Attic Spray Foam Insulation St. Louis, MO 63101 | St Louis Spray Foam Insulation

Spray Foam Insulation in St. Louis, MO (63101) · Local Professionals

St Louis Spray Foam Insulation · Fast response in St. Louis and the St. Louis area · Free estimate 24h

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St. Louis runs on red brick, fieldstone basements, and attics that bake at 130 to 150 degrees in July and drop into the teens by January. Whether you own a 1920s brick bungalow in St. Louis Hills, a 1880s flat in Lafayette Square, or a ranch in Kirkwood, your attic and rim joists are the two places where heat and cold leak fastest, and where moisture condenses when the humidity flips with the seasons.

St. Louis Spray Foam Insulation has been serving St. Louis and the surrounding area since 2012. We spray foam attics, crawl spaces, rim joists, and closed walls in the neighborhoods and suburbs where the building stock demands it. Our team shows up with a written estimate that names the R-value and thickness you are getting, mechanical ventilation during the cure, and a phone number that works when you call back with a question.

Spray Foam Insulation in St. Louis (63101)

The insulation challenge in St. Louis is shaped by three facts. First, almost every house sits on a basement, crawl space, or slab, and the rim joist where the band board meets the foundation is almost always open to the outside air or packed with fiberglass that has settled and lost contact with the wood. Second, attics in St. Louis bungalows and brick flats have knee walls, finished half-stories, and tight rafter bays that blown-in insulation cannot reach without cutting into drywall. Third, the mixed-humid climate means moisture drives outward through cold winters and inward through hot, wet summers, so every assembly has to handle both directions without trapping water inside the wall or attic.

Closed cell spray foam seals rim joists tight and stops air leakage at the foundation. Open cell foam fills attic bays and knee walls without crushing, and lets walls breathe if moisture does get in. Wall injection foam reaches the cavities inside closed brick walls that have sat empty since 1920. We remove old, compressed, or damp insulation before any new foam goes in. Our crews are fully insured, and we have been doing this work in St. Louis neighborhoods for over a decade.

Our services in St. Louis

Attic Spray Foam Insulation in St. Louis · Open-cell roof-deck foam turns an attic that bakes at 140°F in July and freezes…
Closed Cell Spray Foam Insulation in St. Louis · Two-pound closed-cell foam delivers R-6.5 per inch with its own vapor retarder…
Open Cell Spray Foam Insulation in St. Louis · Half-pound open-cell foam air-seals attics and walls at a friendlier price per…
Wall & Injection Foam Insulation in St. Louis · Injection foam fills closed frame walls through small drilled ports…
Crawl Space Spray Foam Insulation in St. Louis · Closed-cell foam on crawl space walls and subfloors ends the cold floors of…
Rim Joist & Band Joist Spray Foam in St. Louis · Basement rim joists leak more cold air than almost anything in a St. Louis…
Garage Spray Foam Insulation in St. Louis · Garage ceilings under bonus rooms and walls shared with the house are…
Metal Building & Barndominium Spray Foam in St. Louis · Closed-cell foam stops a Missouri metal building from sweating in spring and…
Commercial & New Construction Spray Foam in St. Louis · Warehouses; offices; churches and production builders served on schedule.
Insulation Removal in St. Louis · Old blown-in and batts vacuumed out before any new foam goes in, never buried.
Insulation Replacement & Re-Insulation in St. Louis · The full reset: old material removed; gaps air-sealed…
Air Sealing in St. Louis · Top plates; can lights; chimney chases and attic hatches leak more heated and…

How a Job Works in St. Louis

We start with a free on-site assessment. You walk us through the problem: a room that never heats or cools, a utility bill that has climbed, condensation on attic sheathing in winter, or an attic that is simply too hot in summer. We measure the space, look at what is already there, check for moisture or damp insulation, and explain what has to happen first. If old insulation is wet, compressed, or contaminated, we remove it before any foam goes in. We do not spray over a wet substrate, period.

On the work day, we set up mechanical ventilation in the attic or crawl space and spray the foam in controlled passes, hitting the manufacturer's ratio and drum temperature. The foam cures while fresh air moves through the space. You can re-enter the attic or crawl space after twenty-four to forty-eight hours, depending on the temperature and humidity. We clean up the workspace, haul away packaging, and walk through the finished job with you.

