ICF vs Spray foam
- Thread starter madera
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Ken Nagrod
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One of the benefits of being in the carpenters union is keeping up with the newest and best building practices. Insulated concrete forms plus the use of spray foam insulation will give you the benefits I believe you're searching for, as long as the installation is done properly.
I would check out this site as it is research based: http://www.buildingscience.com/ In particular check out their information section and go to wall assemblies, etc. You can spend hours days perusing this site and reading through the content.
Personally, for my own home I chose conventional 2 x 6 frame sheathed with OSB, then 1" styrofoam taped at all seams in attempt to eliminate wind penetration. Insulated stud cavities with NuWool as it will dry to the inside of the home if any condensation or moisture makes its way into the cavities (so long as walls are painted with latex paint that can "breathe". Through my own research and personal philosophy, I think this is the way to go over spray foam as it is less expensive and blocks heat transfer through the studs as well. ICF's might be even better, but I went with stud framing because it is what I know and could do myself efficiently.
Foundation is 8" block with 1 1/2" styrofoam applied to exterior right up over the rim joist creating a smooth transition with foam sheathing on stud walls... applied to the exterior of block so that any moisture, if any, could dry to the warmer inside. Energy code in my region of Michigan now calls for R15 so if doing it again would go with ICF's to meet this code. However, at the time block was considerably less expensive, including the foam - although there was no energy code for basement so the styrofoam was a personal decision and relatively inexpensive up front for quite a bit of bang for my buck in terms of potential energy savings, especially with the rim joist insulated from the outside.
Personally, for my own home I chose conventional 2 x 6 frame sheathed with OSB, then 1" styrofoam taped at all seams in attempt to eliminate wind penetration. Insulated stud cavities with NuWool as it will dry to the inside of the home if any condensation or moisture makes its way into the cavities (so long as walls are painted with latex paint that can "breathe". Through my own research and personal philosophy, I think this is the way to go over spray foam as it is less expensive and blocks heat transfer through the studs as well. ICF's might be even better, but I went with stud framing because it is what I know and could do myself efficiently.
Foundation is 8" block with 1 1/2" styrofoam applied to exterior right up over the rim joist creating a smooth transition with foam sheathing on stud walls... applied to the exterior of block so that any moisture, if any, could dry to the warmer inside. Energy code in my region of Michigan now calls for R15 so if doing it again would go with ICF's to meet this code. However, at the time block was considerably less expensive, including the foam - although there was no energy code for basement so the styrofoam was a personal decision and relatively inexpensive up front for quite a bit of bang for my buck in terms of potential energy savings, especially with the rim joist insulated from the outside.
Dane
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I have worked with all of these methods at some point, along with others- strawbale, rammed earth etc....I built my last home out of Structural Insulated Panels (SIPs) and could not have been happier. They are cut in the factory and you assemble them on-site like a big jigsaw puzzle. Structure, insulation and sheathing in one shot. Faster than any other method and twice as strong as stick built. Properly installed, they will give you an extremely tight house with little thermal bridging. That said, stickbuilt with either a double stud wall or exterior rigid foam and blown cellulose is also a great way to go. Most folks are now leaning away from using spray foam for the wall cavities- it is expensive and if you get any water intrusion, you can have problems. Roofs- it is a great product. Walls- cellulose and exterior rigid foam is often a better and always a less expensive choice. ICFs can be good, but time consuming and tricky to do unless you really know what you are doing- pouring that much concrete and getting the bracing right requires experience.
If you go to the JLConline forum and browse the Building Science section, you will find a lot of good info. I second BuildingScience.org as a great site for info on all kinds of wall assemblies.
If you go to the JLConline forum and browse the Building Science section, you will find a lot of good info. I second BuildingScience.org as a great site for info on all kinds of wall assemblies.
Ken Nagrod
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Dane,
Polyurethane spray foam has always been the more expensive option, but nothing seals better because, properly applied, it finds every nook and cranny and fills it. The closed cell foam (more expensive than open cell) gives a high R value (R6/inch) and has great water resistance and structural assistance as well. The open cell foam is like a sponge with air pockets that don't insulate as well (R3.5/inch), however it's for that reason that it seems to trap sound better than closed cell foam. SIPS are good, but keep in mind that when cutting or notching them for electrical or plumbing as an example, no horizontal cuts or channels or you've killed the strength of the panel. That goes for both during construction and later on down the road should the homeowner want to make some changes to their house.
