Adding 2 Inches of closed Cell.. | Ask Mason Knowles - SPF Consultant | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

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Posted: Mar 14, 2009 11:10 PM	Adding 2 Inches of closed Cell.. Hi Mason I will be adding 2 inches of closed cell to an existing freezer that was spray foamed a couple of years ago using some type of two part spray foam that came in large cylinders. The product is pretty popcorned on the walls and appeared that the product was cold when it went on. I will be coming in and putting 2 inches of closed cell (22,000 board ft total) in the first week of April in Port Arthur, TX. Should I do a whole lot of prep work on the existing spray foam. It is intact and is not in danger of coming off. I figured that I would just blow any dust off and start spraying. Do you have any suggestions? The freezer has been off since Ike came through in September and is dry, ready to go. Steve
mason Posted: Mar 15, 2009 08:17 AM	Take a few core samples of the foam and check the cell structure of the foam, compressive strength and the condition of the substrate under the foam. If the foam was cold when it was applied (or the substrate) there will be a thin layer of very high density foam next to the substrate. This layer can crack and lead to poor adhesion later on. You say the foam surface is popcorn, Make sure that it does not have any off ratio foam, soft spots in or on the foam. You may have to clean the surface of the foam to remove any dust or contaminants that have settled on the surface of the foam. Check out the adhesion first by spraying a small section of the wall (2 to 3 sq ft) Let it set a few hours, then cut out a core sample. Look for poor cell structure between the new foam and old foam and poor adhesion. It should stick to the old foam just like it was new. If not, you may have to scarf the surface of the old foam. Or remove it all together if the foam has poor physical properties. Also, make sure the substrate has a vapor barrier installed under the foam. If not, you will have a problem with condensation. If it does not have a vapor barrier you will have to remove the old foam and spray a vapor barrier coating first, then spray the new foam.

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Posted: Mar 14, 2009 11:10 PM

Adding 2 Inches of closed Cell..

Hi Mason

I will be adding 2 inches of closed cell to an existing freezer that was spray foamed a couple of years ago using some type of two part spray foam that came in large cylinders. The product is pretty popcorned on the walls and appeared that the product was cold when it went on.

I will be coming in and putting 2 inches of closed cell (22,000 board ft total) in the first week of April in Port Arthur, TX.

Should I do a whole lot of prep work on the existing spray foam. It is intact and is not in danger of coming off. I figured that I would just blow any dust off and start spraying.

Do you have any suggestions? The freezer has been off since Ike came through in September and is dry, ready to go.

Steve

mason

Posted: Mar 15, 2009 08:17 AM

Take a few core samples of the foam and check the cell structure of the foam, compressive strength and the condition of the substrate under the foam. If the foam was cold when it was applied (or the substrate) there will be a thin layer of very high density foam next to the substrate. This layer can crack and lead to poor adhesion later on. You say the foam surface is popcorn, Make sure that it does not have any off ratio foam, soft spots in or on the foam. You may have to clean the surface of the foam to remove any dust or contaminants that have settled on the surface of the foam.

Check out the adhesion first by spraying a small section of the wall (2 to 3 sq ft) Let it set a few hours, then cut out a core sample. Look for poor cell structure between the new foam and old foam and poor adhesion. It should stick to the old foam just like it was new. If not, you may have to scarf the surface of the old foam. Or remove it all together if the foam has poor physical properties. Also, make sure the substrate has a vapor barrier installed under the foam. If not, you will have a problem with condensation. If it does not have a vapor barrier you will have to remove the old foam and spray a vapor barrier coating first, then spray the new foam.

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