Jan 7, 2014 · Expanded polystyrene has an R-value of about R-4 per inch, so that R-30 ICFs would need to have two layers of 4-inch thick foam, one on each side of the concrete. If the ICFs are that thick, that's great. Some ICF manufacturers have been known to exaggerate, and report "equivalent R-values" -- a meaningless term.

Oct 3, 2011 · Thermal mass vs. higher R-value. With a core of concrete, the ICF wall has more mass than a wood-framed wall, and Mike Collignon thinks this benefit is worth considering. “This often doesn’t show up in R-value discussions,” he writes, “but it [is] quantifiable and does make a difference in reducing air infiltration.”

Oct 15, 2024 · It is the real time difference between the building interior temp and the thermal mass temp (i.e., NOT the outdoor temp) that then determines the interior building heat transfer rate and hence the real time effective R-value for ICF. Other key points to ICF: Fire protection rating of 2-4 hours No air infiltration through a solid ICF wall

Mar 27, 2024 · We specify a standard R-22 ICF, but a higher R-value ICF could be used without having to change the overall assembly details. We call for the inner layer of the ICF insulation to be cut down 4 in. (pictured left), allowing the slab to extend over the core to provide a flat working surface for wall framing, and to make the continuity of the air ...

Sep 11, 2022 · At the end of the day, your true R value is what the foam is, R22 in most cases. The numbers that ICF manufacturers like to brag are from when the outdoor temperature crosses the indoor temperature within the 24 hour window. Your thermal mass modified R value in the summer could be very high if you get 60* nights and 90* days.

Jul 6, 2021 · Newly completed tests at Oak Ridge National Laboratory (ORNL) find that the static, clear-wall R-value of a 10-inch Rastra wall is R-7.6. Using dynamic benefit multipliers ranging from 1.79 to 2.17 would yield dynamic R-value equivalents …

Sep 19, 2020 · An R value of 1.75 per inch is what Martin Holliday quoted from Nexcem's own literature. The maximum R value of 24.5 would occur at that point in the cross section of the block (the ends) where you have a full 14 " thickness of nothing but the block form R 1.75 material from inside to outside (i.e. where there is no concrete or rock wool in the ...

Jul 5, 2020 · >"Planning on R-23 over the roof deck and R-15 in the rafter cavities." Explain that a bit. Code min on an R-value basis is R49- you're at only R38 center cavity, though it probably just squeaks by code minimum performance on a U-factor basis with a tiny bit of marging if the R23 is continuous, not thermally bridged by framing.

Nov 24, 2009 · Not holding R-value constant would have made this report confusing at best. A 2x8" foam wall system, or a CIC requiring 5 plus inches of internal foam to get to the typical ICF R-value --- or an Interior Mass system that utilizing the same exterior foam content and the same thermal mass of 6 inches of concrete --- each of these (better than ICF ...

Jun 20, 2018 · Remember, ICF is basically poured in place concrete with the forms remaining in place after the pour. In addition, CMU with foamboard doesn't have the same R-Value as ICF with 2.5" on both sides. ICF like Nudura is ready for interior drywall with plastic studs every 8 inch OC and the exterior is ready for stucco.