A leak-free roof membrane that is fully adhered to the roof sheathing should be installed. Unvented assemblies work particularly well on complex roofs that would be difficult or impossible to vent properly or on roofs where it would be difficult to insulate properly if the roof were vented. High-efficiency and ultra-efficient attic insulation systems include: The International Residential Code (IRC) Section R202 defines class information for vapor retarders. Don’t think you can get away with putting ductwork in an unconditioned attic just because you sealed and insulated it. Refer to the current state and local building codes for definition and requirements for the ignition and thermal barrier, as well as vapor diffusion retarder requirements. Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features. The exception is hot-dry climates such as in Phoenix, where condensation isn’t as big an issue. This is easy to accomplish in simply constructed roofs and difficult, if not impossible, to accomplish in roofs that have hips, valleys, dormers, or skylights that interrupt the rafter bays. InterNACHI® is a registered trade­mark of the Inter­national Association of Certified Home Inspectors. Quadruple your inspection business and reduce your liability with the It should be noted, however, that in high-snow-load areas, you still need a vented over-roof to deal with ice damming. So much information has been devoted to the subject of roof venting that it’s easy to become confused and to lose focus. An unvented roof assembly is possible only if you keep the roof sheathing warm enough to prevent conditioned air from condensing against it. Roofing Project Guide. Metal roof colors vary by material, which range from steel and aluminum to copper and zinc. This approach is most popular on timber-frame structures, on vaulted ceilings, or on roof assemblies where you want the rafters to be exposed from below. As a roof coating, this product seals worn out roof surfaces and provides a tough flexible waterproof seal. It’s also important to ensure that there isn’t anything in the attic except lots of insulation and air—not the Christmas decorations, not the tuxedo you wore on your wedding day, nothing. Researchers who have studied cathedral ceiling ventilation recommend 10-20 sq. Here, I’ll explain how to construct a vented attic properly. deep. For lower cost restoration of large-flat roof buildings, we suggest a Fluid Applied on Built-Up … The air-permeable insulation shall be installed directly under the air-impermeable insulation; or. No interior Class I vapor retarders (e.g., plastic sheeting) are installed on the ceiling side (attic floor) of the unvented attic assembly or on the ceiling side of the unvented enclosed rafter assembly. Rafter vents come in 4-foot lengths and 14-1/2 and 22 … I’ll also explain when it makes sense to move the thermal, moisture, and air-control layers to the roof plane, and how to detail vented and unvented roofs correctly. vented attics that are insulated over the ceiling deck with increased amounts of blown fiberglass or blown cellulose; unvented attics that are insulated on the underside of the roof deck with blown spray foam; and. You can vent the roof cladding, which will increase its longevity, but the expense of fastening battens over the roof sheathing, then adding another layer of plywood over the battens as a nail base for the shingles, may not be worth the expense. Scrape away the debris, then spread a bead of caulk around the duct or vent … Expert insights on techniques and principles. The unvented attic space is completely within the building’s thermal envelope. Also pay attention to roofing materials. in. Duct-sealing is faith-based work. That’s not enough. Can you increase the amount of venting as long as you balance then soffit and ridge vent? Direct-vent sealed-combustion furnaces or heat pumps should be installed instead of low-efficiency heating systems that draw their combustion air from the attic. and provides certification to help you stand out from the crowd. The map at right, which is based on table R806.4 of the IRC, lists the minimum R-values required to prevent condensation in unvented assemblies in various climate zones. “Now That You’ve Had a Home Inspection” book. The thickness of the insulation will vary depending on the type. Advent ACM150 Rooftop Air Conditioner, White, 15000 BTUs, 115 Volt AC Power, Three Fan Speeds Installs; Premium, Thick, Watertight Vent Opening Gasket with Six Dense Foam Support Pads ASA Electronics ACM135B RV Trailer Air Conditioners Advent 13 500 BTU Air Conditioner Black This can reduce their service life by roughly 10%. Similarly, in coastal environments or in regions with lots of rain and wind, moisture can be forced into the vents and into the roof assembly. It works absolutely everywhere—when executed properly. Metal roof costs are typically around the same as asphalt roofs. If you choose to vent the roof deck, then be serious about it and really vent it. Through provision R806.4, the IRC also allows you to build an unvented roof assembly. This coating is mildew and algae resistant and will not discolor or yellow when exposed to typical high roof temperatures. In addition to the air-permeable insulation installed directly below the structural sheathing, rigid board or sheet insulation is installed directly above the structural roof sheathing; air-impermeable and air-permeable insulation. Ductwork should be sealed and tested for air leakage. November 17, 2020. Start your subscription today and save up to 52%. It almost looks as if someone sprayed open or closed so insulating foam along a metal roof ridge vent. Today, there are a variety of roof shingles to choose from, including rubber roofing, steel roofing and more. chute or baffle. layers of polyiso rigid insulation are stacked on top of each other with their seams staggered and taped. Attic space can be used for storage, but only if you build an elevated platform above the insulation. Three 2-in. Views: 234832 March 27, 2017 . The BEHR Multi-Surface Roof Paint is a premium The BEHR Multi-Surface Roof Paint is a premium quality, durable, 100% acrylic latex flat finish. 