How Waterproofing Your Basement Can Boost Your Home's Value Closedcell spray foam is the best way to insulate concrete basement walls. This is because it can achieve a higher Rvalue, along with excellent moisture resistance, with less thickness required. It can fill in all the gaps and spaces thoroughly, giving you the best protection against moisture and air infiltration. If your exterior walls are constructed from 2by4 inch studs, the most insulation that can go into the wall while retaining its Rvalue is R13 or R15 as these are both made to fit a cavity 3 12 inches deep. Insulation level are specified by RValue. RValue is a measure of insulations ability to resist heat traveling through it. The higher the RValue the better the thermal performance of the insulation. The table below shows what levels of insulation are costeffective for. Should I use the same Rvalue of insulation throughout my home? It's more efficient to use insulation with higher Rvalues in the attic and in rooms with cathedral ceilings than in wood frame walls, basements, or crawl spaces with walls. Insulate the floor from below, and be sure to insulate any water pipes or heatingcooling ducts in the crawlspace, especially any water pipes at or near the perimeter. Unvented crawlspaces can be treated like an unintentionally heated basement, by insulating the exterior foundation walls. Look at the first number under BASEMENT WALL RVALUE. That's the minimum Rvalue you need to be safe. Divide that number by the perinch Rvalue of the foam you want. For example, if you live in zone 4, it says you need a minimum of R10 on the walls. An Rvalue is a number that tells you how good a material is at resisting the flow of heat. If it resists the flow of heat well (has a high rvalue) then it's a good insulating material. For the purposes of insulating Warmer climates only require an R38 or higher, or about 12 or more. Wall Insulation: While wall insulation is limited by the width of the studs, different materials provide higher or lower Rvalues. Fiberglass batts for standard 24 walls are now available in low, medium, and high density products that range from R11 to R15. Rvalues provide the optimal level for energy savings and comfort. They may not be reachable in all existing homes, but homeowners should come as close as possible for the optimal effect. Your Homes Insulation Basement Wall: R13 MD ID NM TX OK KS NE SD. Mar 04, 2015I just watched a mike Holmes episode. He was building out a basement for bar, home theater, gym, etc. against all the walls he used roxul board as an insulation barrier then the walls were framed. I've read where Martin Holliday advised against this practice. It makes more sense to use foam or foam board as it won't hold water. Generally, zones 1 and 2 cover the southern states, which suggest no necessary values to R10 for basement walls. Zones 3 and 4 include the Midwest and Northern regions, requiring R10 to R19 values. Extremely northern regions and high elevations are zone 5, requiring R15 to R19 values. Advanced Frame Wall Construction Building Science Corp How to Insulate a Basement Wall. What R Rating Should You Put in a Basement? It's up to you to decide the Rvalue of your insulation. In Climate 4C, the 2012 IRC requires a minimum of R15 for basement walls (assuming that we are talking about continuous rigid foam or spray foam insulation the best approach). That's a minimum Rvalue; you can install more insulation than that if you want to.