retired1
New Member
Posts:29
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| 10 Dec 2009 11:27 AM |
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I'm planning to build here in the Rocky mountains at 9600' elevation next summer and a it's been -5* around here this week in Denver so my thinking cap is always working. Has anyone used 8" wall panels? Any problems? The wood clad windows with jamb extensions to drywall face is no problem. With the wood exterior doors maybe a problem due to exterior metal jamb limitations. I have thought of a recessed door frame but do not like that. Using Kolbe & Kolbe windows and doors.
Thoughts, please, thanks.
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jerkylips
Basic Member
Posts:359
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| 10 Dec 2009 12:36 PM |
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I had a similar question a while ago. At the time I wasn't looking at SIPs, but was looking at doing 2x8 exterior wall construction vs 2x6, and using urethane foam. Talking with a local insulation contractor, I was told that you quickly hit a point of diminishing returns with regard to insulation. He said that they had done some research on similar issues & found that if the house is tight, there wasn't much of a difference in heat loss between an r-28ish wall and an r-40 wall.
Basically the answer I got was, 'it won't hurt to do it, but you won't get your money out of it." Part of the reason was what you mentioned - in addition to the extra cost of the walls, you have added expense of jam extensions, etc.
I'm sure someone with more knowledge on the subject will give a better answer, but that's what I have heard. |
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retired1
New Member
Posts:29
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| 10 Dec 2009 06:10 PM |
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Thanks "jerkylips" for the reply and comments.
Retired1 |
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trigem1
Basic Member
Posts:123
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| 10 Dec 2009 07:16 PM |
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Retired 1,
Living here in the Rockies does present certain challenges. And although I agree to a certain extent to jerkylips, that was a stick built home and I think the extra insulation would be beneficial. First, the 6 inch SIP wall has an R value of about 24, and the 8 inch wall has an R value of about 32. That’s more than a 25% improvement. That’s like going from an R 19 wall to an R 24 wall. In northern Canada, builders aim for R 40 to 60 walls and R 60 to 80 roofs. So, the diminishing returns depends on what temperatures you have to contend with. The colder it gets, the higher the R value you want. The other great heat loss is windows and doors. I’ve known people who build SIP homes and put in huge windows and then complain that SIP’s aren’t as good as what they were told. Consider smaller windows and maybe triple pane windows and insulated doors with good seals. Also consider some kind of solar, either photovoltaic and/or solar water heating. When you get right down to it, as you’re building your house, a liberal use of caulk and foam sealant can go a long way to the comfort of your home.
Steve
GrandCountySIPs.com
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| Steve Etten |
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jerkylips
Basic Member
Posts:359
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| 11 Dec 2009 09:12 AM |
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Posted By trigem1 on 12/10/2009 7:16 PM
Retired 1,
Living here in the Rockies does present certain challenges. And although I agree to a certain extent to jerkylips, that was a stick built home and I think the extra insulation would be beneficial. First, the 6 inch SIP wall has an R value of about 24, and the 8 inch wall has an R value of about 32. That’s more than a 25% improvement. That’s like going from an R 19 wall to an R 24 wall. In northern Canada, builders aim for R 40 to 60 walls and R 60 to 80 roofs. So, the diminishing returns depends on what temperatures you have to contend with. The colder it gets, the higher the R value you want. The other great heat loss is windows and doors. I’ve known people who build SIP homes and put in huge windows and then complain that SIP’s aren’t as good as what they were told. Consider smaller windows and maybe triple pane windows and insulated doors with good seals. Also consider some kind of solar, either photovoltaic and/or solar water heating. When you get right down to it, as you’re building your house, a liberal use of caulk and foam sealant can go a long way to the comfort of your home.
Steve
GrandCountySIPs.com
you bring up a good point about the windows. In a perfect world, I'd do 8" SIPs, triple-pane windows, etc. BUT...we're all on a budget. So as far as "bang for your buck", would you agree that it may make more sense to stick with the 6" SIPs and put the extra money into windows instead? |
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richm
Basic Member
Posts:107
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| 11 Dec 2009 03:01 PM |
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retired1, jerkylips and trigem1,
Installing the 8" would make more sense to me and then buying the best window you can within your budget because you will be able to change the windows in the future (when better and less expensive ones are readily available) but it sure would be prohibitive to increase your wall thickness!
Rich Melius |
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cmkavala
Veteran Member
Posts:4327
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| 11 Dec 2009 03:58 PM |
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Retired1;
it might make more sense to keep the 6" wall and increase the roof by 2 " , which would also increase your snow load capacity |
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| Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br /> |
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trigem1
Basic Member
Posts:123
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| 11 Dec 2009 05:29 PM |
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I got the old calculator out, and say that I decide to go with the better windows and thicker SIP walls and roof, and it would raise my budgeted home cost by $8000. At 6.5% interest, it comes out to about $51 extra per a month for a 30 year loan. At today’s heating costs, it probably isn’t that big of a deal. But in 20 years, the heating price could easily double what it is today. So, the question is, is it worth $50 a month?
Steve
GrandCountySIPs.com
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| Steve Etten |
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stonecaveman
Basic Member
Posts:123
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| 15 Dec 2009 07:29 PM |
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I, personally, went with exactly the richm philosophy. 8" SIPs and fairly good, mostly double pane vinyl windows. I plan to change out the windows whenever something much better becomes available. In the meantime, in the coldest weather, you can always add something like these Window Treatments from "Build It Solar". The extra cost for 8" vs 6" was not that much (< 10%). It's relatively hard to add more insulation to the walls later (I have that to do also). I would agree with Chris that adding to the roof insulation is probably a good plan even if you don't increase the walls. I have heard that at higher altitudes the heat loss through the walls is less than at lower elevations, supposedly to do with the density of the air, but I've never seen hard number to back this up (anyone?). |
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retired1
New Member
Posts:29
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| 16 Dec 2009 01:29 PM |
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Thanks for the thoughts. I failed to mention that I'm committed to using 12" roof sip's. Received the door jamb wall thickness posiblities from my supplier and it looks like I'll be sticking with 6" sip walls. |
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stonecaveman
Basic Member
Posts:123
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| 16 Dec 2009 01:41 PM |
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Building out the door jamb should not be a major problem - at least not so large that I'd base a major portion of the envelope design on it. On the other hand, if you're sure you'll be happy with either 6" or 8" and have no other decision criteria, then it's probably as good as anything. |
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