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What are the advantages of SIPs?
- SIPS can be installed in much less time than a site built stud frame. This reduces site labor costs, pilferage, carrying costs and exposure to the weather.
- SIPS offer superior strength and security.
- SIPS provide superior insulating qualities. The foam core of the panel provides a much higher R-value in less space than fiberglass or cellulose insulation and maintains this performance indefinitely.
- SIPS inherently have significantly less air infiltration. The solid foam core and general absence of studs provide an almost foolproof method of creating a tight building envelope. The built-in wiring chases also eliminate air infiltration at this common leakage point.
- SIPS provide structure, sheathing and insulation in one component. This reduces the number of subcontractors required, supervision costs, and administrative overhead.
- SIPS are kinder to the environment. SIPS use engineered wood materials for most requirements and use less dimensional lumber as a whole. This significantly reduces the need for old growth timber. The panel's foam core is recyclable, thus reducing the need for raw material and reducing the amount of material reaching our landfills. Construction material waste is a major component in landfill volume.
Can you adapt SIPs to an existing plan?
- Yes, Floor plans are probably the most flexible element is SIP design. SIPs used in the roof system can provide full volumetric usage of interior space, thus offering the opportunity to create exciting cathedral ceilings and use otherwise lost space for lofts and heated storage space.
What type of foam insulation do we use?
- Our standard panels have a core of Modified Expanded Polystyrene (MEPS). MEPS provides higher R-values per dollar than other types of foam and does not contain chlorofluorocarbons (CFCs), which are believed to damage the Earth's ozone layer. The R-value of MEPS panel cores are extremely stable. In field testing over a number of decades MEPS has been shown to retain virtually all of its original thermal and physical properties. In fact, foam has a unique Thermal Warranty. Another advantage is the fact that the insulative value of MEPS actually increases as the temperature drops. The opposite occurs with fibrous insulation.
What is the difference between Exterior and Exposure 1 rated sheathings?
- Exterior rated sheathings have a fully waterproof bond and are designed for applications subject to exposure to the weather or to moisture for its entire service life. Exposure 1 rated sheathings, either OSB or Plywood, have a fully waterproof bond and are designed for applications where construction delays may be expected prior to providing protection.
- Exposure 1 rated sheathings are made with the same exterior adhesives used in Exterior rated sheathings. However, because other compositional factors may affect bond performance, only Exterior rated sheathings should be used for permanent exposure to the weather. SIPs are not to be used in applications where they will be used for permanent exposure to the weather. A rain screen must be used in conjunction with all siding materials. An acceptable rain screen is any non-perforated housewrap installed per the manufacturer's recommendations or 15# or 30# asphalt impregnated building felt installed shingle style with a minimum 4" lap.
- Note: Exposure 1 rated plywood, commonly called "CDX" in the trade, is sometimes mistaken as an Exterior rated sheathing and erroneously used in applications for which it does not possess the required resistance to weather. "CDX" should only be used for applications as outlined under Exposure 1 above.
Do the panels insulate better than stud walls filled with fiberglass batts?
- Yes. When evaluating the insulating performance of a wall system, several factors should be considered. Most common among these is "R-value." R-value is the measurement of the ability of different materials to resist conductive heat transfer (movement of heat through solid material). The higher the R-value of an insulating material, the better it is able to resist heat loss or gain.
Is R-value alone insufficient for evaluating a wall's performance?
- Yes. All the insulation in the world will have little effect if it is installed in such a manner that air can leak through. Even in an otherwise well insulated buildings, many small leaks can allow large volumes of air to infiltrate the structure. Wind increases infiltration rates as well as convective heat loss (wind chill effect).
- Moisture condensation is another area of concern with fibrous insulation. In the past few years there has been growing concern about the effects water vapor has on wall systems in tightly constructed buildings.
- The theoretical basis for this concern is as follows: vaporized water generated by daily living activities penetrates the interior sheathing (usually drywall) and enters the wall cavity. As the vapor contacts the cold outside wall, it can condense into actual water droplets which create the potential for mold or mildew, blistering paint, degraded insulation and even structural damage due to rotten studs.
- The degree to which these concerns are realized depends upon the tightness of the structure. Moisture condensation in older, more loosely built structures has not been a large concern because water vapor could readily escape along with the heated air. In a tighter, energy conscious building those escape routes are more likely to be blocked, creating the potential for problems.
- Weather or not there is damage to structural materials depends upon their composition, but there is another potential problem. The condensed water can saturate the insulating material, thereby increasing the conductivity (reducing its R-value) and causing considerable heat loss. Even relatively small amounts of moisture in fiberglass and cellulose insulations are known to significantly reduce their insulation capabilities.
