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Vinyl Siding over LP Lap Siding


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I just looked at a house in Bellingham, Wa where there was Vinyl siding installed directly over the LP Lap siding. I know this is not the best idea espicially since the vinyl siding was not installed properly and was allowing water back behind the siding. What I was wondering about was the fact that the LP lap siding had no sheathing back behind it. The hosue was built in 1994 and was 2x4 construction. So my question is, can LP Lap siding be used as shear strength?? Things that make you go Hmm[:-monkeyd

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There's alternatives to sheathing as a provider of shear strength. Steel diagonal bands or 1X4 'let-in' to the studding. I wouldn't consider the lap siding as contributing anything to shear strength.

It would be very odd in my area to find a 94' structure without exterior wall sheathing, but then I live in a 110 mph wind zone.

Marc

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The entire wall need not be sheathed to achieve the necessary shear strength. Nowadays, we use 'brace panels'. In 1994, as I recall, there were rules that governed the specific placement and percentage of the wall that needed to be reinforced to achieve the necessary lateral strength.

Bottom line, just because you can't see the sheathing in the places where you look doesn't necessarily mean that the structure is defective.

Were you concluding that the sheathing was absent based on looking at it from the attic - at a gable end perhaps?

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No, I could see there was no sheathing down by the crawl space entrance. The entrance was through the wall on the exterior. I could see all layers. 2x4 stud walls, house wrap, LP Lap siding, and then the new Vinyl siding over that.

If diagonal steel bands or 1X4s are installed, you wouldn't be able to see them from that cross sectional view.

Marc

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No, I could see there was no sheathing down by the crawl space entrance. The entrance was through the wall on the exterior. I could see all layers. 2x4 stud walls, house wrap, LP Lap siding, and then the new Vinyl siding over that.

L-P allows their lap siding to be nailed directly to studs as long as there is a weather resistant barrier between the siding and the studs as you've described. As Jim has said, brace panels would still be required at a cripple wall even though most of it might be lap siding nailed directly to the studs with nothing but wrap between the studs and the siding.

You did check to ensure there was a WRB between that old L-P and that vinyl siding and you did go inside and traverse that entire crawlspace to verify there weren't any brace panels in place, and to inspect all of the other things you can't see from the hatch, right?

ONE TEAM - ONE FIGHT!!!

Mike

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Yes I did and no there wasn't a WRB between the vinyl and LP. NO other structural panels either. Builder was from Canada. Built 4 houses in this neighborhood and left never to be found again. Buyers ended up walking away.

Good job!

Guess those houses will end up being an interesting experiment to see how long that stuff will function adequately as cripple wall bracing. Should be interesting the next time we have a significant quake.

ONE TEAM - ONE FIGHT!!!

Mike

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