We just bought our first house 3 weeks ago. The house was constructed in 1980 and is a modified/blunted A-frame design where the A-frame portion is skinned in SIPs. I'm including two pictures from the original real estate listing as I haven't yet taken any pictures of my own. The house is sort of cross-shaped when viewed from above, with one axis being much shorter than the other.

The first picture shows the view looking at one of the short ends, with the long axis visible behind.


The second picture shows an interior view down the long axis of the house showing the repeated, widely spaced A-frames that support the SIPs.


Upon the pre-sale inspection of the house, we noticed that one of the short portions of the cross (the one in the picture actually) had a BIG sag in the roof and the inspector said it was so soft up there he didn't feel safe walking out to the center of the sagging area. A portion of the roof (not the one with the current problem) had been repaired in the past, according to the seller, so we called that same person for an estimate to repair this problem. We got a quote, negotiated a reduction in the cost of the house, and bought it. Since then, we've started the remodeling we wanted to do to the inside of the house and have found out that the original builder (we think the first homeowner, not a professional) was an absolute idiot and LOTS of things are wrong with the house. The roofer got the repair/replacement SIP delivered a few weeks ago, but we're on our 20th consecutive day of rain here, so it hasn't been installed. The longer I've sat here and looked at the SIP, the more concerned about the way this repair is going to be done (and by extension the way the past repair was done) I've become. The contractor says this small SIP panel sitting in my workshop is enough to repair the big spongy spot on the northeast roof as well as something else he saw on the southwest roof. The problem with that is that the SIP he ordered it tiny. It's perhaps 6x4 feet at most. There's no way he's replacing the entire panel up there. It's like he's planning on cutting a window in the existing SIP and patching this in somehow.

1) Is inserting a "cookie cutter" patch like this a valid way to repair a water-damaged SIP?

1a) What questions should I ask the contractor to find out if he knows what he's doing with SIPs or if he's just treating them as though they were a "normal" roof?

2) As far as I can tell, the construction of this house is the interior paneling (plywood with texture), the SIP, then tar paper, and finally shingles. From what little I've read, that's guaranteed to cause problems, right? This would certainly be backed up by the fact that there have been multiple roof failures since 1980.

3) All the SIP manufacturers, in their FAQ about repairing SIPs, say a Structural Engineer must be consulted. Is this true? If so, how do I go about finding a Structural Engineer that knows what they're doing with SIPs?


We're at our wit's end here, I'm not sleeping well anymore and my wife is getting sick every time she eats. It's our first house and we were so happy to get out of my family's basement but now we're terrified we're looking at 10s of thousands of dollars we have no way to come up with just to get this place safe to live in.

Posted By williaty on 10 Jul 2013 11:19 PM
We just bought our first house 3 weeks ago. The house was constructed in 1980 and is a modified/blunted A-frame design where the A-frame portion is skinned in SIPs. I'm including two pictures from the original real estate listing as I haven't yet taken any pictures of my own. The house is sort of cross-shaped when viewed from above, with one axis being much shorter than the other.

The first picture shows the view looking at one of the short ends, with the long axis visible behind.


The second picture shows an interior view down the long axis of the house showing the repeated, widely spaced A-frames that support the SIPs.


Upon the pre-sale inspection of the house, we noticed that one of the short portions of the cross (the one in the picture actually) had a BIG sag in the roof and the inspector said it was so soft up there he didn't feel safe walking out to the center of the sagging area. A portion of the roof (not the one with the current problem) had been repaired in the past, according to the seller, so we called that same person for an estimate to repair this problem. We got a quote, negotiated a reduction in the cost of the house, and bought it. Since then, we've started the remodeling we wanted to do to the inside of the house and have found out that the original builder (we think the first homeowner, not a professional) was an absolute idiot and LOTS of things are wrong with the house. The roofer got the repair/replacement SIP delivered a few weeks ago, but we're on our 20th consecutive day of rain here, so it hasn't been installed. The longer I've sat here and looked at the SIP, the more concerned about the way this repair is going to be done (and by extension the way the past repair was done) I've become. The contractor says this small SIP panel sitting in my workshop is enough to repair the big spongy spot on the northeast roof as well as something else he saw on the southwest roof. The problem with that is that the SIP he ordered it tiny. It's perhaps 6x4 feet at most. There's no way he's replacing the entire panel up there. It's like he's planning on cutting a window in the existing SIP and patching this in somehow.

1) Is inserting a "cookie cutter" patch like this a valid way to repair a water-damaged SIP?

1a) What questions should I ask the contractor to find out if he knows what he's doing with SIPs or if he's just treating them as though they were a "normal" roof?

2) As far as I can tell, the construction of this house is the interior paneling (plywood with texture), the SIP, then tar paper, and finally shingles. From what little I've read, that's guaranteed to cause problems, right? This would certainly be backed up by the fact that there have been multiple roof failures since 1980.

3) All the SIP manufacturers, in their FAQ about repairing SIPs, say a Structural Engineer must be consulted. Is this true? If so, how do I go about finding a Structural Engineer that knows what they're doing with SIPs?


