Rigid foam vs. spray foam under crawlspace
niwashikun
11 years ago
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david_cary
11 years agolast modified: 9 years agoniwashikun
11 years agolast modified: 9 years agoRelated Discussions
XPS under radiant floor? open vs. closed-cell spray foam walls?
Comments (2)For soundproofing, use soundproofing materials--either constrained layer damping drywall, such as Quietrock brand or multiple drywall layers and Green Glue. Before the constrained layer drywall was invented, I used multiple layers on resilient channel. Lots of labour that can be easily short-circuited by just one wrong fastener, research shows....See MoreBest way to insulate between studs with rigid foam
Comments (11)1) If I use cap nails, won't that making the insulation less effective because of the holes? the nails have a plastic cap that will give you a decent seal and will cover the hole left by the nail. as you are nailing into a solid surface (wood) and foam coveres gaps in siding its a non issue as long as you caulk the sides to the studs. 2) energy rater, can you confirm what nerdyshopper said about leaving space between the foam and the drywall? his was a conditioned space application. in homes foamboard can't be left exposed, it has to be behind a fire rated surface like drywall. in his application they used a foil sided foamboard and I guess the radiant barrier (foil) is facing the inside of the wall, putting anything in contact with a radaint barrier is a no no as it doesn't allow the rb to reflect the heat. we put it on exterior walls withthe foil facing the brick, but not to the interior of the wall. yours is a shed.if you plan on finishing the wall out..use a dow blue board and insulate the walls with batts and install sheetrock over them..if its a fancier shed..are you planning on heating and cooling the shed? spending a lot of time in there? what is your location? there is a vapor barrier location criteria. oh and radiant barriers are for hot climates. 3) Any technique for an efficient way us cutting the foam to size so it's gonna be as airtight as possible on irregular shaped dimensions? --> The dimensions are never rectangular. Sides are like: 27" 3/8, 44" 1/4, 28" 1/8 and 43" 3/4 with odd angles. Yep, time and straight edge, and extra razors for the razor knife. cut each to fit tightly and if its too small cut a slice of foam board make it tight fit and nail in place with button cap nails seal with caulk. So you mean caulk every single place where the foam meets the studs? Is it really gonna improve the insulation? exactly. what you are trying to do is make the space comfortable enough to work in. foam sheathing will stop the air flow. if you install it with gaps you will have lots of air infiltration. this is the tradeoff...you do the install of foam sheathing material cost and time or hire a foam company for higher cost and less time. a shop is a diy imo. caulk is cheap. foamboard is easy to work with. insulation doesn't perform because of the air that moves thru it. stop the air movement and it makes a huge difference. how do you plan to finish the ceiling?...See MoreIcf vs rigid foam basement foundation? R value and cost
Comments (17)We built all-ICF in upstate SC, and the performance is remarkable in our fairly mild climate. Given the same foam thickness, either method should perform about the same. The only big advantage I can see for ICF is that it has fastening strips embedded for attaching drywall and exterior siding, if desired. I think ICF does best in moderate climates, with performance falling off at the extremes of temperature. While building our house, I measured the core temperature during the coldest part of winter, and it was about 13 C. (55 F.). I imagine in a very cold climate, it would be much lower than that. Our small house has about 100 tons of concrete in the walls. I'd hate to try to heat that significantly. Here, our ground doesn't freeze more than a couple inches. Our winter design low is -7 C. (20 F.), and in the summer, it is often 34 C. (93 F.), occasionally much warmer, and rarely gets below -18 C. (0 F.) in the winter, and is almost always above freezing during the day. I read an article measuring the true R- performance of ICF in different temperatures. During the shoulder seasons, when temperatures are rather mild, it can perform as high as R-66, while the 'true' R-value is R-24. That's why you sometimes see inflated claims as to its performance. For a very cold climate, you'd want extra foam on the outside of the foundation, plus careful attention paid to isolating the concrete core from the cold ground temperatures. They do make ICF with different thicknesses inside and out....See More2x4 vs 2x6 exterior studs with spray foam insulation. Better Option?
Comments (49)Michigan occupies building climate zones 5 - 7. Zone 5 is the warmest zone that can still comply with the R20 cavity-only requirement. It looks like Ontario has adopted similar IRC mandatory exterior insulative sheathing. We use the performance compliance path on every home, one of the many advantages to including a third party energy rater. Most raters are not keen on getting too far away from code prescriptions. For some of the prescriptions, like blower door minimums, it's cost-effective to exceed code. Most high performance builders are exceeding code with exterior insulation as code encourages risky wall strategies, hence the recommended minimum table I first posted about. Even leaky, all natural homes can have poor indoor air quality. Outdoor air ventilation is now required by current IRC codes and a smart idea for any inhabited enclosed space. It's a life-safety requirement and long overdue measure for modern homes....See Moredavid_cary
11 years agolast modified: 9 years agoenergy_rater_la
11 years agolast modified: 9 years agoniwashikun
11 years agolast modified: 9 years agoenergy_rater_la
11 years agolast modified: 9 years agoniwashikun
11 years agolast modified: 9 years agoenergy_rater_la
11 years agolast modified: 9 years agoweedmeister
11 years agolast modified: 9 years agoenergy_rater_la
11 years agolast modified: 9 years agoBongo
8 years ago
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