泡沫三明治采用2英寸开孔喷雾泡沫+刚性泡沫屋顶护套？
Hello,
我在一个完全重建的规划阶段，我的4楼的第二楼。我的目标是1个带R30 +墙壁和R60屋顶的ACH。我的方法是一种混合墙/屋顶组件，使用螺柱之间的外部刚性泡沫+蓬松/透气绝缘（图4和下面的BSC链路的图7）。我计划在外护套上使用流体施加的WRB。
Because of my ACH goal, should I be looking at open cell spray foam in addition to the fluffy insulation between studs? Am thinking 2-in open cell because it’s more vapor open compared to closed cell (30 perms at 2-inch thick?). I know it’s borderline risky in my mixed climate zone. Plus I’d purposely be creating a foam sandwich on the roof sheathing.
如果开放式电池过于危险，我应该考虑一个智能气旋延迟器，如SIGA的MAJREX，以封装屋顶椽子之间的透气绝缘的底部？我可能必须在屋顶框架的底部和我的密闭式干墙天花板之间的小阁楼空间中运行HVAC线。
My plan is to contract out ~50-75% of the work using a detailed build-to spec; I want to add these details to the spec. Thanks in advance for your help!
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答复
墙壁中开放电池的目的是什么？如果它是板条护套，可以有一个用于增强气密性的开放电池的参数，但如果胶合板/ OSB，岩石羊毛绝缘材料的较低成本降低了。
At the roof the amount of exterior foam matters. If the exterior foam is more than 30% of the total R it's fine to use all-fiber or open cell foam in the rafters bays. If it's less than 30% of the total you'd need a minimum of 1" of closed cell foam on the underside of the roof deck (2" is better- at 2" most closed cell foam is barely into the Class-II vapor retardency range, and not a true vapor barrier), but the combined exterior + closed cell needs to be more than 30% of the total R to avoid moisture accumulation in the fiber insulation.
对于屋顶甲板+ R30岩棉上方的2LB Polyiso屋顶泡沫（R23）的区域4a气候4“（R23）（适用于2x8椽子），将使您在中心腔处于r53，但会优于阁楼填充阁楼的速度。如果椽子是2 X10S，椽子可以填充1.8LB玻璃纤维（〜R39），它将达到〜R62，舒适的37％R比率。
Even at the 37% ratio there needs to be at least a Class-III vapor retarder (such as standard latex primer on gypsum board) on the interior side, but a smart vapor retarder is even better. It's possible to use the Intello Plus vapor retarder in lieu of blowing mesh for installing 1.8lb fiberglass, (an idea promoted by 475 High Performance Building Supply, distributor of Intello products) which isn't a bad way to go.
Awesome, thank you for the feedback Dana! Like most Cape’s, my roof line is a bit complicated - 4/12 on the front with 1950 slanted Pine plank boards, and 1.5/12 on the back with OSB sheathing. All roofing framing members are 2x8s.
Am planning on 6” taped polyiso on the roof, which will be installed over a fluid applied WRB on the existing sheathing. I may put a layer of crinkly Tyvek over the top layer of polyiso for peace of mind. This is followed by 1-by strapping, another layer of OSB, felt, and shingles or aluminum/metal shake panels.
Under the sheathing, I plan on using rockwool - either R30 bats for the 2x8 rafters or 2-in open cell to help with air sealing the planks + R24 batts. If using only the R30 batts I could staple a smart vapor barrier to the framing to create a decent secondary air barrier. My primary air barrier is the gypsum panel ceiling.
石膏天花板直接触及前倾斜框架的下侧。倾斜部分过渡到脊柱的平坦天花板〜2.5英尺。在平坦的天花板上方是一个小角度的阁楼空间，在山脊上18英寸，在拱门处收缩至0-高。不幸的是，我可能必须使用这个空间来运行HVAC / ERV线路。
我将使用类似的墙壁方法（我有一个木板壁护套和OSB的混合物），但使用4“Polyiso和R15 Rockwool。我的壁板很可能是Bith砖块和纤维水泥或金属抖动。
再次感谢您的帮助和建议！
>"Am planning on 6” taped polyiso on the roof, which will be installed over a fluid applied WRB on the existing sheathing. I may put a layer of crinkly Tyvek over the top layer of polyiso for peace of mind. This is followed by 1-by strapping, another layer of OSB, felt, and shingles or aluminum/metal shake panels."
There is no advantage to the crinkly Tyvek when it's next to an air gap between the OSB nailer and polyiso. Cheaper flat-stock is fine.
>“在护套下，我计划使用rockwool - 用于2x8椽子的R30蝙蝠或2英寸开放电池，以帮助空气密封板+ R24 Batt。”
当使用施加的流体或完全粘附的膜（冰和防水罩，蓝色罩等）作为板条护套上的WRB时，它将是气密的，并且对开放式电池泡沫没有任何优势 - WRB已经制造出来气密。开放式电池泡沫并不是非常光滑的，并且会在泡沫和毡之间留下气口/空隙。2“开放式电池泡沫的射击将是一种不必要的费用，这将由2”厚的岩棉毡厚度优异。
Great, thank you again again for the help Dana! The more I think about it the more I like the idea of R30 rockwool with a smart vapor retarder on the underside. This is something I could do, which would help save money.
One additional question - what are your thoughts on by-brand low temp performance of polyiso? I’ve found some data on Thermax but not on other manufacturers. For an exterior roof/wall application, is Thermax worth the ~2x cost delta compared to another brand (say Rmax)? Am also thinking about a foam sandwich to help increase assembly R values at low temps, where a 2-in or 3-in layer of EPS/XPS would reside over 4-in or 3-in layer of polyiso. I’m not in wild fire country, but fire resiliency is at least a consideration. Thermax’s performance becomes a mute point if I do the foam sandwich approach.
谢谢！