Walls

Walls Cavity Insulation in Framed Walls: Batts, Blown, and Dense-Pack R-valueR-13 to R-15 for 2x4 walls; R-19 to R-21 for 2x6 walls; dense-pack and blown-in can achieve similar or slightly higher values depending on density and cavity depth. Target R-value should match climate and code, often R-20+ for cold climates. CostTypical installed cost ranges from about $1.50 to $4.50 per square foot of wall area, depending on material, cavity depth, access, and labor. Dense-pack and blown-in tend to be at the higher end; batts at the lower end for simple, open cavities. SavingsHeating and cooling demand can drop by roughly 10% to 30% when upgrading an uninsulated or poorly insulated wall, but actual savings depend on climate, air sealing, existing insulation, and house tightness. Savings are often modest if air leakage and other envelope gaps remain. AccessBatts in open cavities are a careful DIY possibility; blown-in and dense-pack almost always require a crew and specialized equipment. Retrofits into closed cavities are best left to professionals. Cavity insulation in framed walls is one of the most direct ways to slow heat movement through the largest above-grade surface of many homes. Walls Continuous Exterior Insulation and the Thermal Bridge Problem R-valueR-5 to R-20 continuous, depending on climate zone and wall assembly Cost$2 to $6 per square foot installed for rigid foam or mineral wool, plus detailing SavingsTypically 10 to 25 percent of wall-related heating and cooling demand, with diminishing returns at higher R-values AccessCrew needed for most installations; a careful homeowner can handle small retrofits or detailing with proper guidance Heat does not respect the tidy lines we draw on building plans. Walls Insulating Solid Masonry Walls Without Trapping Moisture R-valueR-5 to R-15 for most residential retrofits; continuous rigid or mineral insulation in the R-5 to R-10 range is common, while thicker interior furring with batt or blown fill can reach R-13 to R-15 where space and drying allow CostRoughly $3 to $12 per square foot installed for interior furring and insulation, and $8 to $25 per square foot for exterior rigid insulation with new cladding and trim; whole-wall projects commonly land in the low thousands to low tens of thousands depending on size, access, and finish work SavingsTypically a modest reduction in heating demand, often in the range of 5 to 20 percent of wall-related losses, with smaller cooling effects; results depend heavily on air sealing, window and roof conditions, and how much of the wall was previously uninsulated AccessA careful homeowner can handle small interior jobs such as sealing penetrations, installing rigid board on a furred wall, or adding a vapor-permeable insulation layer, but exterior retrofits, structural furring, flashing, and any work involving masonry repair or drainage details generally call for an experienced crew Solid masonry walls are common in older homes, and they behave very differently from modern framed walls. Walls Rim Joists and Sill Plates: The Overlooked Band of Loss R-valueR-10 to R-20 in most climate zones, with colder zones targeting the upper end of that range when rigid foam or closed-cell foam is used CostRoughly a few hundred to a couple thousand dollars for a typical basement or crawlspace perimeter, depending on length, access, and material choice SavingsOften a modest but noticeable reduction in heating demand, with smaller cooling effects in humid climates; results vary widely with existing leakage and climate AccessA careful homeowner can handle exposed, dry, accessible rim areas with rigid foam and sealant; a crew is needed for closed-cell spray foam, tight crawlspaces, or any area with moisture problems Most insulation conversations start at the attic and stop at the basement stairs.