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Crusty:
I think that by caulking the sheathing and applying housewrap you will be creating a double vapor retarder which will tend to trap liquid moisture within the wall.
If you do go with this configuration and the wet spray cells, be sure that the wall assemblies are very dry after the cells but before the drywall is installed.
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I recently did a job on the Atlantic coast where I used grey butal sealent on the sheathing joints. As we set the sheathing, the piece in place was caulked and each sheet set into the butal with the excess wiped clean. We also applied Vycor membrane over the nailing flanges of the windows (Anderson) extending past the additional casing line. Then installed the Tyveck, tape and flashing as usual. Too tight ? Maybe, but it won't leak !
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Don't caulk, for the double vapor barrier reason. The glues in plywood act like a vapor barrier to some degree. You want to keep water from getting in, not getting out. Use type "D" tar paper. In the long haul it will out perform all the other kinds of house wrap.
Steve
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Crusty, unless you live in a very arid area, the plywood needs to be gapped. The stamp on the plywood probably reads "sized for spacing" which is intended to allow for a gap between panels, due to the fact that plywood expands and contracts with moisture and temperature. Here in Oregon I've been on jobs where plywood has been butted tight, and the following day its buckled out 1-2" inches between studs. And thats at 16" centers... I've got the pics to prove it. Wrap the house with building paper, use a good rubberized flashing like EZ Seal, BT20, Blueskin, or the Grace product around all your windows(especially if they are Vinyl, it contracts and expands more than wood), and make sure your siders do a great job caulking, and you can rest easy.
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When my framer put up the 1/2" 4-ply exterior sheathing, he left gaps all around for expansion (it was 108 F here today - hottest spot in the nation). He said that's normal and usually it's just left that way and the housewrap keeps the air from blowing through. I suspect he's right in that it's probably "normal" for this area. Most builders here think a house needs to "breath," that it shouldn't be too tight. My approach is to make it as tight as possible, and I'll control the air changes via the HVAC system where I can regulate it and filter it.
Am I nuts for thinking that I want to caulk all the cracks with siliconized acrylic? Is that overkill? I intend to have the walls blown with modified cellulose (has a water-activated binder, blown in with a fine mist)which should give a pretty good seal. And yes, I'll use the housewrap if only to protect the sheathing until the siding is installed.
*Testing the e-mail notification feature.
*I don't know about caulk, but I do know some builders who tape those joints with housewrap tape. I'd do that, then use #15 tarpaper.Andy
*Second Guessing tradesmen is supposed to be done before you hire them right?....How wide are the gaps...1/8"?...If more, then he is covering up ineptitude...Caulk....I have been required to use it on siding work but I prefer to use as little cauld as possible...I would not after the fact caulk a frame. You don't need the redundancey...Your housewrap and cells will do nicely...What is working where you live?...It's very expensive to discuss every day's work and second guess...and irritating as hell for those you are doing this to...Do your homework quick for all the rest of this project and read "How to win friends and influence people (bring coffee daily when you arrive at ten, smile, then get out of the way...Meetings are for non work time and not every hour.near the stream,ajCrusty...don't take of this too personally...there's just too much blame game and not enough homework and trust being posted at bitchtime...
*I wouldn't caulk.Sounds like alot of work and I'll just tar paper the thing anyway.Tarpaper outside, insulation and vapor barrier inside. Those expansion gaps are gonna be fine. We're not talking about really big gaps are we?
*AJ, I don't consider myself to be "second guessing." Building practices are regional and much of what is done anywhere is tradition, or done simply because the builder has never heard of a better way.For example, I have NEVER seen felt used as a housewrap in Arkansas, though many of you seem to do it regularly, and it seems to make better sense. If I asked my framer to do that, it would certainly be considered and "extra" ($$) because it's much more time consuming than housewrap, and "no one does that around here." And a vapor barrier is never installed on the interior of the house in our area which is "mixed/humid" (I think). On the other hand, 99% of the "upscale" houses here use brick and/or VINYL siding. Ocassionally you'll see masonite. I've never seen hardiplank used here, and haven't seen wood siding (except an occassional cedar) in 20 years. Probably 90% of the new houses here (including the BIG ones) get builder grade vinyl windows.Most of you guys are probably ill by now (vinyl!?!?.... uuurrrghhh) but "thats the way it's done" here. I guess my post was aimed at trying to find out how things are done elsewhere, where perhaps builders are a little more enlightened.Anyway, since I'm paying for it, and I'm doing the work, I'm caulking (unless there is a "building science" reason not to). You can't make a house "tight" after the fact.I try to be helpful when I'm around (carrying material, handing up trusses), I've supplied them ice cold watermellon, cantaloupe, Gatorade. I loaned them my industrial strength fiberglass ladders because the rickety wooden ones they have scare me to death. I bought them a big fan. I'm basically a nice guy and I try to treat people right. But it's MY money, and if I hurt their feelings by daring to question their knowledge, well hey, they're getting paid well enough that they'll get over it. If I screw it up, I have to live with it -- not them. On the other hand, it they screw it up, I still have to live with it. :)
*Crusty:I think that by caulking the sheathing and applying housewrap you will be creating a double vapor retarder which will tend to trap liquid moisture within the wall.If you do go with this configuration and the wet spray cells, be sure that the wall assemblies are very dry after the cells but before the drywall is installed.
*You are using the HVAC to let you breath, create a few drafts in the framing to let the walls breath. I for one don't want to live in a plastic bag, and these houses are too damn tight these days. Air them out a little, let them breath. I quit using tyvek for that reason. And as for the gaps, well, if it's nailed off tight to the stud, and you run it vertical, where is the air gonna go? Keith C
*Double vapor retarder..... let the walls breath... I really hadn't thought about it from that perspective. Perhaps from a building science point of view (as opposed to pure thermal efficiency) it would be a good idea to let out any moisture that happens to get in the wall (though hopefully none will).