Wall construction questions — stucco
我们正在阿什维尔NC，气候区4A，2,600'海拔地区建造一所房子。我读过许多关于灰泥和墙壁建筑的GBA文章 - 所有好东西。我们的房子里有灰泥外墙，至少有3'突出，我们正在考虑以下墙面建设：
• Drywall
• Intelligent membrane (do we need one)?
•2“x 6”螺柱托架充满矿物羊毛或纤维素吹
• Huber 1-1/2” Zip R Sheathing
• Benjamin Obdyke 10 mm Rain Slicker
•水电阻蒸汽渗透屏障(which is best)?
• Stucco Lathe
•硬涂层灰泥
We have three questions on the wall details which I hope you can answer for us:
1）我们是否需要在该墙体结构的内部下方干墙下方的智能膜？
2）我们应该用什么用于防水气相渗透屏障？
3) Is it wise to apply a self-adhering membrane under the weep screed, bridging the gap between the Zip R Sheathing and the concrete foundation?
Thanks in advance!
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Replies
With the ZIP-R sheathing properly installed you won't need the "Water resistive vapor permeable barrier", since ZIP uses a factory installed high quality spray on weather barrier.
It's not clear that Rain Slicker is needed or even desirable under the stucco lath. An air space would be good enough. There are stucco-specific permeable underlayments used in commercial construction that may be more appropriate, but all will wick more moisture and impede drying air flows more than a decent air gap. Installing 1x furring and mounting metal lath for the stucco on the furring is probably the best bet. That's a 19mm nominal gap, but with the variable flex of the lathe and the scratch coat squeezed through it'll be on the order of 10-12 mm air over much of it. Air is a much better capillary break than any mesh product!
A zone 4A climate doesn't need a smart vapor retarder on the interior, just reasonably air tight drywall with standard latex paint is fine.
My stand-by wall assembly is:
• Drywall
• 2x6 studs @ 24” o.c. filled with dense packed cellulose (You don’t need intelligent membrane)
• Regular taped Plwd/OSB + 1” taped polyiso (cheaper than Zip-R with 1” foam). Your foam if taped with approved tape is a moisture barrier.
• (Good) StuccoWrap and 60 JumboTex or (Better) HomeSlicker and 60 JumboTex
• 3-coat Stucco system
Here is my opinion on Zip-R panels I expressed on the previous question:
When it comes to Zip-R panels, not only is more expensive than regular OSB + foam, but I’m of the opinion that the foam on the Zip-R panel is on the wrong side of the sheathing, which places a much greater emphasis on quality control on the Zip tape installation. The reality on jobsites, in all states I work, is that it is very common for installers (framers) not to use the roller or to use it incorrectly. Installers miss-align, twist and miss-joint the tape constantly. Tape is installed weeks after sheathing installation. Sheathing installation was deliver in the mud or soil, not covered and weathered before installation.
现在，正常录制的OSB可以发生完全相同，但是您可以获得第二次机会，以覆盖顶部的面板接头，顶部和交错接缝。您可以从5-6.7中选择1“超出R值的外包板。检查回收的刚性泡沫，它很常用，便宜。
Nancy,
Q. "Do we need an intelligent membrane beneath the drywall on the inside of this wall structure?"
A. No.
问：“我们应该用什么用于防水气相透气屏障？”
A. Ether asphalt felt or housewrap (or both) are options.
问：“在湿岩下涂抹自粘膜是否明智，桥接拉链护套和混凝土基础之间的间隙？”
A. Yes.
Benjamin Obdyke recommends Slicker MAX 6mm for Stucco. There's also Delta Dry (Austin builder Matt Risinger is a fan of the product for stucco applications). I think either is a good idea for Western NC with the amount of rain you get (I grew up not far from Asheville).
Whether you go with ZIP-R or OSB/Tyvek/Foam it's only as good as the install.
10mm is probably overkill in your situation, but do what you feel comfortable with. MTI manufactures a product called肯定腔具有刚性垂直排水通道和砂浆阻塞织物。它比纠缠的网格类型产品更平坦。使用砂浆阻挡织物，您不需要在板条和排水垫之间的“防水蒸汽透气屏障”，以保持气隙清晰，并将胶带的拉链护套用作您的WB。
Recommend ventilating your wall system (vent at top, weep screed with large slots for draining and ventilation at the bottom) to make the most of the air gap. Here's an example:Thin Veneer to Top Vented Wall