Sheathing rot closed cell foam newer construction
I am writing seeking ideas and advice:
We are dealing with rotten, soaked sheathing on a home that was finished in 2014. Rusty nails and a couple small gaps were noted in siding which led us to pull the siding away. We found extensive rotten sheathing just about everywhere. And the sheathing was wet…like touch it and your fingers are wet like you dipped them in water wet.
The house is on a lake in CT. The exterior siding was Boral true exterior vertical V-groove siding. House wrap is benjamin obdyke hydrogap. 1/2″ CDX ply for sheathing, and then closed cell spray foam in between 2×6 stud bays. The sheathing is diffusely rotten, and in areas which are not close to anywhere where water intrusion was suspected.
Anyone have any ideas? Could the hydrogap be creating an air pocket which is leading to condensation? There’s really a tremendous amount of rot considering how new the structure is. Siding was in good shape, installed well, with a few gaps that had opened at some butt joints but nothing crazy. Otherwise is this a spray foam issue? Any ideas, questions, input are appreciated
Mike
Replies
Yowch
Can you post a couple more pictures showing more height and width. It’ll help see what’s above and around that shot.
Thanks.
Just a hypothesis that the sheathing is condensing on the inside of the wall. Up against the foam with no way to inward dry due to the foam stopping vapor movement it becomes waterlogged. I think you need to look into how walls get condensation, and look into the "perfect wall." That has insulation on the outside of the sheathing the the back of it doesn't condense.
Several thoughts:
First, 2014 is less than 10 years ago. Does the builder know about this and did they provide a 10 year workmanship warranty?
If not, I would:
1. Contact Boral TruExterior siding. They list their products as practically waterproof.
2. Contact Benjamin Obdyke technical support with your detailed description.
3. Contact a spray foam company for advice.
4. Cut out some spray foam and test it for permeability. How is it supposed to perform and how does it actually perform. If applied incorrectly, or the wrong version was used, five to six inches of foam may be different than 2 to 3 inches of foam, regardless of whether it is closed cell or open cell.
5. Photograph how the siding and components were assembled. Include a ruler and notes in the photos. Verify that the siding was Boral TruExterior or what ever you believe it is.
6. What does the interior wall look like? Was the spray foam applied from the exterior
or interior?
6a. Is there a second vapor barrier in the wall (behind the sheetrock.)
7. What does the assembly at the top and the bottom of the exterior wall look like? Was it supposed to be able to vent at the top and drain at the bottom (assuming it was designed to vent and drain.)
8. What is the condition of the studs? In the photo the horizontal beam looks like it is perfect, but the vertical components, including the pattern of the stains on two or three different parts of the sheathing, do not look like a random pattern. Perhaps from the inside of the house you can see something that would explain the patterns on the exterior.
9. Find a professional architect, consultant, etc, that can do this for you or better, knows what has happened, and can fix it.
I cannot tell if there is a gap between the siding and the Benj. Obdyke Hydrogap. I did a siding renovation several years ago and created a gap between the siding and the sheathing (reverse board and batten), but there the comparison ends, because I didn't use spray foam, and the siding is wood, not a water proof non-natural material like Hardie plank or vinyl, etc.
In the south, we have humidity issues that require a different vapor barrier design than low humidity, colder environments require. So be cautious of internet advise and research. Very rarely do people qualify their opinions or experiences with their location or environmental conditions.
Please post your findings as this issue is working out to be as big as the Stucco issues of the late 20th century.
Hello,
Appreciate your response and the organized steps that are included. When I initially made this post, I was frantic as we had just discovered all the rot unexpectedly that day. I have since had some time to gather my thoughts and make an initial plan for a response.
The home was a custom build home according to a spec book which was written by our architect. I have since been in touch with the architect. Included in the specs were instructions for the installation of the benjamin obdyke hydrogap and of the boral siding. I would have a tough time morally trying to get the builder to somehow cover or warranty this as he and the finish carpenter/siding sub followed "our" specifications as they were written.
At the time that the house was built, the benjamin obdyke hydrogap was specified in the Boral literature as the proper WRB under their siding, and I really don't recall any mention of a rainscreen.
We have to do more research as to whether this is all over this part of the house, all over the whole house, etc, to better determine the scope of the problem. It's clear that water is getting stuck behind the siding and cannot get out. Whether this is secondary to condensation or rain and/or wind driven rain entering the wall assembly is unclear.
The plan at present is for our carpenter to replace the siding more or less as it is until we can full study the situation and react accordingly. Getting a building envelope specialist and getting in touch with and the opinions of the technical service people will take time.
Thank you for outlining the steps and for your opinion.
Will keep everyone posted.