Yes. Injection foam is pumped into your closed wall cavities through small access holes, and the holes are patched when the crew is done. There is no drywall demolition and no remodel. It is the standard way to insulate finished walls in an existing home, which is why it suits older Spokane and Coeur d'Alene houses so well.
The short answer
Most homeowners assume that insulating exterior walls means opening them up: pulling drywall, living in dust for a week, then paying to put the room back together. That assumption is why a lot of Inland Northwest houses still have empty walls decades after everything else got updated.
It is also wrong. Injection foam was built for exactly this problem. The wall stays closed, the finished surfaces stay where they are, and the insulation goes in through holes roughly the size of a quarter.
Why older walls are empty in the first place
Houses built in Spokane and Coeur d'Alene before about 1980 often went up with little or no wall insulation, because the energy codes that require it either did not exist yet or asked for very little. The framing, the sheathing, and the siding all went on as normal, and the cavity between the studs was simply left as air.
An empty wall cavity is not a still, insulating pocket of air. Air moves inside it, carrying heat out in winter and in during summer, which is why an uninsulated wall can feel cold to the touch on a January morning even when the furnace is keeping up.
How injection foam actually gets into a finished wall
The process is straightforward, and on most homes it is a one-day job.
- We find the cavities. Every stud bay gets treated individually, so the crew maps the framing and identifies obstructions like fire blocking, plumbing, and old wiring runs.
- We open small access holes. Usually from the outside, one or two per stud bay depending on wall height. On brick or certain interior-access situations the approach changes, but the holes are always small and always planned.
- The foam goes in. It is injected as a liquid that expands to fill the cavity, working its way around wiring and into the gaps a batt could never reach. It cures in place.
- We close everything up. Holes are plugged and the siding is put back. On vinyl and aluminum siding the courses come off and go back on, so there is nothing to see afterward.
Nobody moves out. No room gets gutted. The interior of your house is largely untouched, which is the entire point.
Where the access holes go, by siding type
The siding you have changes the approach more than it changes whether the job is possible.
Siding |
How access usually works |
What it looks like after |
|---|---|---|
Vinyl or aluminum |
Courses are unclipped, holes drilled, siding replaced |
Nothing visible, the siding hides the plugs |
Wood lap or cedar |
Holes drilled between courses, then plugged |
Plugs are filled and can be painted to match |
Brick veneer |
Holes drilled in mortar joints |
Mortar is repointed, very hard to spot |
Stucco |
Holes drilled and patched, color matched |
Patches are visible until repainted |
Interior access |
Used when the exterior is not workable |
Small drywall patches, then texture and paint |
How it compares to the alternatives
Injection foam is not the only material that exists, but it is the one suited to a closed wall.
Option |
Needs the wall open? |
Fit for a finished older home |
|---|---|---|
Injection foam |
No |
Designed for it. Fills and air seals the cavity in one pass. |
Blown-in loose fill |
No |
Possible through holes, but it can settle and it does not air seal. |
Spray foam |
Yes |
Needs open framing. Realistic during a remodel, not on its own. |
Fiberglass batts |
Yes |
Needs open framing, and batts do nothing about air movement. |
The reason injection foam earns its place in older homes is that it does two jobs in one visit. It adds R-value, and it seals the small gaps inside the cavity that let air move through the wall.
When a wall is a good candidate, and when it is not
Most exterior walls on a pre-1980 home are good candidates. A few situations need a look first.
- Already insulated walls. If the cavity is full, there is nowhere for foam to go. This is why an assessment starts by checking what is actually in there rather than assuming.
- Known moisture problems. A wall with an active leak needs the leak fixed first. Insulating around a water problem hides it instead of solving it.
- Balloon framing and odd cavities. Older framing styles sometimes run cavities in unexpected ways. It is workable, it just needs mapping before the drill comes out.
- Walls that are not exterior. Interior partition walls are not where your heat is going, so they are rarely worth doing for energy reasons.
What changes after
The difference in an older home with previously empty walls tends to show up in three ways. Rooms hold their temperature longer after the furnace cycles off. Interior wall surfaces stop feeling cold to the touch in winter, which is a large part of why a room feels drafty even when it is not. And the equipment you already own runs less to hold the same thermostat setting.
The Department of Energy estimates that air sealing and adding insulation together can cut heating and cooling costs by up to 20 percent for a typical home. Homes that start with nothing in the walls are the ones with the most to gain.
The rebate side
Wall insulation on an existing home may qualify for a rebate through the Avista Utilities Home Insulation Program. The program is built around upgrading a wall cavity from R-0 to R-11 or more, which is exactly what a retrofit does.
The rebate is paid per square foot and the amount depends on which side of the state line you are on. Rebate amounts and eligibility can change, so we confirm the current figures at www.myavista.com/getrebates before we quote.
Find out whether your walls are empty
An assessment tells you what is actually inside your walls before anyone drills anything. We work in Spokane, Coeur d'Alene, Post Falls, and across the Inland Northwest, mostly in homes built before 1980. [insert quote link]
Frequently asked questions
Can you insulate existing walls without removing drywall? Yes. Injection foam is installed through small access holes, usually drilled from the outside, and the holes are patched afterward. The drywall stays in place and no room needs to be gutted.
How big are the holes? Roughly the size of a quarter, with one or two per stud bay. On vinyl or aluminum siding the courses come off first and go back over the plugs, so nothing is visible when the crew leaves.
How long does it take to insulate the walls of a house? Most homes are a one-day job. Size, siding type, and how many obstructions the framing holds are what move the number.
Will injection foam damage my siding? It should not. Vinyl and aluminum courses are removed and reinstalled, brick is drilled in the mortar joints and repointed, and wood and stucco are patched. The approach is chosen around the siding you have.
Does retrofit wall insulation qualify for a rebate? Wall insulation on an existing home may qualify through the Avista Utilities Home Insulation Program, which is built around going from an empty cavity to R-11 or more. Amounts differ by state and can change, so confirm current figures at www.myavista.com/getrebates.
