Frequently Asked Questions

The Twin Cities counties are in Climate Zone 6 of Minnesota's energy code. The efficientwindows.org summary of the 2012 IECC-based code lists R-20 plus R-5 continuous insulation, or R-13 plus R-10, for wood-frame walls in Zone 6. That applies to new construction and permitted work; filling the walls of an existing house is judged by what the cavities can hold, and Xcel's wall rebate asks for R-11 or better in a previously empty cavity.

National guides put installed spray foam at about $1.50 to $5.00 per square foot, with closed cell costing more than open cell (HomeGuide). Rim joists commonly run $2,000 to $2,500 and whole-house projects $8,000 to $20,000 by the same guide. We price your house after measuring it, and the written estimate is what you pay.

Not by itself. Some buyers and appraisers worry about foam sprayed on the underside of a roof deck because it can hide roof leaks, and a few lenders ask questions about it. Foam that is installed for a clear reason, with the product and location documented, is easy to explain at sale time. We give you that paperwork.

The concerns usually come from bad installs: foam mixed or sprayed wrong that smells, pulls away from framing or hides wet wood. Others come from foam on roof decks that makes roof inspections harder. Proper mixing, the right thickness per pass, ventilation during curing and a moisture check before spraying are what prevent those problems.

It depends on the spot. Closed cell is the usual pick against cold concrete, on rim joists and in shallow rafters because it resists moisture and packs more R-value per inch. Open cell costs less per inch and works well inside walls and some attics when paired with a vapor control plan. Many houses get some of each.

Spray foam is a two-part product made by a number of chemical manufacturers and sold to installers as matched A and B components. What matters to you is that the product suits the surface, is installed at the maker's rated thickness per pass, and is named on your quote. We tell you exactly which product we plan to use.

Usually, yes. Closed wall cavities are most often filled with dense-pack cellulose or fiberglass blown through small holes from outside or inside, then patched. We check for knob-and-tube wiring and blocked bays first, since both change the plan.

HomeGuide's guide says to plan on leaving for 24 hours or more, and the foam maker's instructions set the exact re-entry time. We ventilate the work area during and after spraying and tell you the time before the job starts.

Closed cell. It sits against the coldest part of the house, and closed cell's vapor resistance keeps warm indoor air from condensing on the wood behind it. Open cell is not a good fit there.

No. Foam has to bond to the framing or sheathing. Old batts get pulled out first, which is part of the prep on the quote.

It helps when the cause is warm air leaking into the attic or a poorly insulated roofline. Ice dams also depend on ventilation and snow, so we look at the whole attic before promising a fix.

Properly mixed foam should not keep smelling once it has cured and the area has been ventilated. A lasting odor usually points to an installation problem, which is why mixing and pass thickness matter.

The efficientwindows.org summary of Minnesota's energy code lists R-49 for ceilings in Climate Zone 6, which covers the Twin Cities counties. That applies to new work. For an existing attic, DOE suggests R-49 to R-60, and Xcel's rebate asks for R-49 or more.

Only if warm air leaks are sealed too. Most ice dams on older St. Paul houses come from heat escaping around chimneys, kneewalls and light fixtures, so we seal those first.

Yes. The flat attic above the ceiling, the kneewall spaces and the sloped ceilings are handled separately, often with foam on the slopes and loose fill above.

Not if it is dry and clean. New fill can go on top after sealing. Wet, moldy or rodent-soiled insulation should come out first.

Yes. Dense-pack fill goes in through small holes from the outside or inside, and the holes are patched afterward.

Live knob-and-tube should not be covered with insulation. An electrician needs to evaluate or replace it before we fill those walls.

Not when installed at proper density. Dense-pack is blown tight so the cavity stays full; loose fill at low density is what settles.

In closed walls, injected fill usually costs less and works well. Spray foam is mainly for open walls during a remodel, where it can also seal and add R-value per inch.

Yes. It is the easiest time to reach the whole band and the walls, and it avoids tearing out new drywall later.

We usually remove them. Batts let moist air reach the cold rim, where it can condense. Closed-cell foam directly on the wood is the better fix.

No. Foam is not a waterproofing product. Water coming through the wall needs to be handled outside first.

In most cases yes. Foam in occupied spaces usually needs a thermal barrier such as drywall, and we note what applies on your quote.

For R-49, roughly 13 to 18 inches depending on the product and its rated R-value per inch. The bag label lists the depth and coverage for each R-value.

Both work. Cellulose gives more R per inch and slows air slightly better; fiberglass is lighter. We recommend based on your attic and ceiling.

Yes, if the old material is dry and clean and the attic floor has been sealed.

Loose fill settles a little over time, which product specs account for. We blow to the settled depth on the label.

Wet, moldy, rodent-soiled or smoke-damaged insulation should come out. Dry, clean insulation can usually stay, with new material added on top after sealing.

Most is not. Vermiculite may contain asbestos and should be tested before anyone disturbs it.

A typical attic takes about a day to remove, and replacement often follows the same or next day, depending on size.

Yes, by cutting and scraping. It costs more than removing loose fill, and we explain why it needs to come out first.