We're at our wit's end here, I'm not sleeping well anymore and my wife is getting sick every time she eats. It's our first house and we were so happy to get out of my family's basement but now we're terrified we're looking at 10s of thousands of dollars we have no way to come up with just to get this place safe to live in.

williaty,
1.No a small patch will not suffice

1.a you should ask for the engineered plan and building permit,this inspector/contractor is negligent in not investigating the proper repair method before you purchased the house, you probably did not negotiate enough to do the repair the right way
2. The construction method is fine,but if you are in a colder climate and the SIP was not sealed properly at the spline joint , this is problematic,
3.Hindsight is 20-20, the engineer should have been consulted prior to the purchase ( especially by the home inspector) If you let me know what state you are in, I will see if I can connect you with a licensed PE
I would put the brakes on this repair until you get engineering advice, the contractor may cause additional structural damage if he is not qualified, this is no typical roof repair

I would make it clear that you aren't looking for just a repair of the bad spot, you want a complete fix so that the problem won't occur elsewhere on the roof.

Repairing a SIP is not like repairing a piece of OSB/plywood. Two totally different products. A SIP is like a structural "I Beam". You simply don't just start cutting into it and patching it. As Chris recommended, it's time for a qualified PE.

Well, I'd forgotten about this thread and somehow I didn't have email notification enabled.

We did eventually decide to contact a structural engineer. It was a hassle, but we found one in our area that has previous experience designing with SIPs. Most of the engineers we talked to had heard of them but never worked with them. We're having problems getting scheduled to actually come out though. The roofer is not pleased with us for causing a delay and has said that waiting for the engineer to come look at it will put us at the back of the line again, so our ability to move in has already slipped by at least a month.

The engineer asked for some pictures of the affected area. When I started snapping away, I realized 3 bad things. 1) The interior ceiling under the soft spot isn't parallel to the exterior roof line in that area meaning that the surface I can touch inside the house isn't the SIP that makes up the roof 2) the interior surface I can touch IS a SIP and 3) that SIP isn't flat anymore and the seam between it and the wall SIP has styrofoam beads falling out of it when the trim was removed. I'm afraid that the ceiling in the dormer was sealed up against the SIPs that make up the roof line, creating a sort of triangular area with no venting through it that might have been collecting water from the roof leak.

However, it needs to be right before we move in. My wife and I are just terrified we're going to hear that the original construction was faulty or the water damage is pervasive and all the SIPs need replaced. There's no what we could afford to do that and we'd end up having to sell the property for the value of the land and take at least an 80% loss on it.

What people didn't take into consideration with OSB SIPs is that they are like any wood assembly they need to be vented on the outside to insure that they dry out when they get wet. The other thing that people didn't understand is that where the 2 SIP panels met, it created a pathway for condensation to form, overtime this created moisture problems and inevitable rot.

The Building Science industry has studied and discussed the above problems and provided solutions. One is to furr the outside of the roof and wall assembly to allow the SIPS to vent and dry out. The other is to create a recessed spline where the 2 SIPs meet to prevent a cold spot for condensation to form. Sadly, the wood SIP community has NOT embraced these principles completely and continues to build homes without these provisions.

Building Science - SIP moisture issue

In the end you are in a bad predicament. Only the engineer can determine how bad it will be. The cost to furr out the SIP on the exterior is beyond what your budget will allow. You can either live with it the way it is or try and fix it which will get very costly. The sad part is that it costs 3-4 times more to fix a job than it did to do it right in the first place.

Wait for the engineer results and post what he recommends. That is the only option right now.

You can try and sue the former homeowner. If they knew about this problem and chose not to disclose it, that might be grounds for a lawsuit depending on your state and home buyer protection laws.

When Engineer Joe Lstiburek (Building Science Corp., Westfield, MA) was asked by the Structural Insulated Panel Association (SIPA) to investigate SIP issues he concluded that, “The industry is in denial,” said Lstiburek. Premier SIPs blamed the SIP problems on poor assembly techniques. When the roofs were inspected they were told, “Our roof has been declared in danger of imminent collapse.”

I encourage you to read this 15 page article on SIP rot, the investigation, the determination, and the final resolution:

1. A properly installed vapor retarder (0.10 perms or less) on the warm side of the SIP.

2. Roof sealing procedures are described to achieve tight construction. Proper sealants are to be installed on dry surfaces. Voids in
the panels are to be filled with sealants. Manufacturers directions are to be carefully followed. Etc.
 
3. SIP roof systems should be covered with a cold roof, including not less than a 1.5-inch air space above the top skin of the panel.

Yet when you contact Premier SIPs or other large OSB SIP manufacturers, the installers continue to deny that a cold roof is needed. The reason for their denial is that the costs of SIPs goes up when you take into account that you now have to install a cold roof, a vapor retarder, and proper sealing that is more labor $$$ intensive.

The first listed solution is something you could easily implement to reduce future damage. Reverse the pressure if the A/C is on.

1) Changing the air pressure. Instead of allowing warm air to rise up into the ceiling through
penetrations, cracks and gaps, you put the house under slight negative pressure...

Here is a good resource tool for building with SIPS:

Builders Guide to SIPS For All Climates  or Here