Frequently Asked Questions

Yes, when the walls are open during a remodel. Foam fills the stud bays and seals them in one step. For closed plaster walls, dense-pack cellulose blown through small holes is usually the more practical choice.

Closed-cell foam, at about R-5 to R-7 per inch according to HomeGuide, compared with R-3.5 to R-3.7 for open-cell. That matters in shallow rafters and rim joists. On an open attic floor, loose fill reaches R-60 for less.

HomeGuide's 2026 range is $1.50 to $5.00 per square foot installed; Fixr lists $3.15 to $7.50 for existing walls. Access and building type change the total in Boston. Your written estimate is the price.

It is a two-part polyurethane product. The two liquids mix at the spray gun, react, and expand into foam that bonds to the surface. Open-cell and closed-cell versions differ in density, R-value per inch and how they handle vapor.

Mass Save lists 75 to 100 percent off approved insulation improvements after its no-cost assessment, and those incentives apply to work approved through the program. Start with the assessment; for work outside it, we price directly.

Yes, but the building works as a whole. Air entering at the basement exits through the top floor. We will tell you what each floor needs, even if you start with one.

Closed-cell. It slows vapor and resists water, so it keeps humid basement air off cold brick, stone and wood.

Often, if the cavity can be reached. Closed-cell foam under the deck seals and insulates where there is little depth. We look at the roof structure first.

In living spaces and many basements it needs a thermal barrier like drywall, unless a product rated for exposure is used. We explain what applies before you sign.

After curing and ventilation, the space is reoccupied; HomeGuide's guidance is to stay out at least 24 hours. We tell you exactly when to come back.

Usually you can insulate inside your unit, but the roof, basement and exterior walls may be common areas. Check your condo documents and association first.

Usually not. Dense-pack and attic work can happen while people live there, with some rooms off-limits during the day. Foam inside a unit needs it empty for about 24 hours.

Often the basement rim and the roof, because they cut the air flow through the whole building. Walls can follow floor by floor.

Sealing and insulating the attic floor removes most of the heat that melts roof snow. Ventilation and roof shape matter too, and we check both.

Yes, usually by spraying foam in the rafters from the side attics, or by dense-packing closed rafter bays. We look at access first.

The Massachusetts stretch code summary lists R-60 for new ceilings. With cellulose that is roughly 16 to 17 inches, and we leave depth markers so you can check.

Dense-pack is blown at high density specifically so it does not settle in the bay.

Outside avoids interior patching; inside avoids disturbing siding. It depends on your siding and plaster. We recommend one after looking.

If the system is inactive, yes. If it is live, an electrician needs to address it first.

Yes, for most older homes. It is a small job that cuts drafts around the entire house.

Sometimes, but damp stone may need to dry. We often foam the rim only and recommend drainage fixes first.

No. It stops air and slows vapor. Water entry needs drainage work.

No. Dry, clean insulation can stay. Removal makes sense when it is wet, moldy, soiled or blocking air sealing.

Light, pebbly granules, gray-brown or gold. Leave it alone and get it tested.

Many attics are cleared in a day. Tight triple-decker access or heavy contamination can add time.