Re-siding and need to re-insulate but need advice
Hello,
I live in a 47 year old ranch house in Southern Maine (climate zone 6).
我计划在春季重新坐房屋，并希望在我坐下时改善隔热材料。我特别想改善房屋的前部，并在正面向北时保持空气密封。
The house currently has 2 x 4 stud walls with Owens Corning kraft-faced 1965 fiberglass (I think it’s supposed to be R-8), 3/4″ pine 1×12 sheathing, tar paper, and cedar shingles. My wife and I have lived in it 7 years and in those 7 years I’ve removed all the old wood framed single pane windows and replaced them all with vinyl new construction windows with built-in J channel. I plan to re-side the house with cedar look vinyl siding. (something like Certainteed’s Cedar Impressions).
Anyway, to get to my question. This is what I’m thinking of doing:
After the siding is off, rip off the 1x sheathing, and then cut and fit polyisocyanurate foam into the stud cavities. I plan to cut it about 1/4″ small on all sides so it can be foamed in place with Great Stuff Pro. The rigid foam would be held back in the stud bay so it’s up against the sheathing. I’m thinking of either using 1 7/8″ (R 12.2) Tuff-R since Home Depot has it as a stock item.
腔泡沫到位后，我不确定该怎么做。理想情况下，我想用刚性泡沫包裹房屋的外部，以获得更多的空气密封并切断热桥梁。为了避免卸下/重新安装窗户，我正在考虑安装新的7/16英寸OSB护套，并将其粘合到螺柱上。然后，我想在OSB顶部安装1/2英寸Polyiso并贴上接缝，然后安装乙烯基。这将等于15/16英寸的泡沫/护套厚度，现在仅比3/4英寸的护套高3/16。如果专家建议使用更厚的东西（例如1英寸泡沫），我将不得不卸下窗户并重新安装它们，以便避免这样做。但是我也知道，外面更多的泡沫通常更好。我只想这样做一次，然后做正确的事情，所以我想我会在这里要求从聪明人那里获得一些建议。
If you’ve made it this far, thanks for reading my ramblings. I look forward to any advice people can offer. Thanks!
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Replies
Brett,
I don't recommend that you remove your sheathing or do anything to your stud cavities. Your existing sheathing is sound -- 1x12 boards make excellent sheathing, and it's a shame to remove the boards.
Any improvement to your insulation is best done with a continuous layer of insulation on the exterior side of your sheathing. Most people would choose some type of rigid foam; I advise you to use polyisocyanurate, the thicker the better.
It's true that you may have to remove the windows, or at least find a way to flash the windows carefully without removing them. But since this job is only done once every 50 years, it's worth doing right.
Thanks for the reply, Martin. So just an exterior foam layer and nothing else? I was thinking I definitely had to do something in the cavities. That's good news in terms of labor required.
If nothing is recommended for the cavities, I'll probably use the 1 7/8" polyiso Tuff-R that HD sells.Would you recommend putting Tyvek on top of the foam (or under it), or just install the foam, tape the seams and put the siding on?