Thread: Expanding foam on roof deck?

I just inspected a new home with expanding foam insulation sprayed into the attic along the roof deck. There were several locations where I could see gaps. The whole job looked like it was done by cans.
The last I saw a video on this type of insulation, it was sprayed with a special wand that filled the cavity between studs and then they scraped off the excess along the face of the studs. They never talked about roof decks.

When I checked further I found that the roof deck was wet. I tried three locations and my moisture meter went to 40 and 50%. Also the builder did not install venting. No soffit, eave, ridge or gable vents.

Trying to keep this short. The builder is saying that all this is fine. That the foam keeps oxygen from contacting the roof deck, so no venting is required. Which may be, if it was installed correctly.

Personally I hate the stuff because I can't pull insualtion away to make sure things are ok. Anyway, it looks like I may be butting heads with this builder since I think the stuff should be removed. So before I get into this, can anyone inform me about using, not using foam on the attic roof deck?

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That looks like a really poor job, but foam on the underside of the roof deck is and accepted method (if done correctly).

Done correctly (and that does not look like it was done correctly) it is allowed, some actually prefer it, I am on the fence about it.

The reason I am on the fence about it is precisely because of what you found - roof sheathing with high levels of moisture which would not be revealed until someone on the roof falls through rotted roof sheathing.

Other than that ... ... it seems to be a good product.

Every product as its pluses and minuses, pros and cons, and that is the big con for that spray on foam insulation.

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Here us a little info (very little).

Originally Posted by Peter Drougas

...The builder is saying that all this is fine. That the foam keeps oxygen from contacting the roof deck, so no venting is required. ...

This sounds bogus. Is the builder saying wet decking is ok as long as air/oxygen can't get to it?

I am wondering what effect that kind of installation has on the shingle manufacturer's warranty. Can we call this "vented to Code?"
DEtroit Matt

As everybody else has said, it is acceptable if done correctly. However, the presence of gaps is not acceptable.

Also, the idea of insulating on the roof deck is to form a "sealed" system comprised of the entire building envelope. Therefore, the larger problem in your picture is the absence of foam insulation in the wall. If done in an acceptable manner, every exterior surface is foamed so that the house is like a styrofoam cooler. If that is done, attic ventilation is not appropriate. Your picture shows a botched job.

Darrel Hood
DILIGENT PROPERTY SERVICES

Pls excuse me I'm new, but curious. Question: is this house finished or underconstruction? Is the attic space to be conditioned or unconditioned. Since the exterior wall is not insulated I'm thinking unconditioned. I'm curious about this because of the lack of roof deck ventilation and what the resulting effects are using this insulation system.
Also how were you able to check moisture if the roof deck was covered with this hardened goo?

Originally Posted by Matt Bezanson

I am wondering what effect that kind of installation has on the shingle manufacturer's warranty. Can we call this "vented to Code?"
DEtroit Matt

Matt,

Yes, it is "vented to code" as code requires venting except ... and that is the exception.

Thus the better way to say it would be to say it was "unvented to code". Except THAT one is in no way "unvented to code", THAT one is simply "botched up".

Originally Posted by Darrel Hood

Also, the idea of insulating on the roof deck is to form a "sealed" system comprised of the entire building envelope. Therefore, the larger problem in your picture is the absence of foam insulation in the wall.

Darrel,

I was making a presumption that this was an in-progress inspection (we all know what happens when we presume or assume something) and that the exterior wall had not been done ... 'yet' ...

If the house is completed, absolutely that attic was not done in a manner in which an unvented "sealed" attic is to be done.

I posted my previous post before reading your post and noticed that we both came to the same conclusion - that job has been "botched", not a word we typically use here, and two of us used it for the same thread. Just found that interesting.

James,

First - Welcome to THE inspectors board.

Second, you ask a very important question, one in which the answer is quite important

Originally Posted by James Skinner

Question: is this house finished or underconstruction?

.

Hopefully Peter will respond with that answer.

Is the attic space to be conditioned or unconditioned.

When unvented sealed attics used, the space becomes what many call "semi-conditioned" because, while the attic is not intentionally conditioned in many (most?) unvented sealed attics, the attic 'is' within the thermal envelope and does affect the heat/cooling requirements of the equipment.

If the attic pictured is to be finished off into a room, which it looks like it might be with that large window, then it would become conditioned space without question.

Since the exterior wall is not insulated I'm thinking unconditioned.

With the exterior wall uninsulated, that type of attic insulation is not allowed and is useless.

Which gets us back to the question of "is this in-progress or is this finished"?

I'm curious about this because of the lack of roof deck ventilation and what the resulting effects are using this insulation system.

There have been many tests and evaluations run and insulating the underside of the roof sheathing is not supposed to have any significant effect on the temperature or the life of the singles.

Also how were you able to check moisture if the roof deck was covered with this hardened goo?

I pondered that to, but he said there were gaps, so I presumed (there is that dreadful word again) ... I presumed he checked where the gaps were.

Peter,

If you want to read about unvented attics go to Building Science Consulting . If you are going to foam the rafters then do not install perforated soffits. You can still use blown insulation in the walls and have a whole house thermal boundry. This allows the air handlers and ducts to be placed in a "conditioned space". Many of these attics have 2 A/C supply ducts in them. If the A/C units are sized correctly they should remove the moisture from the house. In some very tight houses mechanical ventilation is required.

OK here's my thoughts.

Since this is an area that is going to be used as occupied space and the rafters are sized to be an open span, larger than 2 X 6, probably 2 X 8 or larger, and it is going to be a conditioned space, then the amount of spray foam needed to comply with energy codes was not enough to fill the rafter cavity.

What the installers did was give them the minimum amount needed since anything above that would be "giving" extra insulation away. That is why it looks so ugly. If the builder wanted to pay for the additional then I would speculate they would have filled it level with the bottom of the rafters and then removed the excess insulation to make it a prettier application.

The spray foam may have been water based and that may have given you a moisture reading that was so high.

This type of installation is getting very popular in our area. We have one builder that this procedure is the only way they will insulate their homes. Very energy efficient!

The house was basiclly finished, just some finish work to be done. The attic is at the front half of the house only. Cathedral to rear. But you can see arcoss the cathedral ceiling that the foam continues. The attic access is an opening in the wall of the hallway, no door yet.

The gable wall had fiberglass insulation, but was removed due to (ta da) moisture and mold (an event prior to my inspection)

I got agressive and pushed my hand through a low spot in the foam to place my moisture meter in. When it came up 50%, I pulled two more random locations. This is also how I determined the stuff was not installed correctly, as I found pockets of no contact to the sheathing.

Thanks everyone for your inputs. Feel free to continue, but I have what I need. Non-professional installation will be my key point.

If you think about it that is all SIPs are. OSB, foam, osb or drywall. Great insulator but you have to keep up on your roof and insect infestation. Insects love to live in there. Anyone with any type of foam insulation has to be much more aware of the condition of their home and have an active pest control contract. If I ever build another home it will be with sips. Light a candle for heat or leave some ice cubes out to cool the home