Is this a Good Final Envelope Decision?
G'Afternoon！我是犹他州盐湖城的住宅设计师，经过一年的研究网站，绿树统计学，GreenBuildIndisor＆Blbg科学公司与客户辩论各种墙壁信封选项的优点，我的客户和我已达到以下内容关于外壳的决定：9英尺的墙壁是24“o.c的2×6木螺柱。喷涂玻璃纤维腔绝缘/陶氏品牌1“结构绝缘护套W胶带/灰泥饰面。BTM和顶板填缝/密封，所有渗透泡沫密封。预期的壁r值约25.平板上的W级连续2“平板刚度下的刚性。（客户仍然辩论辐射热）。金属屋顶OVR毛毡/ OSB OVR凸起高跟鞋Premanuf Trusses。闵。R-38吹入阁楼insul。 Low-e windows, 3 ft overhangs std. FYI, the home is to be built in Southern Utah in a mixed-dry climate (nearly identical to Alburquerque, NM). Total SF: 3154
So, whadda you Folks here think about this combination?
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Replies
Tim,
It sounds like a good plan. I would add a second WRB for stucco, Tyvek StuccoWrap or #15, and/or maybe a rain screen for best performance. I don’t know what transition you have from 1”SIS panel to 2” perimeter insulation, but it would make sense to have another layer of 1” Dow blue board on top of the SIS panel; or if you are installing radiant heating, you need R10 min. insulation under the whole slab, and then you may not need perimeter insulation.
I think the 1" SIS on studs 24" OC is a pretty bouncy substrate for stucco. I would want something more rigid to apply stucco to unless you are going with a very thin and very flexible synthetic stucco type product.
Tim,
Michael makes a good point... I would look at the insatllation instructions on the stucco you are using and see if your wire mesh nailing pattern will allow you to be nailed at 24" o.c. with a three coat stucco, if it is less than that you'll need to use wood sheathing. In NM we use plywood or OSB with regular blue board on top of it.
Timothy,
我会更加关注Windows。短语“Low-E Windows”并没有告诉我们很多。
瞄准所有窗户的低U因素。为南侧选择高SHGC的玻璃;东方和西方的方面应该用低SHGC获得玻璃。面向朝下的窗户的SHGC并不重要，所以在那里安装任何类型。
Thanks all for the comments. First, I think the comments about the stucco is relevant and I will look at this deeper...in the realm of windows, we are indeed specifying windows with approp u-vales for region & orientation. I didnt include every bit of info in order to keep down post length...and DOW claims their SIS product does triple duty: "STYROFOAM SIS™ Brand Structural Insulated Sheathing combines structural lateral bracing and transverse load, insulation and water-resistive barrier properties...the 2" rigid insul I mentioned is under-slab & continuous - so there is no "transition" from the 1" SIS panels to the 2"...THANKS AGAIN EVERYONE!
Someone clarify the foam thickness issue for me. Is the climate for this build mild enough (appears to be ~4300 HDD) that 1" of exterior foam is adequately warm on the inside face so as not to condense? I recognize that there is not wood sheathing installed here, just the foam, but if there were condensation it might just accumulate at the bottom plate of the wall.
Im thinking that condensation at btm plate shouldnt be an issue - even if moisture does get in there - since exterior face of stud framing is set flush with fdn wall. Bottom of SIS panel is below that point. Proper flashing details should prevent any further worry. Again, tho, the SIS panel advertises itself as avail with WRB applied to both faces...