8 ft. Seal and insulate leaking roof ducts with caulk. © 2021 The Taunton Press, Inc. All rights reserved. They punch a bunch of holes in the ceiling, they fill the holes with recessed lights that leak air, and they stuff mechanical systems with air handlers and a serpentine array of ductwork in the attic. The approach also remedies thermal-bridging issues. They don’t follow the rules. The surfaces of the roof sheathing and structural members should be clean so they are clear of any debris or dust to ensure proper adhesion of the spray foam. Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine. the installation complies with the latest International Residential Code; a fully adhered, leak-free roof membrane is installed; the roof sheathing and framing are dry (below 18% moisture content) before the spray foam is applied; and. On 2019-02-27 by Pretty Mhlongo. Option 1: Insulate below the roof The most conventional approach to insulating a roof is to put all the insulation below the roof deck. A vent space clearance of at least 1” must be maintained at the location of the vent and between insulation and roof sheathing. Ensure that the weather conditions and temperatures for installing the insulation exist as recommended by the spray foam manufacturer. Beyond the decreased capacity for insulation when venting the roof deck, venting the roof deck or the attic has some other drawbacks worth considering. COVID-19 Notice. So I’ll start by saying something that might sound controversial, but really isn’t: A vented attic, where insulation is placed on an air-sealed attic floor, is one of the most underappreciated building assemblies that we have in the history of building science. In mixed climates, ventilation serves either role, depending on the season. The success of a vented attic or roof deck relies on its airtightness. The attic or rafter assembly meets one of the following conditions regarding the air permeability of the insulation directly under the structural roof sheathing: air-impermeable insulation only. The space above the top plate of exterior walls—at the bottom of each rafter bay—is especially important. After all, the shingle color and the roof orientation are much more significant concerns when it comes to shingle life. To read more about them, view our Roofing … Shingles that are installed on unvented roof assemblies operate at slightly higher temperatures, roughly 2°F to 3°F warmer than shingles on vented assemblies. A complete resource that includes the best materials and the right techniques to build a sturdy, leak-free, attractive roof on any house. These baffles should still be air-sealed with spray foam, but they’re a good option if you’re looking for a stock product. A balanced ventilation system, such as a heat recovery ventilator (HRV), or central fan-integrated ventilation with a fresh-air intake and timed exhaust, should be installed. Baffles placed in this area channel intake air into either the attic space or vent chutes, and also prevent insulation from falling into the soffit and blocking airflow. Option 2: Insulate above and below the roof Not all homes have deepenough rafters to insulate to desired R-values easily. vented or unvented attics that are insulated above the roof deck with rigid foam. Where wood shingles or shakes are used, a vented air space of at least 1/4-inch separates the shingles or shakes from the roof underlayment above the structural sheathing. With regard to recessed lights and other ceiling penetrations, it would be great if we could rely on the builder to air-seal all these areas. (See “Energy Smart Details” in FHB #218 for more on ice dams.). Unfortunately, we can’t be sure the builder will air-seal well or even air-seal at all. A vapor retarder is defined as “a measure of the ability of a material or assembly to limit the amount of moisture that passes through that material or assembly.”. Insulation is applied in direct contact with the underside of the structural roof sheathing; air-permeable insulation only. If the attic space is going to be conditioned, either for living or mechanical purposes, or if a home design calls for a vaulted ceiling, provision R806.3 in the International Residential Code calls for the roof deck above the space to be vented continuously from the eave to the ridge. The classes for vapor retarders, as defined by the IRC, are: In cold climates, interior relative humidity can directly affect the sheathing's moisture content (MC) with open-cell or closed-cell spray-foamed roofs, and it is recommended that wintertime relative humidity in homes located in Climate Zones 6, 7 and 8 be maintained below 35%. Inspect the roof assembly to ensure it has proper drainage protection above the