SIP Panel Heat Loss

kettleviewtimber · April 22, 2010, 07:10:40 PM

Is this normal for roof SIP panels? There is no thermal break where the two panels meet.

bigshow · April 22, 2010, 11:20:52 PM

ouch. that dont look right...not right at all.

Jim_Rogers · April 23, 2010, 07:08:10 AM

To me that is an obvious sign that the seams between the panels were not completely foamed to fill the gaps.

Did you install the panels yourself?

Raider Bill · April 23, 2010, 07:38:20 AM

That can't be good :-\
Is there a attic or space between the room and sip?

scsmith42 · April 23, 2010, 08:45:07 AM

Quote from: Jim_Rogers on April 23, 2010, 07:08:10 AM
To me that is an obvious sign that the seams between the panels were not completely foamed to fill the gaps.

+1.

Brad_bb · April 23, 2010, 09:17:38 AM

+2

frwinks · April 23, 2010, 10:17:34 AM

I hope the installer will stand behind their work and reinstall the panels

I found this article a while back when researching sips, Joe Lstiburek explains the problem in great detail...
http://www.sips.org/content/technical/index.cfm?pageId=161

good luck

witterbound · April 23, 2010, 10:43:25 AM

I helped a crew install panels on two houses about 4 years, so I'm no expert. But the panels we installed weren't designed to have any foam sprayed in the seams between the panels, I don't think. One panel had a 'groove' and the other panel had a 'tongue.' Foam rubber weatherstripping was installed on the 'grove' side, I think, then they were pulled tight together. Are these seams normally foamed when the sips are installed?

Jim_Rogers · April 23, 2010, 03:41:50 PM

Quote from: witterbound on April 23, 2010, 10:43:25 AM
Are these seams normally foamed when the sips are installed?

I thought that most panel companies did do channels between the panels for foaming.
I don't know why they wouldn't.

The company near me has some info in their installation guide and I have some screen captures from that guide:

And to know that every joint was foamed and every hole was "over filled" the job should look like this before the excess is removed:

If the above sips, shown in the first post, was not foamed between the panels then this is where the heat is leaking out of the house, into the roofing materials.

Jim Rogers

Also:

kettleviewtimber · April 23, 2010, 10:10:25 PM

This is a picture of us installing the panels. The seller (Pacemaker) only had us caulk the joints there was never any mention about foaming the joints. Also there were no channels cut in the panel for foam. Never go with the low bid that has a salesman that talks a big game.

Do you think I'm going to have a moisture problem? I haven't seen any moisture issues from the inside.

Jim_Rogers · April 24, 2010, 07:15:37 AM

From one of the downloads from the pacemaker site, I found this view of a joint:

If your roof has joints like this, it could be why you're having a thermal leak. The wood (2bys) between the panels are allowing the heat to transfer out to the roof.

When moisture in the inside air hits a cool or cold surface then it could condense. I'm not saying you will have problems, you may not.
Time will tell.

kettleviewtimber · April 24, 2010, 08:54:23 AM

Yes, The double 2X's are one type of joint that is in the roof. The spline is the other type you can tell by the pictures where the spline joints are and the double 2X's are. The 2X's are at the valleys and dormers and the splines are in the center of the roof.

Here are other problems that I had with Pacemaker. The Cad guy at Pacemaker was new so some of my wall panels had windows right at post and knee brace locations. One wall panel (middle picture) had the wrong roof pitch.

Brad_bb · April 24, 2010, 09:54:27 AM

Wow, I feel for you. Thank you for sharing. It's a great lesson for all those who read this. You're likely saving someone here some headache by educating them (or me). Let us know if you plan to tear the roof down and redo it.

Jim_Rogers · April 24, 2010, 12:21:42 PM

As far as your moisture problem question goes, if you followed the recommended vapor barrier installation as shown or noted in the installation guide you shouldn't have a problem.

Magicman · April 24, 2010, 12:30:05 PM

I watched a SIP house being built. They installed the roof one day, took it all off the next, and then reinstalled it the next. I think that maybe someone didn't know what they were doing..... ???

witterbound · April 26, 2010, 10:08:01 AM

Again, I 'm no expert on this, but I've got to tell you that this roof doesn't look that abnormal to me. When you drive by most regular homes, you see the frost melting over the rafters first. SIPs have seams, and there is no way those seams can be as tight and well insulated as the rest of the roof, so the frost just has to melt on those seams first. But I'm no expert.....

