What is spray foam and how does it work?
Spray foam is two liquid chemicals that get mixed at the tip of a spray gun. When they combine, they expand into a solid foam that sticks directly to whatever surface it touches — wood, metal, concrete. That bond is what makes spray foam different from other insulation. It does not just sit between the studs. It seals to the framing and sheathing, filling every gap, crack, and odd shape in the wall or roof.
That seal is a big deal in South Alabama. Our summers push attic temperatures past 140°F, and the humidity stays above 60% for months. Regular insulation slows heat, but air still moves around it. Spray foam stops that airflow, which is why most people notice a real difference in comfort and power bills after it goes in.
What is the difference between open-cell and closed-cell?
There are two types of spray foam, and they do different things.
Open-cell (sometimes called half-pound foam) is the lighter, softer option. It expands a lot — about 3 inches per pass — and lands around R-3.7 per inch. The tiny cells in the foam are not completely sealed shut, so moisture vapor can pass through it slowly. That is actually useful on roof decks — if you ever get a small roof leak, the water comes through and you can spot it before it rots the wood underneath.
We use open-cell most often for:
- Roof decks and vaulted ceilings where we need to fill the full rafter space
- Interior walls where cutting down noise matters
- Big open attics where keeping material cost reasonable is part of the plan
Closed-cell (two-pound foam) is denser and stronger. It gives you about R-6.5 per inch — almost twice the R-value of open-cell in the same thickness. The cells are completely sealed, so the foam itself blocks moisture. At 2 inches thick, it acts as its own vapor barrier. It also adds structural strength to walls, which matters in metal buildings and older wood-frame construction.
We use closed-cell most often for:
- Band joists and rim joists where moisture is pushing through from outside
- Metal buildings where condensation on the walls and ceiling is a problem
- Tight spaces where you need the highest R-value in the least amount of depth
- Anywhere the foam might get wet or be exposed to weather
We do not push one type over the other. Which one makes sense depends on where it is going, how moisture moves through the building, and what fits the budget.
What do we look at before giving you a price?
Every spray foam job starts with a site visit. We walk the space and check:
- What is already in there — Old fiberglass that needs to come out? A vapor barrier in the wrong spot? Signs of past water damage or mold?
- How deep the cavities are — We measure the rafters or studs to figure out how much foam the space can hold, and check for wiring, plumbing, or ductwork that we need to work around.
- Moisture and airflow — Is the attic vented or sealed? Where is moisture likely to collect inside the walls or roof? Any signs of condensation?
- Heating and cooling equipment — Are the ducts and air handler inside the insulated space or outside it? Bringing them inside is one of the biggest efficiency gains spray foam makes possible.
- Budget and priorities — Sometimes the smartest move is spray foam on the roof deck and blow-in on the attic floor. We will tell you when a mixed approach saves money without giving up performance.
Every quote is based on what we actually see on site, and we leave the workspace clean when we are done.