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5 Causes of Heat Gain in Houston Homes — and How to Fix Them
Houston runs air conditioning for 9–10 months of the year. If your energy bills are higher than they should be, or if your home is uncomfortable despite constant AC, there are five specific heat gain pathways responsible — and spray foam addresses all of them.
Radiant Heat Through the Roof Deck
In Houston, roof surface temperatures can exceed 170°F on a clear summer day. The roofing material absorbs solar energy and radiates it downward into the attic space. An uninsulated or under-insulated attic can reach 160°F+ — and that heat load radiates downward through the ceiling into the living space below. Your air conditioning system is constantly fighting this radiant load from above. The solution is spray foam applied at the roof deck (underside of the roof sheathing) rather than on the attic floor. This converts the attic to a conditioned or semi-conditioned space, keeping the HVAC ducts in a controlled environment and dramatically reducing the radiant load on the ceiling assembly.
Conduction Through Poorly Insulated Walls
Every exterior wall in your home is a thermal conductor. Heat moves through the wall assembly from hot outside to cool inside — through the siding, through the air gap, through the sheathing, through the insulation (or lack of it), and into the interior. In Houston's 95°F+ summer afternoons, a south- or west-facing wall with inadequate insulation is a continuous heat source for the room it bounds. Spray foam in exterior walls — particularly on south and west exposures — dramatically reduces this conductive heat gain. At R-6.5 per inch, closed-cell foam in a 2×4 wall cavity delivers R-26, roughly double the performance of fiberglass batts in the same space.
Air Infiltration Through Gaps and Penetrations
This is often the largest single contributor to heat gain in Houston homes — and the hardest to see. Hot, humid outdoor air enters the building through every unsealed gap: around electrical outlets on exterior walls, at top plates where walls meet the ceiling, around plumbing and wiring penetrations, at the attic hatch, around can lights, and through the countless cracks that develop as a house ages and settles. The DOE estimates that air infiltration accounts for 25–40% of home energy loss. In Houston's humid climate, this infiltrating air also brings moisture — contributing to humidity problems, condensation on AC components, and mold risk. Spray foam seals all of these pathways simultaneously in a way that caulk and weatherstripping cannot.
Heat Through Ductwork in Unconditioned Attics
Most Houston homes have HVAC ductwork installed in the attic. When the attic reaches 160°F in summer and your ducts are carrying 55°F supply air, the ducts lose heat to the surrounding attic air through every foot of duct run — even with standard R-8 duct insulation. Studies show that ductwork in unconditioned attics can lose 20–30% of the HVAC system's output before it reaches the living space. Converting the attic to a conditioned or semi-conditioned space with spray foam applied at the roof deck puts the ducts in a controlled environment, dramatically improving HVAC system efficiency.
Heat Through Uninsulated Floors
This applies primarily to homes with crawl spaces, pier-and-beam foundations, or any raised floor assembly. In Houston's summer, the air under the floor can reach extreme temperatures as it's trapped and heated by the surrounding soil and the radiant heat from the building's exterior. Without insulation between this hot air mass and the living space above, heat conducts through the floor assembly continuously. Spray foam applied to the underside of the floor framing (or at the crawl space walls to convert it to a conditioned crawl) blocks this heat transfer path and also stops the moisture and pest infiltration that uninsulated crawl spaces invite.
What a Comprehensive Spray Foam Upgrade Looks Like
The highest-impact project for most Houston homeowners is attic spray foam at the roof deck. This single installation addresses heat gain pathways 1, 4, and partially 3 simultaneously — and typically delivers the fastest return on investment.
For maximum energy performance, we combine attic roof deck foam with air sealing at the top plates and penetrations, wall insulation if accessible, and crawl space treatment if applicable. We assess each home individually and recommend the combination that delivers the best return for your specific building and budget.
Most Houston homeowners see their energy bills drop $100–$200 per month after attic spray foam installation. The full installation cost is typically recovered within 3–5 years through energy savings alone.