Aikenback · April 26, 2010, 04:18:15 PM

I think Witterbound is right. There is more thermal absorbtion where there is more wood(at the joint spline), whereas the styrofoam resists the heat. Same where the rafters are in a conventional house. The air between rafters conducts builtup heat away from the surface but the wood rafters contain it. It doesn't take much heat differential, and I think it happens more with high humidity near freezing temperature. All of these responses are only opinion based on our own observations, but ask Canadians unless you get someone edumacated to do scientific-like experiments.

logman · April 26, 2010, 06:23:55 PM

The roof on my timber frame with sips in Md never looked like that. All the normal constructed homes would have the lines where the rafters are, but mine never had any lines except one small spot that I must have missed. I foamed mine like it showed in Ted Bensons book. Drilled holes after the panels were up and foamed the devil out of it. It would have been much easier foaming that channel prior to sliding the panels together.

frwinks · April 27, 2010, 10:13:34 AM

Quote from: witterbound on April 23, 2010, 10:43:25 AM
I helped a crew install panels on two houses about 4 years, so I'm no expert. But the panels we installed weren't designed to have any foam sprayed in the seams between the panels, I don't think. One panel had a 'groove' and the other panel had a 'tongue.' Foam rubber weatherstripping was installed on the 'grove' side, I think, then they were pulled tight together. Are these seams normally foamed when the sips are installed?

I'm no expert either, but from reading a lot of install manuals ie. Foard Panels, I would say that the two houses you mention would have similar issues to OP's house.

The point of spending the extra $$$ and prolly the only advantage of properly installed SIPS is to eliminate thermal bridging and build a tight house. Sure the OP's house might not have the bridges @ 16"OC like a stick framed roof, but there's still warm air getting out and condensing under those shingles. With that comes heat loss, mold and rot.

Jim_Rogers · April 27, 2010, 12:29:44 PM

Quote from: frwinks on April 27, 2010, 10:13:34 AM
but there's still warm air getting out and condensing under those shingles.

I don't know if you can say "warm air" is getting out. Warmth is getting out, but we don't know for sure if "air" is leaking out. Warmth leaking out is a thermal bridge and that could be why the roof has lines on it.

If he followed the vapor barrier instructions then no "air" should be leaking only the warmth is bridging.

In my opinion......

frwinks · April 27, 2010, 01:06:51 PM

looking at the pics, there's no VB under the sips and IMO it would be impossible to install one effectively once the sips are up. I thought with the super low perm rates of SIPS VB was optional (some inspectors want it, some don't).

Thehardway · April 28, 2010, 01:48:24 PM

Kettle,

Can you tell us what the weather conditions were when you took those pics? Is that just morning frost on the roof? SIPS can do some strange things. I had a couple scraps of SIPs laying on the ground at my place and some rubber over them. During the summer, the top of the rubber would have very heavy dew on it every morning. During the winter, snow that fell on the SIPS would never completely melt, it turned into ice and had to be chipped off.

If that is morning frost on the roof (which is what it looks like) it would only require a degree or two of temperature difference OR humidity to make that difference at the joints to. It may not be a heat leak, just a surface temp difference because of the different material thickness causing a delay in temp rise/fall. I'm not saying this is a good thing or normal, I just wouldn't panic.

It's like how frost will form on a windsheild in the middle but not around the edges. There is no heat on in the car, but the metal/rubber works as a thermal sink of sorts. How did it behave when there was actually 4-6" of snow? Did the snow melt faster at the seams?

Magicman · April 29, 2010, 01:57:59 PM

With zero air loss, how would you deal with the moisture buildup inside of the house? Here, we have to provide a vent arrangement to allow moisture to be expelled. Yes, you do then have some heat loss.

You want this air/moisture loss to be controlled by you and not by poor quality construction/design.

Thehardway · April 29, 2010, 02:15:12 PM

Magicman,

In a SIP house that is very airtight an ERV or HRV is used to expel indoor air and draw in outdoor air without losing the heat or cooling. It is a mechanical system. It not only helps control humidity but also IAQ.

You will probably see the old style vented roofs go the way of the dinosaur in the next 10-15 years. They are in the process of re-writing the code for vented roofs and crawlspaces especially in warm/humid zones due to mold issues.

kettleviewtimber · April 29, 2010, 05:31:35 PM

Thehardway,

You are correct. This is a morning frost. When there was 3 to 4 inches of snow there was no visible sign of melting at the seams. Maybe I would notice some melting at the seems when the air temperature would get above 32. The caulk that Pacemaker had us use I felt was inferior. It would get very hard and brittle with little to no gap filling qualities.
Does anyone no a way to check if I'm getting moisture buildup under the shingles or between the panels without ripping up the roof?