Aces High Bulletin Board
General Forums => The O' Club => Topic started by: rabbidrabbit on October 27, 2004, 04:08:33 PM
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OK,
Doing a remodel and going with a cathedral style ceiling in the great room. My question is what kind of insulation would be best? There is a total drop in the center of the roof of 4 ft and I'm supposed to have R39 in the ceiling. I think there is attic batting to get up to R39 but is that my best option? Isn't it really expensive? How do the different types of insulation compare.. batting vs. styrofoam vs the blown in stuff... Any thoughts?
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Styro is the best and easiest, but also the most expensive. If it is a cathedral ceiling, how much space do you have between rafters and actual ceiling?
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well.. at the peak of the roof I have 4 ft between the bottom of the ceiling and the top of the roof. The frame is 2x4 trustle. Can you get blown in styrofoam anymore? I guess I'm trying to figure out price vs performance and making sure I'm not forgeting any options. Got to be somone here who can give me some straight numbers on what my options are and a rough price per square ft . I'm figuring a total roof area of 900 square Feet. Any pointers would be appreciated!
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Sheet styrofoam placed between the rafters is optimal, but blown in will most likely be cellulose. Bat is the cheapest, and if you have 4' is probably the best option.
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yup, 18 inch fiberglass is best for that.
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Are you going to use sheitrock for the ceiling?
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The best insulation is sprayed foam. It turns your house into an icechest and acts as it's own vapor barrier, but it is a bit pricey and it's permanent.
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R30 bats cost about .52/sf. I do remodeling. Ive never used or been asked to install batts higher that R30 in residential construction.
Rigid foam board would be more expensive to reach the same R value.
Make sure you have proper venting at the eves. Styrofoam makes a thin molded channel that keeps insulation from closing up airflow where the wall and trusses meet. Its really important in a vaulted ceiling. Lack of venting under the roof sheeting shortens shingle life, and can even cause moisture problems in the ceiling.
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yes but i thought he had 4 feet beteen his roof and his ceiling. if thats tha case r38 bat will do.
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I suspect they are sissor trusses, and at the bearing point he has about 7-1/2" between the top and bottom. Less than that if you measure perpendicular with the ceiling.
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The only problem with foamed in is the moisture problem. I'm also guessing that the actual clearance will be too small to lay bats.
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How thick do R39 bats run? I have plenty of room at the peak (4FT) but it gradually thins down to about 10-12 inches by time it hits the outer wall. As far as bats go, whats the best brand to use or does it matter? Is the cheapest the best? Any real difference?
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18 inches
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Huh? R30 is 10" R38 is like 12" standard, but iioc owens makes a dense line that is a little thinner than standard.
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For residential batt products its pretty much certianteed and owens corning. Cant say Ive noticed a diffrence to prefer 1 over the other for like products.
Assuming you are using kraft faced batts, and a drywall ceiling, I'll add another pointer. Dont staple the tabs on the bottom of the truss. Staple them just around the corner on the sides of the bottom truss cord. Otherwise the paper tabs are apt to cause 'nail pops' in the wallboard over time. Plus if you plan on glueing it (as recommended on a ceiling) the glue is worthless if its on the paper.
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Originally posted by Murdr
For residential batt products its pretty much certianteed and owens corning. Cant say Ive noticed a diffrence to prefer 1 over the other for like products.
Assuming you are using kraft faced batts, and a drywall ceiling, I'll add another pointer. Dont staple the tabs on the bottom of the truss. Staple them just around the corner on the sides of the bottom truss cord. Otherwise the paper tabs are apt to cause 'nail pops' in the wallboard over time. Plus if you plan on glueing it (as recommended on a ceiling) the glue is worthless if its on the paper.
If I understand you right.. staple the bats on the inside of the truss, not wrap it around the outside... correct? So, cheapest is generally best because they are all pretty much the same.
Also,
Any pointers on truss ties? My basic plan is to copy the truss system in our bedroom which covers a similar width (30 ft). Is gluing advised if I'm using truss ties? Don't see any evidence of it in the original but it's a good idea to figure out what will will give the best performance for the price / effort.
Thanks again!
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Originally posted by rabbidrabbit
If I understand you right.. staple the bats on the inside of the truss, not wrap it around the outside... correct? So, cheapest is generally best because they are all pretty much the same.
Also,
Any pointers on truss ties? My basic plan is to copy the truss system in our bedroom which covers a similar width (30 ft). Is gluing advised if I'm using truss ties? Don't see any evidence of it in the original but it's a good idea to figure out what will will give the best performance for the price / effort.
Thanks again!
Right, leave the bottom 2-by surface exposed so that the sheetrock can be fastened to it directly.
They are pretty much the same between like products, just make sure you're not compairing apples to oranges.
By truss ties I guessing you mean bracing the trusses together by fitting 2x blocks between them (bridging)? (I know terminalogies vairies between regions) Mimicing your existing home construction is a good plan if its also pre-manufactured trusses. Id recomend always glueing ceilings. There are less problems with cracks and pops when the sheetrock is bonded to the framing, and "DSA" drywall adheasive is not that expensive. IMO glueing walls are not as critical, but it is pretty common to see that in a job spec. also.
Ive litterally spent weeks at a time going through apartment units fixing drywall, and 90% of the problems wouldnt have happened if it had been glued.