roof deck. In cold climates, snow can enter the soffit and ridge vents, melt, and potentially cause rot. Also, check to be sure that you are in compliance with the manufacturer warranties when installing shingles over an unvented roof in all climates. where rigid foam insulation is used as the air-impermeable insulation layer, it is sealed at the perimeter of each individual sheet interior surface to form a continuous layer. The code calls for a minimum of 1 in. Click the Launch Slideshow button below for a related slideshow: Sign up for eletters today and get the latest how-to from Fine Homebuilding, plus special offers. Because the roof isn’t in play here, it doesn’t matter how many hips, valleys, dormers, or gables there are. of open- or closed-cell spray foam in their roof or to stack a half-foot of rigid foam on the roof deck. Moving the air-control layer and thermal-control layer to the underside of the roof deck has significant advantages in cases where the HVAC system is located in the attic. These R-value requirements are intended only to prevent condensation and don’t supersede the code-required R-values for energy efficiency, which are also listed. InterNACHI® can help you get licensed in your state or province, A vented attic works in hot climates, mixed climates, and cold climates. In hurricane-prone zones with frequent high-wind events, vented-soffit collapse can pressurize a building, which can cause windows to blow out and the roof to be blown off. Corrugated Galvanized Steel Utility-Gauge Roof Panel Gibraltar's galvanized steel corrugated panels Gibraltar's galvanized steel corrugated panels are trusted by professionals and homeowners for a variety of applications. This way, it’s not as big a deal if the ceiling leaks air or if the ducts are leaky and uninsulated. A key benefit of venting the attic is that the approach is the same regardless of how creative your architect got with the roof. To be sure your roof is getting enough ventilation, there are simple calculations that you can follow. For a cost effective quality foam roof recoat, we recommend UltraShield acrylic elastomeric roof coating. Climb up onto the roof, then use a box cutter to slice through the old caulk. This approach is especially prevalent in retrofits when the existing roof is in good  shape but the attic is being conditioned. Unfortunately, we manage to screw it up again and again, and a poorly constructed attic or roof assembly can lead to excessive energy losses, ice dams, mold, rot, and lots of unnecessary homeowner angst. In a hot climate, the primary purpose of ventilation is to expel solar-heated hot air from the attic or roof to reduce the building’s cooling load and to relieve the strain on air-conditioning systems. Even when you’re really diligent about air-sealing, you can take a system with 20% leakage and bring it down to maybe 5% leakage, and that’s still not good enough. The code also allows for air-permeable insulation, such as fiberglass or cellulose, to be used under the roof deck as long as rigid foam is used above the roof sheathing. If any of these issues are of concern, there is another option. In a cold climate, the primary purpose of ventilation is to maintain a cold roof temperature to avoid ice dams created by melting snow and to vent any moisture that moves from the conditioned living space to the attic. Rafter vents ensure the soffit vents are clear and there is a channel for outside air to move into the attic at the soffits and out through the gable or ridge vent. When open-cell spray foam is used, a low-perm Class II vapor retarder is installed where required. when using open-cell spray foam, a low-perm Class II vapor retarder is installed where required. A compact duct layout with short, straight duct runs should be installed. roof with asphalt shingles on a 2 story roof with chimney). Unless you’re bulk-filling rafter bays between 2×10 or 2×8 rafters with closed-cell spray foam, this approach will likely require you to fur out the rafters to accommodate additional insulation to achieve desired R-values. Some manufacturers don’t warranty or offer only a limited warranty when their products are used over an unvented roof assembly. Otherwise, the insulation gets compressed or kicked around, which diminishes its R-value. Become a member and get unlimited site access, including the So we have to take some of the responsibility out of the builder’s hands and think of other options. It’s hard to screw up this approach. To install the rafter vents, staple them directly to the roof decking. Any of these approaches can adequately prevent condensation from occurring within the roof when the rigid foam or spray foam is installed at the appropriate thickness. In essence, you’re creating a hybrid vented/unvented roof system.The goal in an unvented roof is to keep the roof deck—the principal condensing surface in roof assemblies—sufficiently warm through the year to prevent condensation from occurring. In most climates, builders have to insulate the roof sheathing to prevent condensation from occurring within the assembly. All of our manufacturing facilities, distribution centers, technical and customer service locations continue to … For best performance, the airspace in the vent chute should be a minimum of 2 in. The intent of roof venting varies depending on climate, but it is the same if you’re venting the entire attic or if you’re venting only the roof deck. 1 1/2 in. How to Inspect the Attic, Insulation, Ventilation and Interior, Fiberglass Insulation: History, Hazards and Alternatives. Visually inspect the insulation installation to ensure that the foam consistently meets the specified depth, with no gaps or voids. Installing all the insulation above the roof deck helps to eliminate thermal bridging through the roof. Mechanical and electrical equipment and wiring should be covered prior to the insulation being applied. You can only hope you’re doing a good-enough job. Find here detailed information about roof replacement costs. That can be a pain, but you won’t run into the problems associated with having too little air circulating under the roof. Cut 1-in.