View Full Version : Sealant on T1-11 siding

Bill Anglin
10-23-2016, 07:31 PM
This is a condition that I find myself writing up all the time on new construction. Applying sealant at top of trim board that covers horizontal joints between T1-11 siding. The seller of this house has asked the builder to install the sealant that was called out in my report. The seller claims that by installing the sealant will void the manufacturers warranty. Can some of you other inspectors give some insight into this subject that I can share with the buyer? Thank you in advance for your help.

Jerry Peck
10-23-2016, 08:10 PM
First, a question: Is there a 'Z' flashing between the lower T-1-11 panel and the upper T-1-11 panel?

Likely answer: No.

Because if there was, no trim would be needed or used.

A second question: Is there a 'Z' flashing at the top of the wood trim? (I'm looking on my phone and suspect that the photos were taken looking up at the bottom of the trim.)

No need to seal the bottom, and don't really want to seal the bottom.

Bill Anglin
10-23-2016, 08:43 PM
I cant tell if there is Z flashing behind the trim without removal. I'm with you though, if it were there, they probably wouldn't install the trim. There is not flashing on the top side of the trim. I looked up LP Smart Side installation instructions and it says to apply sealant at all gaps and separations. I cant see how applying sealant would void the warranty. Doesn't make sense. More likely to cause deterioration behind the trim without sealant.

Gunnar Alquist
10-23-2016, 09:06 PM
I see this all the time. In my experience, the panels are generally properly flashed, but the contractor or carpenter wants to install a "belly band" to cover the unsightly z-bar. The problem, as you have surmised, is that water gets down between the trim and siding and damages the siding. If trim is used, the z-bar should extend over the top of the trim. Rarely done. Caulking can help, but it will fail and require regular recaulking before it wears out. Only be on the top edge should be caulked, in case water does bypass the trim.

Bill Anglin
10-23-2016, 09:32 PM
Thank you for your responses. Has anyone heard that applying sealant will void the siding warranty?

Jerry Peck
10-24-2016, 05:38 AM
Thank you for your responses. Has anyone heard that applying sealant will void the siding warranty?

I would send an email to LP with that question - that will give an answer in writing.

Garry Sorrells
10-24-2016, 05:42 PM
T......The seller of this house has asked the builder ....The seller claims that by installing the sealant will void the manufacturers warranty. ....................

The statements are a bit confusing. Who is asking whom for what? Not that it really matters.

Is it LP, plywood or OSB? What manufacture?? Not that it really matters. If it doesn't have a Z flashing on horizontal edge it is wrong. Sealing T1-11 voids warranty, have them prove it.

Caulking the trim piece extends it's life. Though it will be the first to be replaced.

Jerry Peck
10-24-2016, 07:30 PM
Here's the nitty gritty I was trying to avoid having to post:
- From the IRC: (underlining is mine)
- - R703.1 General. - - - Exterior walls shall provide the building with a weather-resistant exterior wall envelope. The exterior wall envelope shall include flashing as described in Section R703.4.
- - - - Exception: Log walls designed and constructed in accordance with the provisions of ICC 400.

- - R703.4 Flashing.
- - - 4. Continuously above all projecting wood trim.
- - - - (Jerry's comment: No ifs, ands, or buts ... "continuously" and "above all" ... "projecting wood trim".)

- - R703.5.2 Panel siding.
- - - (blah, blah, blah - first paragraph - too much to type that does not apply to the discussion)
- - - Joints in wood, hardboard, or wood structural panel siding shall be made as follows unless otherwise approved. Vertical joints blah, blah, blah. Horizontal joints in panel siding shall be lapped not less than 1 inch (24 mm) or shall be shiplapped or flashed with Z-flashing and occur over solid blocking, wood or wood structural panel sheathing.
- - - - (Jerry's comment: "and occur over solid blocking, wood, or wood structural panel sheathing" - if T-1-11 is used, there may not be any structural panel sheathing behind it, which means that the horizontal joints shall be over solid blocking, not just "air space" between studs.)

Thus, as I was trying to point out previously, not only does the T-1-11 panel siding need to have that Z-flashing, there also needs to be a Z-flashing over the top of that trim ... which means - why would you need to seal it?