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Author	Comments
larry kritsch Posted: Nov 18, 2010 10:46 AM	condesation Met with a group of architects yesterday & answered all their questions with the exception of one.In conditioned attic spaces of existing homes (new construction as well) is it possible for condensation to form between the underneath of the roof & the spf which is sprayed to it?If so what is the solution?They were talking ridge vents at the peak of the roof,somehow forming a gap between the roof and foam & then bring air up from the soffit vents in the eves.I'm located in California where temps range the 100's in the summer to maybe a month of high thirtys to fortys in the winter.
jimcoler I have over 10 years of experience specifying and installing open and closed cell spray foam. I've sold my business but I'm still selling for the new owners and consulting on large and custom specific jobs. I've expanded my knowledge into t Posted: Nov 18, 2010 08:59 PM	Yes, this can happen when the foam isn't applied directly to the roof deck. The airspace can allow for condensation to occur. But if you are spraying directly to the roofdeck, then it shoudn't be a problem and I've sprayed many of them with open cell foam. We've had the same request from some architects and builders who just felt more comfortable and we use a product called Low-E reflctive insulaion to create baffles which will allow the air to pass from the soffits to the ridge. It's also flexible and conforms easily to the different angles. Just staple it up and spray away! Hope this helps! Jim
larry kritsch Posted: Nov 19, 2010 09:09 AM	Thank you Jim for the reply.
John Shockney Posted: Nov 19, 2010 09:49 AM	The only problem that I have with adding these baffles, is the studies show that these air passages can bring in more moisture than they vent out causing more problems than they prevent. I would not install such venting unless the architect was signing off on the system!! Hope this helps Airpro
quentin Posted: Nov 19, 2010 11:24 AM	We try to avoid using baffles but around here most of the code officials refuse to pass it unless they are used. It was supposed to be allowed in the new interation of the state building codes and I have called the board many times about getting it but the usual government delays are preventing it.
jimcoler I have over 10 years of experience specifying and installing open and closed cell spray foam. I've sold my business but I'm still selling for the new owners and consulting on large and custom specific jobs. I've expanded my knowledge into t Posted: Nov 20, 2010 10:21 AM	The baffles I'm talking about are a very low vapor perm rated material. It's flexible and can be form fitted to most situations. So, I don't know what studies you have but most of the moisture is coming from the warm air holding the moisture. As long as you have good airflow from the bottom (soffit) to the top (ridge vent), you should be fine. Jim
John Shockney Posted: Nov 20, 2010 10:49 PM	Jim There are some studies that were done by UCSC that showed that during some weather conditions that not enough heat would build up in the vent baffles to create the chimney effect and moist air could come in through the soffit or ridge vent and condense on the roof sheeting as it cooled at night. Also with the complicated roof designs today it is sometimes impossible to get good venting with baffles. Thanks Airpro
Gerry Wagoner Posted: Nov 21, 2010 01:31 PM	Just directly spray to the roof deck. have fun, oG
John Shockney Posted: Nov 21, 2010 03:11 PM	That’s the best answer!!! Thanks Airpro

Author

Comments

larry kritsch

Posted: Nov 18, 2010 10:46 AM

condesation

Met with a group of architects yesterday & answered all their questions with the exception of one.In conditioned attic spaces of existing homes (new construction as well) is it possible for condensation to form between the underneath of the roof & the spf which is sprayed to it?If so what is the solution?They were talking ridge vents at the peak of the roof,somehow forming a gap between the roof and foam & then bring air up from the soffit vents in the eves.I'm located in California where temps range the 100's in the summer to maybe a month of high thirtys to fortys in the winter.

jimcoler

I have over 10 years of experience specifying and installing open and closed cell spray foam. I've sold my business but I'm still selling for the new owners and consulting on large and custom specific jobs.

I've expanded my knowledge into t

Posted: Nov 18, 2010 08:59 PM

Yes, this can happen when the foam isn't applied directly to the roof deck. The airspace can allow for condensation to occur. But if you are spraying directly to the roofdeck, then it shoudn't be a problem and I've sprayed many of them with open cell foam.

We've had the same request from some architects and builders who just felt more comfortable and we use a product called Low-E reflctive insulaion to create baffles which will allow the air to pass from the soffits to the ridge. It's also flexible and conforms easily to the different angles. Just staple it up and spray away!
Hope this helps!

Jim

larry kritsch

Posted: Nov 19, 2010 09:09 AM

Thank you Jim for the reply.

John Shockney

Posted: Nov 19, 2010 09:49 AM

The only problem that I have with adding these baffles, is the studies show that these air passages can bring in more moisture than they vent out causing more problems than they prevent.

I would not install such venting unless the architect was signing off on the system!!

Hope this helps
Airpro

quentin

Posted: Nov 19, 2010 11:24 AM

We try to avoid using baffles but around here most of the code officials refuse to pass it unless they are used. It was supposed to be allowed in the new interation of the state building codes and I have called the board many times about getting it but the usual government delays are preventing it.

jimcoler

I've expanded my knowledge into t

Posted: Nov 20, 2010 10:21 AM

The baffles I'm talking about are a very low vapor perm rated material. It's flexible and can be form fitted to most situations. So, I don't know what studies you have but most of the moisture is coming from the warm air holding the moisture. As long as you have good airflow from the bottom (soffit) to the top (ridge vent), you should be fine.
Jim

John Shockney

Posted: Nov 20, 2010 10:49 PM

Jim

There are some studies that were done by UCSC that showed that during some weather conditions that not enough heat would build up in the vent baffles to create the chimney effect and moist air could come in through the soffit or ridge vent and condense on the roof sheeting as it cooled at night.

Also with the complicated roof designs today it is sometimes impossible to get good venting with baffles.

Thanks
Airpro

Gerry Wagoner

Posted: Nov 21, 2010 01:31 PM

Just directly spray to the roof deck.

have fun,

oG

John Shockney

Posted: Nov 21, 2010 03:11 PM

That’s the best answer!!!

Thanks
Airpro

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