Attic spray foam in St. Louis typically runs from $1.50 per square foot for open cell, depending on depth and R-value. A 1,500-square-foot attic with eight inches of open cell foam costs roughly $1,800 to $2,400 before any removal. Rim joist and band joist sealing starts at $650 and scales with the perimeter and height of the band board. Crawl space foam starts at $2,500 and depends on the square footage and whether the space is vented or conditioned. Wall injection foam for a closed brick wall runs from $2 per square foot. If old insulation has to come out first, add $950 to $1,500. The biggest cost factors are the area to cover, the R-value and thickness you need, whether you choose open or closed cell, and what has to be removed or fixed before we spray. Call us at (314) 912-1801 for a free written estimate with R-value and thickness spelled out.

✅ Written Estimates with R-Value & Thickness Specs, fully insured for work in St. Louis and nearby areas.

I have a 1920s brick bungalow in St. Louis Hills with a half-story attic and knee walls. The bedroom up there is freezing in winter and hot in summer. What is the best fix?

Knee walls and finished half-story attics are common in St. Louis bungalows, and blown-in insulation cannot reach the rafter bays or pack tight against the sloped ceiling. Open cell spray foam fills those tight spaces, seals air leaks around the collar ties and at the top plate, and lets you use the whole room. We also seal the rim joist at the foundation where the band board meets the basement, which stops cold air from rising through the floor. A typical half-story attic runs $1,800 to $3,200 depending on the square footage and R-value target.

My attic has wet insulation and a smell that comes down into the house. What happens before you spray?

Damp or moldy insulation has to come out completely before any foam goes in. We remove the old insulation, haul it away, and let the attic dry out. If there is standing water or an active leak, that has to be fixed first, or we walk away. Once the attic is dry and the source of moisture is stopped, we spray the foam. The smell usually comes from the old insulation decomposing or from mold growth in the fiberglass. Once we remove it and seal the attic, the smell stops. Call (314) 912-1801 and describe what you see and smell, and we will tell you what comes first.

How much does it cost to remove old insulation and spray foam in an attic in St. Louis?

Removal runs from $950 to $1,500 depending on how much is there and how it is packed. Once it is out, open cell foam starts at $1.50 per square foot. For a 1,500-square-foot attic with six inches of open cell (R-19), figure $950 for removal and $2,250 for foam, total $3,200. Closed cell is denser and more expensive but stops moisture and air better. Get a free estimate that breaks down removal, foam type, thickness, and R-value at (314) 912-1801.

Who checks the R-value and makes sure the foam is thick enough to meet code in St. Louis?

The energy code and building code that apply at your address are set by Missouri state law and enforced by the building official in your city or county. Attic ventilation, ignition barriers, and thermal barriers are all governed by code. The fifteen-minute thermal barrier is the one most installers get wrong: if your attic is not conditioned (not heated or cooled), spray foam has to be covered with a thermal barrier rated to hold back flame for fifteen minutes. If the attic is conditioned, the barrier rules change. Our written estimate names the R-value and thickness we are installing. The building department inspects and approves the final work. Check the City of St. Louis website or your county building office to confirm what applies at your address.

Can we stay in the house while you spray foam in the attic?

Yes. We run mechanical ventilation during the cure to pull fumes out of the attic and out of the house. You and your family can stay downstairs. The attic and any rooms directly below it should not be used for twenty-four to forty-eight hours after we finish, depending on the outside temperature and humidity. Open the windows if the smell lingers. By the second day, the foam is fully cured and the smell is mostly gone. If you have an HOA and the work is visible from the street (metal building or exterior wall foam), let us know and we will coordinate with the architectural committee.

Are you insured if something goes wrong during the spray foam job?

Yes. We are fully insured with general liability and workers' compensation. Our crews carry the coverage that protects your property and our team if an accident happens on the job. When you call for an estimate, ask us to confirm our insurance and we will provide the details.

July and August in St. Louis are brutal. Is that the best time to spray foam an attic?

July and August are actually the worst time. Attic temperatures hit 130 to 150 degrees, and the foam cures faster in the heat, which can cause uneven coverage and voids. Spring (April to May) and fall (September to October) are ideal: the attic is cooler, the cure is more controlled, and the weather is stable. Winter is possible but slower. If your attic is unbearably hot right now, we can schedule for late September or October when the heat breaks. A cooling bill spike in July is a sign that the attic insulation is failing, and that is worth fixing before next summer. Call (314) 912-1801 to talk about timing.