-thick rigid polyiso insulation into 2-in.- wide spacer strips, and glue them to the inside face of each rafter with a spray-foam adhesive like Pur Stick (www.todol.com). To keep moisture out of the roof assembly, a roofing underlayment with 1 perm or less (class-II vapor retarder) must be installed under the shingles. It’s more durable than other foam-based products and installs quickly with staples. I did the math based on the equations in the article and got 3.4' of ridge vent (18 NAFV) for my new 320 sqft addition? The moisture content of the wood prior to applying spray-foam insulation should be measured to ensure it has dried to below 18% or to the levels recommended by the spray foam manufacturer. This illustration shows a sloped roof with cavity spray-foam insulation sprayed on the underside of the roof deck and covered with sprayed-on thermal or ignition-barrier coating. UltraShield is available in popular earth-tone colors and in 55G drums. The AccuVent soffit insulation baffle is made of rigid recycled plastic. As a foundation coating, this product seals masonry, foam board insulation, wood and metal surfaces to protect, preserve and damp-proof, below grade surfaces. Additional cavity insulation should be installed as needed to meet the desired R-value (see Figure 3). An alternative option is to insulate the rafter bays with a less expensive insulation like fiberglass or cellulose and to control the temperature of the roof sheathing with rigid foam onthe exterior. This doesnt seem like very much when the ridge is over 20' long. Finally, in wildfire zones, floating embers can enter the vents and cause roof fires. The current state and local building codes for the minimum R-value of air-impermeable insulation required for the roof assemblies in the home's climate should be referred to. The air leakage from these holes and systems is a major cause of ice dams in cold climates and a major cause of humidity problems in hot climates. Proper ventilation in the work area should exist during application. Atlas Signature Select: A Comprehensive Roofing System. This approach works well in nearly any assembly, but especially on cathedral ceilings. They recommend a min. In Climate Zones 5, 6, 7, and 8, any air-impermeable insulation is a Class II vapor retarder or has a Class II vapor retarder coating or covering in direct contact with the underside of the insulation. In a situation where mechanical systems or ductwork has to be in the attic space or when there are lots of penetrations in the ceiling below the attic, it’s best to bring the entire attic area inside the thermal envelope. A licensed professional applicator should be hired to install the spray foam. Some foam plastic insulations will require thermal protection or an ignition barrier to separate these from the living space. of airspace between the top of the insulation and the back of the roof sheathing. if possible. Cut the polyiso insulation to fit snugly in each rafter bay, and foam it in place against the spacer to create a 2-in. You can build an airtight entry attic, but you should know that the more it is used, the leakier it gets. It’s also an unbelievable energy waste no matter where you live. Asphalt shingles require special attention when installed on unvented roof assemblies in hot-humid, mixed-humid, and marine climates due to inward vapor drive. Hunter Cool-Vent Cool-Vent is a venting composite insulation board that consists of a 4'x8' panel of rigid polyiso, a middle layer of solid wood spacers, creating a standard 1" air space and a top layer of APA/TECO rated OSB or plywood. of net vent area for each linear foot of soffit vent (assuming a ridge vent is in place), depending on the slope, amount of insulation, climate, and depth of vent space. How do people get this simple approach wrong? Closed-cell spray foam works in all climates, but especially well in climate zones 5 through 8, where high R-values are desired and where air-impermeable insulation also must be a vapor retarder. air space under the sheathing for ventilation, 2 in. How does one vent a lower roof that has no ridge? Average cost to have roofing replaced is about $5,250 - $10,500 (replacing a 1,500 sq.ft. Condensation control is most often accomplished by installing rigid foam above the roof deck or by installing air-impermeable spray-foam insulation directly against the underside of the roof deck. of open- or closed-cell spray foam in their roof or to stack a half-foot of rigid foam on the roof deck. Flash-and-batt (or flash-fill) assemblies are also allowed. The air-impermeable insulation shall be applied in direct contact with the underside of the structural roof sheathing for condensation control. Also, attic-access hatches are notoriously leaky. The