Frequently Asked Questions

Closed-cell foam, at about R-5 to R-7 per inch according to HomeGuide, compared with roughly R-3.5 to R-3.7 for open-cell. That is why closed-cell goes in tight spots like rim joists, 2x4 walls and shallow roof bays.

The floor is about 400 square feet, but you insulate the walls and ceiling, which can add up to 1,000 square feet or more of surface. At HomeGuide's $1.50 to $5.00 per square foot, that is roughly $1,500 to $5,000, and small jobs often hit a minimum charge. We measure and give you a written price.

Two-part foam kits are sold for small areas, and canned foam works for sealing small gaps. Larger jobs need the right mix temperature, thickness per pass and ventilation, and mistakes are hard to undo because cured foam must be cut or scraped off. For a rim joist or a whole attic, a professional install is usually the safer choice.

Iowa's code table lists R-49 for ceilings in Climate Zone 5, which includes Polk, Dallas and Warren counties. Existing homes are not required to meet it, but it is a sensible target, and most older attics we see are well below it.

Yes in heated basements and living spaces. Cold attics, garages and pole buildings need the surface and the foam within the maker's temperature range, so we add heat or schedule a milder day.

Not always. If the attic is vented and the floor is open, sealing the gaps and blowing loose fill to R-49 usually costs less. Foaming the roof deck makes sense when the attic holds ducts or equipment, or when there is no room to vent a vaulted ceiling.

Closed-cell, at about R-5 to R-7 per inch according to HomeGuide, compared with R-3.5 to R-3.7 for open-cell.

It costs more per square foot, it is hard to remove later, and it must be installed and cured carefully. On an open attic floor it is usually more than the job needs.

Closed-cell slows vapor and keeps humid indoor air off cold surfaces where it would condense. It is not waterproofing, so leaks are fixed first.

Several chemical companies make two-part spray foam systems for contractors. What matters more for you is that the product suits the spot, is applied at the right thickness and temperature, and is allowed to cure fully.

Iowa's code table lists R-49 for Zone 5 ceilings. For blown cellulose or fiberglass that typically means well over a foot of depth, depending on the product.

It helps, but air sealing matters more. Ice dams start when warm air leaks into the attic and melts roof snow, so we seal first and keep the eaves vented.

Only if it is wet, moldy, contaminated by animals, or blocking air sealing. Dry, clean insulation can usually stay and be topped up.

Most single-family attics take a day. Older houses with a lot of sealing or removal can take longer.

Often yes. It is a small area, but it leaks air around the entire house, and HomeGuide puts a typical rim joist job at about $2,000 to $2,500.

Once it is dry and the source of water is fixed, yes. Closed-cell foam is the safer choice because it does not absorb water.

In living space, foam plastic generally needs a thermal barrier such as drywall. Some exposed areas can use an approved coating instead. We explain the options for your space.

Iowa's code table lists R-15 continuous or R-19 cavity for basement walls in Zone 5. About three inches of closed-cell foam reaches the low end of that.

Yes. Dense-pack cellulose or fiberglass is blown through small holes, then the holes are plugged and patched.

Usually not. Expanding foam in closed walls can leave voids and put pressure on plaster or drywall. Dense-pack is the standard method.

Iowa's code table lists R-20, or R-13 plus R-5 continuous, for wood-frame walls in Zone 5.

After the rough electrical, plumbing and framing inspections and before drywall.

For stopping condensation in cold storage, about an inch of closed-cell is common. For a heated shop, more on the roof and walls makes sense. We size it to how you use the building.

Usually not. Foam needs to bond to a clean surface, so loose or damaged blankets typically come down first.

Closed-cell foam bonded to the steel keeps warm, damp air off the cold panels, which is what causes the drip.

Yes, with foam or insulated panels, though weatherstripping around it matters too.

If it is wet, moldy, soiled by animals, crushed flat or full of debris, removal is usually worth it. If it is dry and clean, topping up is usually fine.

Vacuum removal runs hoses from the attic to bags or a truck, so the dust stays contained. We protect the path through the house.

Not until it is tested. If it contains asbestos, a licensed abatement contractor must remove it first.

Yes. It must be cut or scraped off by hand, and HomeAdvisor notes foam is pricier to remove than other types.