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#1
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Insulation question
I am insulating the ceiling in my garage. The ceiling is 2x8 16 on
center with dead space above. I am using R-30 batts. Now, I know these will stick up about 2.5" and that's fine for now. But if someday I put a rough floor up there for storage and compress it, what's the downside if any? Does compression hurt the R value? It seems to me I would still be better off then using R-19. Thanks, Jim |
#2
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Insulation question
On Sep 29, 2:40*pm, jtpr wrote:
I am insulating the ceiling in my garage. *The ceiling is 2x8 16 on center with dead space above. *I am using R-30 batts. *Now, I know these will stick up about 2.5" and that's fine for now. *But if someday I put a rough floor up there for storage and compress it, what's the downside if any? *Does compression hurt the R value? *It seems to me I would still be better off then using R-19. Thanks, Jim For every inch you compress subtract the inch R value rating. If 10" is R35 than 9 will be R31.5 |
#3
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Insulation question
Yes, compression hurts the r value. AND if it's trusses, you can't put
anything up there. s "jtpr" wrote in message ... I am insulating the ceiling in my garage. The ceiling is 2x8 16 on center with dead space above. I am using R-30 batts. Now, I know these will stick up about 2.5" and that's fine for now. But if someday I put a rough floor up there for storage and compress it, what's the downside if any? Does compression hurt the R value? It seems to me I would still be better off then using R-19. Thanks, Jim |
#4
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Insulation question
On Sep 29, 11:03*pm, "Steve Barker DLT"
wrote: Yes, compression hurts the r value. *AND if it's trusses, you can't put anything up there. s "jtpr" wrote in message ... I am insulating the ceiling in my garage. *The ceiling is 2x8 16 on center with dead space above. *I am using R-30 batts. *Now, I know these will stick up about 2.5" and that's fine for now. *But if someday I put a rough floor up there for storage and compress it, what's the downside if any? *Does compression hurt the R value? *It seems to me I would still be better off then using R-19. Thanks, Jim- Hide quoted text - - Show quoted text - I'm missing the math, but this is a garage with 2x8 rafters spanning 19'. I will be putting R30 (9.5") up there and if I do put some plywood on top for a little storage it will compress it to 7.5". So it sounds like even with the compression I'm better off then the alternative of R19. Am I off base? -Jim |
#5
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Insulation question
No, you are correct. 7.5 inches is greater than 6.
steve You still can't load the bottom chord of a truss however. Are they trusses, or conventional rafters and ceiling joists with support poles? "jtpr" wrote in message ... I'm missing the math, but this is a garage with 2x8 rafters spanning 19'. I will be putting R30 (9.5") up there and if I do put some plywood on top for a little storage it will compress it to 7.5". So it sounds like even with the compression I'm better off then the alternative of R19. Am I off base? -Jim |
#6
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Insulation question
On Sep 30, 10:00*am, "Steve Barker DLT"
wrote: No, you are correct. *7.5 inches is greater than 6. steve You still can't load the bottom chord of a truss however. *Are they trusses, or conventional rafters and ceiling joists with support poles? "jtpr" wrote in message ... I'm missing the math, but this is a garage with 2x8 rafters spanning 19'. *I will be putting R30 (9.5") up there and if I do put some plywood on top for a little storage it will compress it to 7.5". *So it sounds like even with the compression I'm better off then the alternative of R19. Am I off base? -Jim They are conventional rafters and ceiling joists, 16" OC 19' span. I know I'm being thick, but given my example of compressing R30 by 2.5", what do I end up with? -Jim |
#7
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Insulation question
23.625
arrived at that figure by dividing 30 by 9.5 and getting about 3.15 then divided 19 by 6 and got about 3.15 then multiplied 7.5 times 3.15 s "jtpr" wrote in message ... On Sep 30, 10:00 am, "Steve Barker DLT" wrote: No, you are correct. 7.5 inches is greater than 6. steve You still can't load the bottom chord of a truss however. Are they trusses, or conventional rafters and ceiling joists with support poles? "jtpr" wrote in message ... I'm missing the math, but this is a garage with 2x8 rafters spanning 19'. I will be putting R30 (9.5") up there and if I do put some plywood on top for a little storage it will compress it to 7.5". So it sounds like even with the compression I'm better off then the alternative of R19. Am I off base? -Jim They are conventional rafters and ceiling joists, 16" OC 19' span. I know I'm being thick, but given my example of compressing R30 by 2.5", what do I end up with? -Jim |
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