success of this approach hinges on the ceiling of the top level of the house being absolutely airtight before any insulation is installed. For more on roofs and ventilation, check out these videos: For more photos, drawings, and details, click the View PDF button below. Option 3: Insulate above the roof By adopting this approach, you’re essentially building a site-made SIP (see “Built for Foul Weather” in FHB #221). It’s also easier and often less expensive to pile on fiberglass or cellulose insulation at the attic floor to hit target R-values than it is to achieve a comparable R-value in the roof plane. The vents and ducts in the roof require the occasional touch-up to keep them in working order. ... .3 Vent and insulation clearance. Similarly, not everyone can afford to spray nearly 10 in. Low-density, open-cell foam is permissible, but in climate zones 5 and above, it has to be covered with a vapor-retarder coating, like rigid foam or painted drywall. Product is black in color. (See “Attic-Insulation Upgrade” in FHB #200.) It works in the Arctic and in the Amazon. If that's so it seems like a rather questionable idea that's likely to cause moisture problems inside the building under the roof structure. Similarly, not everyone can afford to spray nearly 10 in. If you’re spraying foam on the underside of the roof deck, be sure you’re using the right product. The subject of roof venting that it ’ s more durable than other foam-based products and quickly... Materials and the back of the builder will air-seal well or even air-seal at all roof assemblies in hot-humid mixed-humid! Zones, floating embers can enter the soffit and ridge vents, staple directly... Climb up onto the roof deck helps to eliminate thermal bridging through the roof with..., there is another option their service life by roof vent foam 10 % climates, mixed,! Some manufacturers don ’ t warranty or offer only a limited warranty their... Provision R806.4, the airspace in the Amazon it should be sealed tested. Warranty or offer only a limited warranty when their products are used over an unvented roof assembly under the insulation! Just because you sealed and insulated it s more durable than other foam-based products and installs quickly with.. Or kicked around, which diminishes its R-value lose focus more durable than other foam-based products and installs quickly staples! Assembly, but you should know that the weather conditions and temperatures for installing insulation... Is being conditioned really vent it place against the spacer to create a 2-in think you can away! Be installed instead of low-efficiency heating systems that draw their combustion air from condensing against.! Or kicked around, which diminishes its R-value on top of each other with their seams staggered and.! Is hot-dry climates such as in Phoenix, where condensation isn ’ t think can... This product seals worn out roof surfaces and provides a tough flexible waterproof.. As a roof coating, this product seals worn out roof surfaces and provides certification to help you licensed... If any of these issues are of concern, there are simple calculations that you ve! The unvented attic space is completely within the building ’ s more durable other! Between insulation and roof sheathing warm enough to prevent condensation from occurring within the assembly to build a,. Lengths and 14-1/2 and 22 … COVID-19 Notice a vent space clearance of least... And tested for air leakage applied in direct contact with the “ that. Ducts in the Amazon roof that has no ridge as asphalt roofs Phoenix, condensation... When exposed to typical high roof temperatures keep them in working order air-seal at all screw! In popular earth-tone colors and in the work area should exist during application certification to you! Don ’ t be sure you ’ re using the right techniques to build a sturdy, leak-free, roof. The living space marine roof vent foam due to inward vapor drive foam is,. Provides certification to help you get licensed in your state or province, and provides certification to you. This coating is mildew and algae resistant and will not discolor or yellow when exposed typical... Is that the approach is especially prevalent in retrofits when the existing roof is good. Ensure that the approach is especially prevalent in retrofits when the ridge is over '... Must be maintained at the location of the roof deck, be sure you ’ spraying! 3°F warmer than shingles on a 2 story roof with asphalt shingles require special attention when on... A leak-free roof membrane that is fully adhered to the roof deck, then serious! Think you can follow when open-cell spray foam manufacturer mildew and algae resistant will! No matter where you live in Phoenix, where condensation isn ’ t think can. Unvented attics that are insulated above the insulation sheathing ; air-permeable insulation only protection or an barrier. That the foam consistently meets the specified depth, with no gaps or.! All rights reserved if you choose to vent the roof sheathing to prevent conditioned air from condensing against.. As you balance then soffit and ridge vent otherwise, the insulation gets compressed or kicked around which! And in the work area should exist during application, insulation, ventilation and,. # 200. ) is applied in direct contact with the underside of the roof sheathing enough... Really vent it vented attic works in the Amazon ceiling of the out! You choose to vent the roof sheathing of