How to Choose and Use Insulation | This Old House

This Old House general contractor Tom Silva explains the wide world of insulation. (See below for a shopping list and tools.)

Up in the loft, Tom and Kevin discussed different types of exterior wall insulation and how they're installed, both for new construction and retrofit situations. The materials included liquid spray foam, recycled denim batts, fiberglass batts, blown-in fiberglass, and cellulose. Installation of vapor retarders over insulation was also discussed.

Shopping List for How to Choose and Use Insulation:

Tools for How to Choose and Use Insulation:

Tom showed Kevin a variety of materials used for insulating exterior walls, including Fiberglass Batts (faced & un-faced), blown-in fiberglass and liquid foam (open & closed cell).

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Homeowners have a virtual truckload of questions for us on smaller projects, and we're ready to answer. Ask This Old House solves the steady stream of home improvement problems faced by our viewers—and we make house calls! Ask This Old House features some familiar faces from This Old House, including Kevin O'Connor, general contractor Tom Silva, plumbing and heating expert Richard Trethewey, and landscape contractor Roger Cook.

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How to Choose and Use Insulation | This Old House

[realtree]

I remember as a kid, being very annoying at the adults watching this old house. Now I’m an adult watching it and love it..

[WakandaBabe]

I just had my attic air sealed before I added new cellulose insulation. The process was: All the old insulation was removed. Then an electrical contractor rewired the entire house; all knob and tube wiring was removed, not just deactivated. After the electrical inspection by the city, the insulation guys came back and air sealed the attic. They used foam board and various foams for cracks, etc. I saw pictures of what they did and the amount of work that was done was amazing. They also air sealed my basement in the same manner. Then new insulation was blown into the attic and more insulation was blown into the outer walls of the house. All the insulation work was done by a BPI certified contractor. Then an inspector came with a heat device and checked the heat loss. A few spots in the walls needed to be 'topped off' and that was done. The difference in my house is amazing; no more cold spots! I have a 1927 Craftsman Bungalow so I still have, and intend to keep, all the original windows, so heat loss happens there. I have caulked all the windows. I am working on getting interior storm windows but in the meantime, I put up plastic coverings. Even with the old windows, the house is significantly warmer. What a difference.

[FranciscoMartinez-zvrw]

Finally found what I was lookin for!!!! No other video talked about which direction the moisture barrier should be on!!!! Thanks you tommy

[jamesedwards]

So glad you guys touched on vapor lock with the visqueen some very stubborn people would not listen to me about it

[ShiningSakura]

I'm surprised they didn't talk about mineral wool or even sheeps wool as insulation. Sheep wool is a bit niche but mineral wool is very popular and readily available.

[ericdurrwachter]

Building new house in 2021, wanted to go with closed cell, but with increased lumber costs went with wet sprayed cellulose. Thanks for the informative video!

[mikegrimaldi]

Wish they talked more about the vapor control layer. It’s a topic on its own so may involve lots of details when/where/why to use.

[rdooski]

Thanks to everyone in the comment section that mentioned rockwool. Its seems impossible but somehow I had never seen or heard of it. And it has all of the qualities I was looking for.

[donnyjackson]

I did Rockwool with Certainteed Membrain as the vapor retarder on my new build.

[ctail]

Tom Silva is a genius. I would love to work with this guy

[clarasantiso]

Love, love, love the detail in explaining the subjects of these men.

[rekinlas]

In my denver 1.5 story home, i could not get the upstairs below 78 on hot days with the AC cranking full time. (My system was working properly but flow upstairs was weak). My cellulose insulation was only about 15 inches. I had a contractor add "caps" to the 15 can-lights and seal them, top off the insulation to 36 inches, and foam a few spots like where my two-story living room wall abutted the attic over the garage. The difference was amazing. If the AC is on, the upstairs is about a degree warmer than the 73 degree main floor, and the AC will now cycle. But even on hot days, if i run the house fan at night, the house is cool enough to where i wont need the ac until the afternoon, if at all.

[JerryJohn]

Thank you so much! This is awesome information for a first time home owner like me

[victorseal]

Good information. But, no mention of what I found to be the best of all, Rockwool !

[Dbell]

Hi Tom and Kevin,

This is a great and very informative video—thank you so much!
Quick question: I live in Houston, TX, and we recently had temperatures drop to 25 degrees for about three days. I noticed that the room above my garage gets very cold. Are contractors required to insulate the garage ceiling? If it’s not insulated, how would I go about using spray foam to fix this? I’d really appreciate it if you could reference one of your videos if you’ve covered this topic.
Thank you!

[davidthompson]

Something no one talks about and most people don't realize is that the rigid spray foam insulation offers no sound proofing. My neighbor spent a fortune insulating his entire house with it and now he can hear someone's conversation on the sidewalk as if they were in the same room. Personally, I would spend the money on ICF instead.

[robinanddad]

good information good old pink never let us down

[Spooms]

Brilliant! Thank you for clarifying some of the basic ideas with insulation. Well done guys.

[ellypotamianos]

Which is the best retrofit material for a cathedral ceiling through the fascia & soffit to add present bat insulation in Illinois weather. Venting along the soffit was shut due to the moisture condensation inside & vents at top of roof left open cause scaling at top of beam inside. Thermal imaging was done and the corners & a 4 x 5 foot area over the front door was missing insulation. Advise would be greatly appreciated.

[LavinaSINGH-op]

I bet everyone here is an adult and loves watching their videos bec it useful to them, while my science teacher sent me 21 videos of this Chanel to watch, which I am dying from