- In an attempt to prevent this, vapor barriers are installed. These barriers can be created with many different materials, so long as they restrict (though not eliminate) the water vapor that passes through.
- So, in order to evaluate the insulating performance of a given wall system, it is important to consider the tightness of construction, the R-value of the materials, the quality of the installation, and the wall's susceptibility to moisture condensation.
How do foam core panels help these problems?
- First, MEPS has an R-value of 4.35 per inch of thickness at 25°F. The typical panel we use has 5-5/8 inches of foam in its core (R-26); this is the composite panel calculated R-value at 25° F.
- Second, the panels are manufactured in large sheets (4'X8' up to 8'X24') consisting mostly of insulation. The seams are sealed, creating continuous blanket insulation uninterrupted by structural framing members (as opposed to a conventional stud wall with a break in the insulation ever 16 inches to accommodate framing lumber).
- Removing the framing lumber from the insulation allows full utilization of the MEPS. Remember, wood is relatively poor insulator (R-1 per inch of thickness), and in a wall with studs every 16 inches, wood can account for up to 30 percent of a wall's volume, significantly reducing the overall performance of the wall. The stated R-value of an panel is a true reflection of its ability to resist conductive heat loss.
- Third, in panels the continuous mass of high density foam nearly eliminates the air movement within the wall and the heat loss caused by convective looping of air within the insulation. Compare the continuous mass of MEPS to a low density insulator such as fiberglass. Fiberglass is the material used to make filters for face masks, furnaces and cigarettes because it allows air to pass through.
- Fourth, MEPS foam is only marginally affected by moisture condensation. In one test, MEPS was force saturated to ten times its normal dry weight and still retained 80% of its insulating value. In addition, MEPS insulation is inert, organic material. It provides no food value to plants, animals and microorganisms. It will not rot and it is highly resistant to mildew.
I am building in a wooded area. Could I have a problem with carpenter ants?
- Possibly, if you build your nest in ant territory they might build their nests in yours. Unlike termites, carpenter ants do not eat wood, they just burrow in it, and the softer the wood, the easier the work. That's why they like moist, rotting limbs and stumps.
- Given the opportunity, carpenter ants may also tunnel into the foam insulation in wall and roof panels as they will in fiberglass and cellulose insulations. The resulting damage is often negligible, but left unchecked, these ants can dig out enough insulation to reduce the thermal effectiveness of the panel and conceivably affect its structural performance.
- Preventing carpenter ant infestation in any structure is easier than curing it and prevention is most easily done during construction. Use pressure treated lumber for the sill and other areas subject to dampness. Leave a 2-foot buffer zone between the house and surrounding vegetation, and protect against "aerial attack" by trimming back any overhanging tree limbs. Seal and periodically check all potential entry points. Clear away any natural nesting materials such as dead trees and downed limbs, and store firewood well away from the house.
- In areas that are particularly prone to ant problems such as heavily wooded areas or low shaded areas where the ground stays damp, consider treating the foundation with a long-acting pesticide prior to backfilling and install termite shield under the sill. Consult a local treatment expert for further recommendations on long term control methods for your area.
- Be equally inhospitable inside the house. Ants don't eat wood or insulation; they eat things like food scraps, garbage and insects, and will be much less attracted to a clean house.
- Control indoor humidity with an active ventilation system. Excessive humidity causes condensation which can soon result in moist, rotting wood - just what ants like.
Will MEPS give off toxic gases in my home?
- No. MEPS begin as tiny styrene beads that are impregnated with liquid pentane- a colorless hydrocarbon which does not cause any health problems except at high levels of concentration.
- When heat and steam are applied to the beads, the pentane causes them to expand to more than 30 times their original size (when the plastic is in its bead form, pentane accounts for about 6 percent of the material by weight). During the expansion process, this drops to about 3 percent, and within 6 weeks to 2 months after cutting pentane content declines to less than one-quarter of one percent. By the time of occupancy, the pentane content is negligible. MEPS contain no formaldehyde.
Is EPS a fire hazard?
- We use "Modified EPS" which contains flame retardant additives that improve its burning characteristics compared to the EPS variety we are so familiar with in our disposable cups and packaging materials. EPS products will progressively distort, soften and melt when exposed to temperatures in excess of 175°F. As exposure temperatures continue to increase, combustible gases given off by molten residue will ignite in the presence of an ignition source. This temperature level, referred to as the flash ignition point, is approximately 700°F for modified EPS. This value may be directly compared to flash ignition temperatures for white pine and Douglas fir of 500° F.
- Unlike wood, however, MEPS makes a very small fuel contribution because it contains only about 3% combustion material by volume.