Polyurethane spray foam has always been the more expensive option, but nothing seals better because, properly applied, it finds every nook and cranny and fills it. The closed cell foam (more expensive than open cell) gives a high R value (R6/inch) and has great water resistance and structural assistance as well. The open cell foam is like a sponge with air pockets that don't insulate as well (R3.5/inch), however it's for that reason that it seems to trap sound better than closed cell foam. SIPS are good, but keep in mind that when cutting or notching them for electrical or plumbing as an example, no horizontal cuts or channels or you've killed the strength of the panel. That goes for both during construction and later on down the road should the homeowner want to make some changes to their house.
Sparktrician
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Dane said:
I've worked on strawbale and rammed earth homes before, and thought both to be over-labor-intensive. I've worked on one panelized SIP home and think it's the best thing going for efficiency, accuracy and consistency of construction. Properly sealed as the SIPs are erected, these houses are wonderful. Strawbale homes are somewhat quieter due to the thickness, but so what? For my money, a SIP home over timberframe is the best combination.
[smile]
Wonderwino
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If you have the equipment and training, ICFs have the best structural integrity of all the above methods. After Katrina, ICF buildings were among the only left standing in hard hit areas. Here in tornado alley, a "safe room" can be added by installing a concrete ceiling over an interior ICF room in a slab-on-grade home.
Doors and windows must be properly bucked before pouring concrete and utility sleeves should also be installed. With the proper rebar, they can be built to 140mph wind loading! Cutting in electrical and plumbing does not affect wall strength. This can be done with a hot knife, electric chainsaw or router. Sheet rock applied over the interior is rock-solid as it is fully supported. You ain't gonna punch a hole in these walls!
I am familiar with Logix (logixicf.com) which go together like legos. They have poly webbing for fasteners on 8" centers and come in a wide variety of core widths, heights and shapes. A 60' x 150' x 14' warehouse with peaked ends and perhaps a dozen openings was framed and poured in 4 days with a crew of 4 near here. You've got to have a boom truck deliver the concrete. They went with steel roof trusses, roofing and siding. Looks like any other steel building, but absolutely quiet inside.
They do cost more than conventional framing, but the added cost is recovered in utility savings in 4-5 years, depending on climate. They are also bulletproof for high crime areas. [eek]
Doors and windows must be properly bucked before pouring concrete and utility sleeves should also be installed. With the proper rebar, they can be built to 140mph wind loading! Cutting in electrical and plumbing does not affect wall strength. This can be done with a hot knife, electric chainsaw or router. Sheet rock applied over the interior is rock-solid as it is fully supported. You ain't gonna punch a hole in these walls!
I am familiar with Logix (logixicf.com) which go together like legos. They have poly webbing for fasteners on 8" centers and come in a wide variety of core widths, heights and shapes. A 60' x 150' x 14' warehouse with peaked ends and perhaps a dozen openings was framed and poured in 4 days with a crew of 4 near here. You've got to have a boom truck deliver the concrete. They went with steel roof trusses, roofing and siding. Looks like any other steel building, but absolutely quiet inside.
They do cost more than conventional framing, but the added cost is recovered in utility savings in 4-5 years, depending on climate. They are also bulletproof for high crime areas. [eek]
Thanks for all the great opinions. For those of you with experience building with SIPS or ICF. How does exterior wall electrical go in. Someone referanced knotching into the ICF? With the sips I understand they will fabricate chases in at the factory, but I like to kinda wing the electrical and make changes as I go. The only way I can see that this will be possible would be to strap the walls. Seems like a lot more wrk and hassle.
Wonderwino
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The Logix forms have 2-5/8" of foam on each side of the core with the webbing embedded 1/2" beneath the surface on the outsides. The same methods can be used both inside and outside the structure to run electrical - cutting in as above.
Around here, commercial code requires conduit or armored cable, the latter of which can be installed in a shallower dado. Conduit may require cutting into the embedded poly webbing, but this will not affect the structure of the wall. Wire shields can be screwed over the conduit to the webbing, holding it in place.
Around here, commercial code requires conduit or armored cable, the latter of which can be installed in a shallower dado. Conduit may require cutting into the embedded poly webbing, but this will not affect the structure of the wall. Wire shields can be screwed over the conduit to the webbing, holding it in place.
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