retrofit wall insulation

[Bill Dufour]

I think my house has no wall insulation. I plan to hire someone to blow in some or spray foam it. My limited experience with contractors is not good. How do I know if they really did dense pack cellulose or fiberglass. Or did they just blow it in loose so not that much insulation value. Spray foam is about the same r-value and it seems less possible to cheat
Bill D

[Jamie Buxton]

Houses old enough to have no insulation might also be old enough to have knob-and-tube wiring. At least in my area, it is against code to put insulation in walls with knob-and-tube wiring. It is something about being a fire hazard.

[Maurice Mcmurry]

The reliable installer in our town uses an infrared device to keep track of what's going on inside the walls and spaces while the job is being done. Around here knob and tube was phased out in the 1930's and was not used in the 1940,s. No insulation went on until the 1960's
Our town outgrew its power plant years ago and now has an energy efficiency program. The city will do a free home energy audit with a blower door test and infrared scan. The before and after results are neat to see.
-Maurice

[roger wiegand]

Check and see if your state or utility company offers a free energy audit, they can be very useful. In many states those programs offer substantial rebates or free services ($2K/year in MA) for insulation and air sealing. At least in MA any work done under the program (MassSave) is inspected by the program, including imaging with a thermal camera to look for under-insulated spots.

In an existing house, especially in a moderate climate like CA, blown in dense pack cellulose is a very good option, certainly the most cost effective. The material is cheap, so there's not much incentive to under fill. With foam there are way too many horror stories of poor cures inside the walls, over-fills cracking or bulging the walls with expansion, and unfilled spaces. Much better when you have access to open walls.

[Lee Schierer]

You can view the warm and cold areas of your walls with a infrared camera. FLIR ONE Gen 3 - iOS - Thermal Camera for Smart Phones works with some smart phones. You can take before and after images with the camera to see how the thermal properties of your walls have changed.

[Jim Becker]

One major challenge for any blown-in retrofit in walls, regardless of insulation type, is blocking in the wall. Keep that in mind as it can sometimes be haphazard, too.

As to the contractor, there are a variety of ways to view reviews and other forms of information about contractors. Multiple sources need to be looked at and even then, a "grain of salt" is a good idea. Getting a referral from local successful general contractors is a good idea, too. I always ask a GC I used for a major addition at our old property who over the years has also become a good friend for recommendations when something is beyond what I want to tackle myself.

[Bill Dufour]

House was built in 1969 with modern plastic insulated wiring. Local utility had a lending Library including a $14,000 flir camera. Shut down for covid.
I have a feeling that home energy audits are no longer in person? Sense I got from a quick read was they tell you go look for this and that see if you have good windows, insulation, calculate it yourself.
Bill D

[Jim Becker]

Perhaps there are some places you can do some small holes (repairable) to spot check for insulation? There are also relatively inexpensive borescopes that work with smartphones available to help you further explore things to see what's in the wall now. I bought one not long ago to scope the soffit above our kitchen range area to ascertain if I had a pathway available to the outside for proper venting. Mine came from Amazon.