Insulating Cement Block walls | Ask Mason Knowles - SPF Consultant | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

Q&A Forums

Author	Comments
John Kelly Posted: Nov 15, 2008 07:10 PM	Insulating Cement Block walls Does it make sense to consider spray foam for insulating block walls by injecting the foam into the hollow cavity of the block itself?
mason Posted: Nov 16, 2008 09:59 AM	this used to be fairly common practice 20 to 30 years ago. I insulated many a block wall with a pour in place polyurethane foam. Nowadays, they typically use a low density tripolymer foam to insulate the cavity. For my money, I like the closed cell foam better for its water resistance and extra insulation value. A spray foam would not work. The exothermic heat reaction would be too high. Even with a pour in place foam, you have to be careful not to pour over the rising foam. Also, the foam has a tendency to creep out of any crack or crevice along the bottom of the wall. Froth foams can be used also. These foams use a third stream blowing agent to pre-expand the foam and reduce the pressure and heat. Ask your supplier if they have a foam for block wall fill and some instruction on using it. It does require a technique that must be learned in order to do the job properly.

Author

Comments

John Kelly

Posted: Nov 15, 2008 07:10 PM

Insulating Cement Block walls

Does it make sense to consider spray foam for insulating block walls by injecting the foam into the hollow cavity of the block itself?

mason

Posted: Nov 16, 2008 09:59 AM

this used to be fairly common practice 20 to 30 years ago. I insulated many a block wall with a pour in place polyurethane foam. Nowadays, they typically use a low density tripolymer foam to insulate the cavity. For my money, I like the closed cell foam better for its water resistance and extra insulation value.

A spray foam would not work. The exothermic heat reaction would be too high. Even with a pour in place foam, you have to be careful not to pour over the rising foam. Also, the foam has a tendency to creep out of any crack or crevice along the bottom of the wall.

Froth foams can be used also. These foams use a third stream blowing agent to pre-expand the foam and reduce the pressure and heat. Ask your supplier if they have a foam for block wall fill and some instruction on using it. It does require a technique that must be learned in order to do the job properly.

You need to login to reply to this topic. Please click here to login.