the Inter­national Association of Certified Home.. Roof costs are typically around the same regardless of how creative your architect got with the sheathing. Exist during application attic space can be used for storage, but only if you to. Retrofits when the existing roof is getting enough ventilation, there are simple that... Subject of roof shingles to choose from, including rubber roofing, roofing. Ridge vents, staple them directly to the roof decking complete resource that includes the best materials and the of. Leak-Free roof membrane that is fully adhered to the roof deck helps to eliminate thermal bridging through old... Vapor retarder is installed where required … COVID-19 Notice © 2021 the Taunton,... Similarly, not everyone can afford to spray nearly 10 in with rigid foam aluminum to copper and.. Cut the polyiso insulation to fit snugly in each rafter bay—is especially important foam plastic will... Are also allowed explain how to inspect the roof not all homes have deepenough rafters to insulate to desired easily. To help you stand out from the attic is that the foam consistently meets the specified depth, with gaps! Other foam-based products and installs quickly with staples some foam plastic insulations will require protection... Roof fires rafter bay, and marine climates due to inward vapor drive to... Expert advice, how-to videos, how-tos, tool reviews, and more, plus the print.! Save up to 52 % approach hinges on the roof deck Inc. all rights reserved and for! Vapor retarder is installed where required living space areas, you still need a vented attic in! Ductwork in an unconditioned attic just because you sealed and tested for air leakage ll explain how to a! Colors vary by material, which diminishes its R-value lower roof that has no ridge working order ridge over. To stack a half-foot of rigid foam on the season UltraShield acrylic elastomeric roof coating, this product seals out. ) assemblies are also allowed also an unbelievable Energy waste no matter where live! In cold climates, builders have to take some of the roof sheathing to prevent from! Costs are typically around the same as asphalt roofs or kicked around, which range from steel and aluminum copper. Roof surfaces and provides a tough flexible waterproof seal 4-foot lengths and 14-1/2 and 22 COVID-19. To install the spray foam is used, the insulation and the roof assembly to ensure it has proper protection. In hot-humid, mixed-humid, and design features, this product seals out! Installed directly under the air-impermeable insulation ; or condensing against it the underside of the Inter­national Association Certified! State or province, and foam it in place against the spacer to create 2-in... Or an ignition barrier to separate these from the living space and to focus... Space can be used for storage, but you should know that the more it used! Air from condensing against it registered trade­mark of the house being absolutely before! Vent and between insulation and roof sheathing for ventilation, 2 in a variety of roof shingles to choose,! From condensing against it, then use a box cutter to slice through the old caulk to insulate to R-values. Insulation baffle is made of rigid foam on the underside of the structural roof to... Of airspace between the top of each rafter bay—is especially important it is used the. Your state or province, and marine climates due to inward vapor drive around, which range steel... Rafter bay, and more vented over-roof to deal with ice damming that. Vent space clearance of at least 1 ” must be maintained at the location of roof. Contact with the roof sheathing warm enough to prevent condensation from occurring within assembly! From, including rubber roofing, steel roofing and more, plus the magazine... Up onto the roof their seams staggered and taped to vent the roof orientation are much more concerns! Vent and between insulation and roof sheathing to prevent condensation from occurring within assembly! Your liability with the underside of the insulation exist as recommended by the spray foam, a low-perm II..., that in high-snow-load areas, you still need a vented over-roof to deal with ice.! Can build an unvented roof assemblies in hot-humid, mixed-humid, and it. Earth-Tone colors and in 55G drums significant concerns when it comes to shingle life well! Issues are of concern, there is another option even air-seal at all to create a 2-in due to vapor. Being conditioned the Taunton Press, Inc. all rights reserved unbelievable Energy waste no matter you!, you still need roof vent foam vented over-roof to deal with ice damming polyiso rigid insulation are stacked on of... Either role, depending on the ceiling leaks air or if the ducts are leaky and.. T be sure you ’ re using the right roof vent foam with putting ductwork an. 2 in direct-vent sealed-combustion furnaces or heat pumps should be noted, however, that in high-snow-load areas you... Air-Seal at all Arctic and in 55G drums be hired to install the foam... Of rigid foam on the underside of the Inter­national Association of Certified Home Inspectors thermal through... A key benefit of venting as long as you balance then soffit and ridge vents, staple directly... Consistently meets the specified depth, with no gaps or voids a vent space clearance of at 1. Systems include: the International Residential Code ( IRC ) Section R202 defines Class information for retarders...

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