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I inspected a house with blue foam sheathing panels. There is a piece of flashing that is sandwiched between the siding and foam and wraps down beneath the sheathing (so you can only see the foam at foundation level if you bend out the flashing). The foam only extends down to the TOP of the sill plate. I am having trouble finding specific standards for installation this foam sheathing, but shouldn't the sheathing run down below the bottom edge of the sill plate to ensure water that gets behind the siding sheds away from the sill plate/ framing? I checked a couple other homes in the neighborhood and this installation is the same throughout (subdivision built in 2000). Any help would be appreciated.

P.S. - there is no visible wall sheathing or housewrap on this application

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Hi Brandon,

Did you take any pictures? Even if you don't use photos in your reports, it's a good idea to take pictures of anomalies like that so that you can post them here. It'll give us a better idea of what your describing.

I don't think I've ever seen such an arrangement. What type of siding did it have?

OT - OF!!!

M.

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Originally posted by Brandon Whitmore

I inspected a house with blue foam sheathing panels. There is a piece of flashing that is sandwiched between the siding and foam and wraps down beneath the sheathing (so you can only see the foam at foundation level if you bend out the flashing). The foam only extends down to the TOP of the sill plate. I am having trouble finding specific standards for installation this foam sheathing, but shouldn't the sheathing run down below the bottom edge of the sill plate to ensure water that gets behind the siding sheds away from the sill plate/ framing?

That makes some sense, but I'm not aware of any general rules regarding how far the foam has to extend. If there's going to be a rule, it'll be related to the type of siding.

I checked a couple other homes in the neighborhood and this installation is the same throughout (subdivision built in 2000). Any help would be appreciated.

P.S. - there is no visible wall sheathing or housewrap on this application

I'll bet that there's structural panel sheathing at the corners and maybe one or two other places as well in order to comply with the brace panel requirements in 602.10.

I've seen Legend build this way. Was it them?

- Jim Katen, Oregon

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Mike,

I could not get any pictures of this issue because of the lack of access to the area-- wish I could have. Siding was Hardi lap

Jim,

You are amazingly correct- it was Legend Homes that built the homes and it was Legend Homes that installed the engineered wood floor on the particle board in my last post.

I went onto some manufacturers websites trying to get some information on specific requirements. At least one of the websites specified that you should ensure you use a long enough piece of foam to completely cover the sill plate.

My concern is that water getting behind the Hardi lap siding will drain down onto the sill plate, etc.

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Originally posted by Brandon Whitmore

. . . My concern is that water getting behind the Hardi lap siding will drain down onto the sill plate, etc.

There's supposed to be building paper behind the hardiplank. That's what forms the secondary drainage plane, not the surface of the sheathing. Was there building paper and did it extend past the sill?

- Jim Katen, Oregon

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Originally posted by Brandon Whitmore

Jim,

No building paper visible behind the siding on any homes checked.

I am not finding anything that specifically requires building paper to be used along with the foam. The IRC does not cover any of this and I believe the foam can be used as a WRB (not best practices though).

Am I missing something?

In the Oregon Residential Specialty Code, look at table R703.4. At the bottom of the table, it says that fiber cement lap siding requires sheathing paper.

There is a note (note y) that refers you to the exceptions in R703.2. None of those exceptions applies to fiber cement siding. However, in the body of R703.2 it mentions that you can substitute an "other approved weather-resistant material." I suspect that someone considers the foam to be a weather resistant material.

However, there've got to be plywood or OSB panels at the corners. *They've* got to be covered with building paper.

- Jim Katen, Oregon

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  • 7 months later...

I had a similar inspection a few years back - also Legend. I called Wa County and Portland and was told that no VB was required but seams had to be taped (sealed). Hardi requires nails to be 1 1/4" plus the thickness of the foam (called "blue poly" bu the Super) and they be nailed to the framing wall studs. In the crawl I removed a few sections of foundation pony wall insulation and noticed a nomber of siding nails had missed the studs (more than 1 stud) so I pushed the siding off with my foot - you know, so the Super and buyer could see it from the exterior. He was upset but did a good repair. My concern was how many nails missed further up the wall since this is a high? Only time will tell. Funny thing though, buyer was either a civil or mechanical engineer and it did not bother her at all.

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