panels a uniform thickness and to provide a nailbase for interior trim. With just a drywall skin, hanging finish materials such as kitchen cabinets can present a problem. Tedd Benson has 2x4's custom fitted into the kitchen stress-skin wall panels where wall and base cabinets will attach. For lightweight items, he says, molly bolts into the foam work just fine. Joints, Grooves & Slots in Stress Skin Building Panels
Our photo (left) from the original Solar Age article illustrates a bowed-roof cape design using structural panels on a home from Winter Panel Corp. How finicky one must be at the stress skin panel joint is a matter of judgment. A full wood spline - for example, a 2x6 for a nominal 6-inch foam core panel - is the most common treatment at a joint. A full spline nailed through from both faces, and sometimes glued, provides good structural continuity. But the stress-skin panel joint is a weak link thermally. This will often result in "melt lines" or "frost lines" showing on the roof. Full splines can also lead to cracked drywall joints on the building interior if the wood spline swells during the first winter. To beef up the stress skin panel joint thermally, many have switched to a double-spline system. This improvement is still vulnerable to thermal, air, and moisture leaks. To bridge the gap thermally, Benson intentionally leaves a 3/8-inch gap in the foam between the splines. The gap is foamed through 1/4-inch holes drilled about every 10 inches from the outside. Northern Energy Homes uses a 1 1/2 x 2-inch foam spline to get thermal continuity. Its panels are slightly beveled, leaving a gap on the outside to be foamed for an airseal. Special Considerations for Stress-Skin Insulated Panel RoofsStress-skin roofs face another nuisance. Sometimes roof shingles refuse to lie flat over the stress-skin panel joints. The cause is attributed to expansion of the waferboard, which buckles the shingles. This problem has also been reported on conventional roofs with waferboard roof sheathing. One solution, reports Winter, is to seal the waferboard edges with roofing cement and then wet down the roof to "condition" it to its normal moisture content. Some waferboard manufacturers are said to be responding to the problem by preconditioning their panels. Tedd Benson says that his solid foam-to-foam joint seems to prevent this problem, which he blames in part on moisture that escapes and condenses under the shingles. Stress-Skin Foam Core Building Panel Market TacticsStress-skin building panels can't beat the cost of conventional building systems. But they are carving out a niche in the market for low-energy houses. Stress skin should be come more competitive since the costs of labor and materials for conventional buildings are increasing faster. Most would agree that stress-skin panels are used to their best advantage in manufactured and pre-cut panelized housing, where the increased material costs are offset by labor savings and quicker scheduling. Enercept pre-cuts homes to the customer's plans. The company supplies a complete system through a dealer/contractor network. Enercept's building construction system is frameless with patented wood and metal connectors for wall and roof stress-skin panels. Vertical loads are picked up by thermally broken studs placed in the panels 4-feet on center. Once the foundation is in, an average house shell can be completed in two or three days, says Enercept's Ken Norberg. Using Stress Skin Insulated Foam Core Panels for Insulated CeilingsThe W.H. Porter Company markets some insulated foam core stress skin panels with a tubular-steel octagonal frame. It's aimed at the recreational and vacation-home market. Most of Porter's panels are sold for roofs of conventional houses, and some for site-built panelized homes. Porter sees great promise for OSB-faced roof stress-skin panels that can san up to 24 feet. "There's no better product," he says, "for cathedral ceiling applications." Northern Energy Homes supplies completely pre-cut house packages - using styrene core foam panels and a simplified timber frame. "Each piece is pre-engineered and pre-cut for each house," says Northern Energy's Richard Clancy. "This way," he says, "we don't leave our technology up to the contractor." The standard package includes such energy amenities as Heat-Mirror windows, integrated night insulation, and ground water heat pumps. Other companies garget specialty markets for stress skin insulated building panels. Several pre-fab sunspaces use foam-core stress-skin panels for end-walls and roof sections. Energy Saving Products, a company that specializes in indoor swimming pool equipment, markets stress-skin insulated panels for swimming pool enclosures. The company's Rita Welebob says urethane panels are viewed as a one-step solution to problems caused by rusty nail heads and soggy insulation. While no figures were available in the 1980's, manufacturers reported rapid growth over the middle of that decade. Enercept's Ken Norberg forecasted growth from 50 to 100 percent per year in stress skin panel use in the mid 1980's. No one speaks as if stress-skin building panels are panaceas. But arguments and rivalry aside, everyone predicts a bright future for the foam core panel system that can provide structural integrity, exceptional energy performance, and freedom from moisture concerns. This article is reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss. In this energy savings article series we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss. List of Producers of Stress Skin Panels for Timber Frame & Structural Insulated Panel HomesCONTACT us to add stress skin and structural insulated panel SIP producers and experts to this list - no fees.
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