- In addition, most building codes require interior wall and ceiling surfaces covering foam insulations to provide a 15-minute rated fire barrier. panels meet this requirement with the installation of drywall on interior surfaces.
Do SIP homes require special foundations?
- NO. They can be built on block, poured, slab, pier or treated wood foundations.
What about interior walls?
- Interior walls are built using studs in the conventional manner.
How are windows and doors installed in foam core panels?
- Windows and door openings can be cut during installation of panels. Rough framing is installed after moving 1-1/2" of foam around the perimeter of the opening. The window or door unit is then shimmed in place and secured according to the manufacturer's instructions. The gaps between the rough opening and the window frame are foamed to eliminate air leakage. An even more efficient method is to have the panels pre-cut for window and door openings and gable, rake and other cuts. This significantly reduces site time and labor and gets the structure out of the weather more quickly.
What kind of siding can be used?
- Any type of conventional siding can be used. The OSB laminated to the panel provides a sound nailing base for attaching siding. With the addition of a brick ledge to the foundation, brick and stone can also be used.
What kind of roofing can I use?
- SIP homes require no special roofing materials. Fiberglass, asphalt, wood and metal are all suitable, but check the manufacturer's warranty before you buy fiberglass or asphalt shingles. Some shingle manufacturers have been hesitant about warranting their product when applied to un-vented roof systems, claiming that un-vented roofs could produce high shingle temperatures and thereby reducing shingle life. However, recent studies at the University of Illinois and the Florida Solar Energy Center concluded that roof ventilation has little or no effect on shingle or sheathing temperature (Energy Design Update, Nov. 1990). This has not produced an overnight change in all shingle makers' warranties, but shop around. There are several shingle manufacturers that offer full warranties on both vented and un-vented roofs.
- Asphalt shingles must meet ASTM D3462, the Specification for Asphalt Shingles Made fro Glass Felt and Surfaced with Mineral Granules. Or ASTM D225, the Specification for Asphalt Shingles (Organic Felt) Surfaced with Mineral Granules. Asphalt Saturated Felt Paper must meet ASTM D226.
How does one install electrical wire in foam core panels?
- Wiring a foam core wall is not difficult but does require planning. Much of the wiring will be run in the conventionally framed interior walls, but there will certainly be some wiring in the panelized exterior walls. Our wall panels are manufactured with a wire chase as specified height above the sub floor (usually 14"). Wire chases can also be located a counter height for kitchen outlets. The wire can be accessed by cutting outlet openings just above the chase. Vertical chases can be provided, but are often not needed because the wire can be run along a door opening or through interior wall framing.
What about plumbing?
- Plumbing is not normally run through foam core panels. The panels are used for exterior walls, and as in consistent with good building practice, plumbing should be kept out of exterior walls to avoid freezing.
What kind of heating system can I use?
- SIP homes require no special heating system. Forced air, electric, solar, radiant and wood burning systems are all suitable, though some are more appropriate than others for a specific home design. Keep in mind that central air conditioning requires ductwork and is therefore most compatible with forced-air heating systems. Because of the home's tight construction, the fireplaces, wood burners, furnaces and any other combustion appliances should be supplied with an outside source of combustion air. No matter what type of system you choose, the home's inherent energy efficiency means you won't need as big a unit as you would with a typical conventionally framed building of equal size.
Do I need to make special provisions for ventilation?
- Yes. A properly constructed SIP home has a very low air infiltration rate. That's great for reducing heating and cooling costs, but it isn't always healthy for the home or its occupants. We strongly recommend that a whole-house ventilating system be installed at the time of construction, and certainly before the first heating season. New homes are filled with new materials and many of those new materials - whether construction products, furnishings or finishes - will out gas various pollutants. Emissions will decrease with time - many products are stabilized within 6 months of manufacture - but extra ventilation may be needed in the meantime.
- The substance that is released in the greatest quantity is water, especially from masonry and the lumber. The materials in the average home contain thousands of gallons of water, which must eventually be removed from the house. The first heating season is typically when the greatest amount of moisture is driven from the house. The first heating season begins as soon as the house is closed to the winter during construction. One telltale sign of lack of adequate ventilation can show up in the form of heavy condensation on windows, or in the ridging of asphalt shingles or in telltale frost or ice at leakage points. Left unchecked, this moisture can produce mold or mildew and can eventually cause serious damage to your home and its contents.
- Ventilation is important even after the home and its contents have stabilized. Significant "indoor pollution" is produced by everyday activities such as cooking, cleaning, bathing and even breathing. It is wise to monitor indoor humidity levels for they are a general indicator of indoor air quality. Most building scientists today recommend that interior humidity levels be maintained at a range of 30% to 50% to minimize health and structural problems.