Wall Insulation for Existing Homes

There are several options when it comes to wall insulation in existing homes. Most commonly a number of holes are drilled to allow injection of insulation foam but there are times when it is better to open up the wall from the outside to gain full access. We call this second approach the “Outside-In”. Both methods are described below.

The Traditional Approach to Wall Insulation

Wood frame walls

Pure Seal uses Air Krete wall foam for insulation of closed wall cavities. We chose Air Krete after careful evaluation of competing systems and materials for the following reasons:

· Air Krete offers outstanding R-value.
· Air Krete flows around obstructions in the wall during installation, which prevents voids in the insulation.
· Air Krete does not shrink or settle in the wall, which eliminates unwanted air infiltration. Competing retrofit foams can shrink which allows cold air to bypass the insulation, significantly reducing is value.
· Air Krete is class “A” fire rated. It simply will not burn, which is an important consideration especially in homes with older style wiring.
· Air Krete repels insects and rodents and will not support mold growth.
· Air Krete is a true Green product. Air Krete is based on Magnesium Oxide, contains no carcinogenic fibers, no CFCs or formaldehyde. Air Krete is odorless and free of toxins that may affect the chemically sensitive.

We believe that Air Krete is a superior product with significant advantages over competing systems for closed cavity insulation.

Masonry walls

Walls with several layers of brick may have a usable air gap between the layers. If so, they can be insulated internally with Air Krete.

Solid masonry walls without interior air gaps are best insulated as part of a remodeling project where a new wall cavity is created on the inside of the wall to hold new wiring and insulation. In order to prevent condensation, it is critically important that the wall be insulated with an air impermeable insulation material; in practical terms that means that it must be insulated with spray foam. We insulate masonry walls with closed cell polyurethane spray foam, which controls air and moisture flow and provides excellent R-value in a limited amount of space.

The installation process

The most common way to insulate walls in existing homes is drill holes into the wall cavities and install the insulation through a hose. As explained above, we use Air Krete cementitious wall foam for this type of work. Most walls with an interior cavity can be insulated with Air Krete and it works extremely well.

Century home in Gates Mills, OH
The first step in the insulation process is to remove siding, in this case cedar clapboards and shingles (Gates Mills. OH)
Brick is also possible
Brick walls require smaller holes drilled through the mortar joints as shown in this photo (Cleveland Heights, OH)
Holes are drilled through the planking
It is necessary to drill one hole for every stud bay, typically every 16 inches (Gates Mills, OH)
Prepping for Air Krete from the inside
Probing the cavities
On old homes like this one, the framing is rarely regular and we probe the cavities to check for obstructions (Gates Mills, OH)
Checking product specifications
Before we install the Air Krete wall foam, we verify that the product meets the manufacturer's specifications (Gates Mills, OH)
Air Krete being installed.
Air Krete can be pumped through a hose, which allows us to fill the wall cavity through a hole. This is not possible with rapidly expanding polyurethane spray foam (Gates Mills, OH)
Siding reinstalled
After the wall cavities are filled with Air Krete, the siding can be re-installed. In this case we used galvanized nails to fastened the original cedar clapboards (Gates Mills, OH)
Inside job, insulated and plugged
The holes are sealed with styrofoam plugs that can be easily finished with drywall compound.
Hole in brick wall after installation
Brick walls are insulated through small holes drilled in the mortar joints. They are sealed after installation (Cleveland Heights, OH)
Once the siding is in place we can wash away any traces of Air Krete, which cleans up easily (Gates Mills, OH)
Final touches on wood siding
Old paint will tend to chip and there are nail holes to be dealt with. We apply exterior grade spackling compound and touch up with owner-supplied paint (Gates Mills, OH)


I have a brick veneered wood framed ranch home built in the mid 1960’s. Even though the prior owners had installed energy efficient windows and doors, the home was drafty and expensive to heat/cool. The exterior walls had what passed for insulation at the time it was built but the fiberglass insulation had begun to break down, shrink, the paper vapor barrier was cracked and pulled away from the studs. In addition, a few of the exterior walls had knob and tube wiring in them that would have been difficult at best to replace.
While researching what was available to retrofit into the exterior walls, I ran across Air Krete expanding injectable insulation. I contacted Torsten at Pure Seal in Mentor, Ohio to get a quote. Torsten came out and gave me so much valuable information on the best way to insulate my house that I knew his company was the right one for me.
The crew drilled holes in the mortar joints between the bricks and injected the Air Krete into the wall cavities all the way around the house. They then went into the attic and Air sealed the ceiling before installing baffles and blowing an R-60 insulation in the attic. The crew was very professional, worked fast and cleaned up so well you would hardly know they were ever there. The mortar patches they put into the holes they drilled matched the existing color very well. I had recently had a new roof with ridge venting installed but Torsten said there wasn’t enough soffit venting so I had continuous soffit venting put in to finish the project.
The difference in the house is amazing, the house is quieter, much less expensive to heat and cool and the drafts are gone. The enormous icicles hanging from my gutters also went away.
I would gladly recommend Pure Seal to anyone. Torsten is a wealth of information that really helps making the right decisions easy.
Jeff Stryffeler
Middleburg Heights, Ohio

An alternative approach – the Outside-In

The Outside-In method is the ultimate approach to re-insulating existing walls without tearing the inside of your home apart. It involves removal of siding, sheathing and old insulation. This allows us to use polyurethane spray foam, which gives the very best air sealing and to seal the gaps between framing members. We have done whole houses this way but it is more common to focus on small areas that are particularly troublesome. Bathtubs that are too cold to use in the winter are a common example. Another would be walls with freezing pipes.


Indoor ice
Sometimes a problem calls for drastic measures. This customer (see testimonial) had ice on the inside of his walls caused by sub-standard insulation and air sealing, which caused indoor humidity to condense and then freeze.
Siding is removed and marked
We remove siding as needed and mark it so that everything can be put back together at the end of the project. As you can see, this house had no weather barrier material under the siding.
Somebody had a bad day
We never know what we will find but gaping holes and poorly fastened sheathing are common
Another example of holed sheathing
Poorly installed fiberglass
Notice the dark deposits in the insulation. This is dirt from moving air.
Foaming in progress
This 1950's ranch received a complete update of electrical an insulation systems
Crossbracing easily accommodated
Modern efficiency in older home
Final steps
After the foam is applied, the wall is re-sheathed and protected with proper house wrap before the siding is installed.



“During the ‘polar vortexes’ in years past, my house began accumulating ice on the inside, causing the drywall to crack and split. After consulting with 5 different contractors, I was finally referred to Torsten at Pure Seal. Torsten quickly recognized the problem after speaking with me and came out the next day for an onsite inspection. He brought binders and charts to help explain the scientific dynamics of the internal freeze. More importantly, he developed a viable solution for the problem. The work was scheduled and completed in the Spring. Torsten was onsite to manage the project, though his crew was exceptional, professional, polite, and thorough in completing the work. Torsten showed me the areas where my builder had cut corners and failed to properly insulate the house, ultimately causing the damage. But most importantly, Torsten engineered and implemented a solution that has held up under northeast Ohio’s extreme weather. My utility bills are down, my walls are warm, and my house is safe. I’m extremely grateful for the peace of mind Pure Seal’s products and services have provided! I highly recommend Pure Seal to those seeking insulation solutions!

Jonathan Wolnik”

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