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OSB lap siding - brand new house


CheckItOut
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Hi,

If it's installed correctly, there probably won't be any issues - at least not within the warranty period. The new composite sidings use more wax and borate is mixed in with the formulation to make them more resistant to rot. I'd be more concerned with the way it's installed, because there are very specific installation rules that most contractors seem to ignore.

ONE TEAM - ONE FIGHT!!!

Mike

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Originally posted by CheckItOut

OSB lap siding on a brand new home here in NC. House was listed as fiber cement but I looked a little closer. I did a web search and it seems that this material has the same issues that hardboard does. Is that correct?

Is this material becoming popular in new construction?

Um, it's been popular in new construction for about 20 years. If it's installed even close to the way it's supposed to be installed, it should be fine for at least a couple of decades.

The pre-96 osb siding is another story.

- Jim Katen, Oregon

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Um, it's been popular in new construction for about 20 years. If it's installed even close to the way it's supposed to be installed, it should be fine for at least a couple of decades.

The pre-96 osb siding is another story.

- Jim Katen, Oregon

We don't see it here - just hardboard and fiber cement- in terms of lap-type siding

I installed inage resizer - thanks for the tip.

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Originally posted by CheckItOut

I'll try the pic again...

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It's hard to tell from the picture, but it looks like a vinyl window with its fin installed on the outside of the panel siding and with thin trim applied over the fin. Is that right? If so, it's screwed.

- Jim Katen, Oregon

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Originally posted by Jim Katen

Originally posted by CheckItOut

I'll try the pic again...

Image Insert:

2008111205226_11108020.jpg

50.94 KB

It's hard to tell from the picture, but it looks like a vinyl window with its fin installed on the outside of the panel siding and with thin trim applied over the fin. Is that right? If so, it's screwed.

- Jim Katen, Oregon

No. There is no trim. What you see on the top horizontal edge of the window that meets the siding is just the vinyl window. Once the caulk gives way, water will go behind the siding.

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Originally posted by CheckItOut

No. There is no trim. What you see on the top horizontal edge of the window that meets the siding is just the vinyl window. Once the caulk gives way, water will go behind the siding.

In that case, isn't there a nailing fin on the window that's behind the panel siding?

Some window manufacturer's actually say that flashing isn't required in this type of installation. The nailing fin essentially acts as flashing.

- Jim Katen, Oregon

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Originally posted by Jim Katen

Originally posted by CheckItOut

No. There is no trim. What you see on the top horizontal edge of the window that meets the siding is just the vinyl window. Once the caulk gives way, water will go behind the siding.

In that case, isn't there a nailing fin on the window that's behind the panel siding?

Some window manufacturer's actually say that flashing isn't required in this type of installation. The nailing fin essentially acts as flashing.

- Jim Katen, Oregon

Yes, there probably is a nailing fin back there. The drip caps though are slightly angled away from the house to direct water away from the siding. Maybe this is a best practice issue as opposed to a requirement.

Thanks a lot for your help!

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Hi,

It's a best practice issue. With the advent of nailing fins, a lot of builders got away from using drip caps. Now they use self-adhering bituthene flashings beneath the siding and caulk the perimeter of the vinyl windows; the caulk supposedly being a secondary obstacle to infiltration. The problem, for us anyway, is that we have no way to know whether they applied those self-adhering flashings correctly and in the proper sequence behind the siding.

One thing they do a lot here is only use the bituthene at the bottom and at the sides of the window and then they simply bring the building paper down over the flange on the top side of the window and rely on that vinyl nailing fin, the 2 inch overlap of the building paper, and the caulk, to prevent infiltration at the top of the window. It saves the builder about 30% on the cost of bituthene per house and it's really kind of a dumb move because you can't rely on homeowners to reliably check that caulk bead along the top of a window and ensure that it remains intact. Vinyl windows expand and contract at twice the rate of aluminum, wood, and fiberglass windows, so there's a good likelihood that, with that constant movement, the bead will fail and they'll get infiltration if the window is on the weather side of the house. However, again, unless I get into the development early enough to see that is how they've done it, there's no way that I can know whether they used that technique or not.

A question - that siding can be used as structural sheathing with nothing more behind it than a moisture resistant barrier. Do you know if they used additional structural sheathing behind it, 'cuz, if they didn't, there's no way they could have flashed it with bituthene, in which case the only thing keeping the water out will be the caulk, as you fear.

By the way, after a long hiatus, a lot of siding guys around here have figured out that it would be a good idea to start using drip caps again and we're seeing them on new construction more frequently now than we did, say, 5-6 years ago.

ONE TEAM - ONE FIGHT!!!

Mike

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I'm willing to bet Mike O's Nordic-Trac that that's a leaker. Even if the windows are flashed properly, the connection between the brick mould head trim and the siding is just caulk. The pic shows the first floor windows. I'm guessing the caulk job at the top of the 2nd story windows is spotty, at best. Water will find a way in, and then it's just matter of time...

I'd also be willing to bet that the shutters were installed before they caulked, which means that there's a nice, long, hidden crack for moisture to hang out.

$50 worth of metal drip edge would have made all the difference in the world.

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In the development where I live they built most of the homes with unfinished rooms upstairs. Most of homes are sided with LP panel and have vinyl windows. No house wrap, nothing.

Every unfinished room I have ever seen including my own leaks.

It's stupid but oregon code allows it. A few years back the APA started recommending weather resistive barriers for panel siding.

Take a look at ASTM E2112. They recommend at least running a weather resistive barrier top to bottom where windows are located.

Chris, Oregon

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Originally posted by Home Pride

Originally posted by CheckItOut

OSB lap siding on a brand new home here in NC. House was listed as fiber cement but I looked a little closer. I did a web search and it seems that this material has the same issues that hardboard does. Is that correct?

FYI, that photo isn't lap siding.

It's only a guess, but it's probably lap siding at the street-exposed side and panel siding on the sides and back and that's how he made his mistake. At least that's the way about 90% of the builders around here do it.

OT - OF!!!

M.

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Originally posted by hausdok

Originally posted by Home Pride

Originally posted by CheckItOut

OSB lap siding on a brand new home here in NC. House was listed as fiber cement but I looked a little closer. I did a web search and it seems that this material has the same issues that hardboard does. Is that correct?

FYI, that photo isn't lap siding.

It's only a guess, but it's probably lap siding at the street-exposed side and panel siding on the sides and back and that's how he made his mistake. At least that's the way about 90% of the builders around here do it.

OT - OF!!!

M.

You are kind of right. The house is a mixture of lab and panel. An odd mix. The photo though, is not of the lapped portions.

Good info above on the bituthene - thanks.

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Originally posted by Garet

Starting with the '03 IRC, flashing is required above all wood trim that projects out from the wall.

Garet

Jamison, the original poster, says that there is no wood trim here. Just the vinyl window with no trim around it.

The requirement for flashing above projecting wood trim is much older than '03. It's in 703.8 back to 1995 CABO. Before that it was in 503.8 back as far as 1979. I seem to recall that it's in the '76 CABO as well, but I can't lay my hands on that book right now.

- Jim in Oregon

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Originally posted by chrisprickett

The trim is wood (or some type of composite) brick mould. No doubt about it.

Well it looks like brickmold to me too, but Jamison says it's just the vinyl window. Maybe there's a window manufcturer in NC that makes vinyl windows with a look-alike brickmold trim built in?

-Jim Katen, Oregon

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