consistant depth of open cell | Ask Mason Knowles - SPF Consultant | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

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Doug Crenshaw Posted: Jun 11, 2008 09:55 PM	consistant depth of open cell I just had open cell sprayed in my attic roof area. I have 2X6 rafters and some 2X4 knee walls. I chose 3.5 inches over 5.5 inches because our future use of the attic as living space is slim to none and of course the additional cost. The foam depth varies quite a bit. It ranges from 2 inches to 6 inches or more. Question: Will the inconsistant depth be much less effictive than a than a continuous 3.5 inches?
richard sucher II Posted: Jun 12, 2008 08:20 AM	based on what you have said, you should have full cavity on knee walls and minimum 3.5" thickness in floor cavity. contact contractor and have him come pack and re-spray the areas that are below the 3.5" minimum. Would hold payment until you are satified. There is no excuse for 2.0 inch thickness. Six inch is good for you but not what you asked for. You agreed to 3.5" minimum and that is what you should get. You did not buy "average" thickness - you bought minimum thickness. Good luck.
mason Posted: Jun 12, 2008 07:25 PM	I agree with Cobb on this one. Having less than the specified amount can cause thermal bridges in the areas where the foam is thin. Heat can easily transfer in the thin spots and you cannot "make it up" in the thick spots. The basic industry policy is to have minimum thickness within a 1/4" tolerance unless otherwise specified

Author

Comments

Doug Crenshaw

Posted: Jun 11, 2008 09:55 PM

consistant depth of open cell

I just had open cell sprayed in my attic roof area. I have 2X6 rafters and some 2X4 knee walls. I chose 3.5 inches over 5.5 inches because our future use of the attic as living space is slim to none and of course the additional cost.

The foam depth varies quite a bit. It ranges from 2 inches to 6 inches or more.

Question: Will the inconsistant depth be much less effictive than a than a continuous 3.5 inches?

richard sucher II

Posted: Jun 12, 2008 08:20 AM

based on what you have said, you should have full cavity on knee walls and minimum 3.5" thickness in floor cavity. contact contractor and have him come pack and re-spray the areas that are below the 3.5" minimum. Would hold payment until you are satified. There is no excuse for 2.0 inch thickness. Six inch is good for you but not what you asked for. You agreed to 3.5" minimum and that is what you should get. You did not buy "average" thickness - you bought minimum thickness. Good luck.

mason

Posted: Jun 12, 2008 07:25 PM

I agree with Cobb on this one. Having less than the specified amount can cause thermal bridges in the areas where the foam is thin. Heat can easily transfer in the thin spots and you cannot "make it up" in the thick spots.

The basic industry policy is to have minimum thickness within a 1/4" tolerance unless otherwise specified

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