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Unvented attics Post New Topic | Post Reply
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kevin fowler
Posted: Mar 04, 2006 06:16 PM
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Unvented attics
If you are spraying roof decks but not using vented soffets or ridge vents do you still have to ventilate the attic space? The entire structure including crawlspace will be sprayed with .5lb foam. Is additional ventilation required?
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Posted: Mar 06, 2006 10:41 AM
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No natural ventilation at the decking is not needed. However with any tight, efficient building envelope design,some form of mechanical ventilation should be used. Remember however that your local codes may require some sort of secondary vapor retarder with open cell foams. |
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Posted: Mar 12, 2006 03:32 AM
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i am assumeing you mean to the undersurface of the roof sheeting to create a conditioned space... conditioned space,,,natural ventilation not needed..mechanical ventilation needed.. WARNING WILL ROBINSON: if you planning to shoot to the drywall lid be sure to check with your local code official to see if the "exposed foam" in the attic area will be permittable...some require a covering with a fire/thermal barrier..this will add a whole new twist to your application, and you need to know going in,,,not after the fact... my experiance is that this varies from jurisdiciton to jurisdiction,,,and sometimes the inspectors interpitation is hillarious,,but costly... I ENCOURAGE YOU TO READ ALL YOU CAN ABOUT BUILDING SCIENCE AND THE BUILDING ENVELOPE TO INCLUDE VENTILATION ISSUES there is a wealth of good info out there.. educate your self..it is your liablity and reputation |
