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joerosato
Flip the attic insulation?

70 yr old house in South Jersey.

Attic insulation installed upside down.

Should I flip the insulation or install new insulation on top of the existing insulation or instal plywood over the existing insulation?

Thanks.

RJordan
Re: Flip the attic insulation?

As someone who does a lot of retro work in existing houses by installing spray foam to the underside of the roof deck, I see a lot of fiberglass that is not working. My advice is to not waste money on fiberglass.

Timothy Miller
Re: Flip the attic insulation?

Howdy depending on how much R value you have and want is the best evaluation you can have an insulation contractor out to check and bid what to add if anything. Cellulose blown over fiberglass is a good choice as it stops air movement that fiberglass does not and it allows moisture vapor to pass threw it.

RJordan
Re: Flip the attic insulation?

First,you need to pull the fiberglass back and seal all the penetrations into the attic. Cellulose does not stop air movement. It is better than fiberglass though.

Timothy Miller
Re: Flip the attic insulation?

Howdy, ok its not a closed cell but have you ever seen air move threw cellulose? Really try a air test easy one is with a screen and 6 inches of cellulose and the discharge air from a shop vac not to close to make it fly but i think you will find it blocks air flow nicely. Ok its an air retarder thats better.
Also consider caulking the ceiling light fixtures to again retard air infiltration into the attic.

RJordan
Re: Flip the attic insulation?

If you take Building Performance Institute training or attend conferences like Affordable Comfort, everyone stresses the need to stop air infiltration by sealing before adding cellulose.

Timothy Miller
Re: Flip the attic insulation?
RJordan wrote:

If you take Building Performance Institute training or attend conferences like Affordable Comfort, everyone stresses the need to stop air infiltration by sealing before adding cellulose.

Even if you do not take a class to seal for air infiltration souses regardless of the type of insulation is common sense like zipping up your coat when you feel a breeze.... No one seems to be arguing that foam is good to use but its not the end all.

canuk
Re: Flip the attic insulation?
Timothy Miller wrote:

Even if you do not take a class to seal for air infiltration souses regardless of the type of insulation is common sense like zipping up your coat when you feel a breeze.... No one seems to be arguing that foam is good to use but its not the end all.

Certainly the biggest issue with spray foam is the cost --- personally SIF could be about 30% cheaper ---- but ---- supply and demand.

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