Average Wall Insulation Costs
The average cost of adding wall insulation ranges from $1 to $4 per square foot, depending on the insulation type and whether the installation involves new construction or retrofit. For a typical home in Franklin, TN, insulating exterior walls costs between $2,000 and $8,000 total.
Retrofit wall insulation — adding insulation to existing walls — is generally more expensive than insulating during new construction because it requires accessing wall cavities through existing surfaces. Injection foam and dense-pack cellulose are popular retrofit options, while spray foam is ideal for open-wall applications during renovations.
Material Options and Costs
Several insulation materials work well for wall applications. Spray foam insulation offers the best performance at $1.50-$3.50 per square foot, providing both thermal insulation and air sealing. Fiberglass batts are the most affordable at $0.50-$1.50 per square foot but offer lower performance. Injection foam is designed specifically for retrofit applications at $1.50-$2.50 per square foot.
For homes in the Franklin area, the choice often comes down to whether the walls are open (during renovation) or closed (retrofit). Open walls are best insulated with spray foam for maximum performance, while closed walls may require injection foam or dense-pack cellulose blown through small access holes.
Is Wall Insulation Worth the Cost?
Adding wall insulation is one of the most impactful energy upgrades you can make. Walls account for approximately 35% of a home's total heat loss, making them a significant source of energy waste when poorly insulated. Properly insulated walls reduce energy costs, eliminate drafts, and improve comfort throughout the home.
The investment typically pays for itself within 4-7 years through lower energy bills. For Franklin homeowners planning to stay in their homes long-term, the comfort and efficiency improvements make wall insulation an excellent investment. Contact BST Spray Foam of Franklin at 629-245-2588 for a free estimate.