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

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

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

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

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

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

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