If these insulation companies are suggesting spraying foam over the bottom of the roof and rafters, then they are correct.
- Once the underside of your roof is covered with spray foam, it becomes a part of the inside of your home and it should not be vented.
- They MUST cover the vents.
If they're talking about spraying foam over the top of your ceiling, that's a different matter.They should absolutely NOT cover the vents.
Regardless, before you proceed with the considerable cost of spray foaming your attic, I strongly suggest you have a professional Energy Audit done to your home.
- You need to know whether adding spray is making your indoor air quality better or worse.
- The spray foam companies won't tell you that.
Only a full Energy Audit can tell you how to ensure your indoor air quality is as good as it can be. Possibly there are other issues with your home that can be improved for less money and will give you a better result. Your won't known until you get a professional Audit.
- Find an energy auditorhere in GreenHomeGuide's Find A Pro directory.
- Or go to bpi.org, click on 'Homeowners', then click on 'Find a BPI Approved Contractor Now!' and enter your zipcode.
Good luck, and please come back and let us know what you decide. It helps us all learn.