Insulation sheets 4' x 8' ???

[Eazy716]

I've insulated all the walls, and covered with OSB.

now I'm looking to insulate the roof. wondering what the best bang for my buck is? I thought about using normal insulation rolls, but not sure it would be as cost effective as i would also need to buy the foam "channels" to allow the air to circulate behind it..

then I thought about using the 4' x 8' sheets of insulation to cover the roof....and allowing the air to flow above like needed. just not sure what thickness to go with. using this with the "shiny" mirror like side facing down will help bounce light around and brighten it up i think.

my question is what will be the most cost effective as well as store the most heat? right now the roof being open is sucking out all my heat when i try and heat it, and is getting frustrating in the buffalo cold.

what do you guys suggest? I figure i would need about 18 sheets of the 4' x 8' insulation to cover the entire roof. havent calculated how many rolls of insulation would be needed.

any insight is appreciated.

 

[6768rogues]

Would you be covering the ceiling or actually covering the roof and installing roofing over the insulation?
Most codes require foam insulation to be covered and not left exposed. Foam insulation is combustible (I know, big deal, so is wood) but it really accelerates a fire and it gives off really nasty smoke.

 

[Eazy716]

thanks Rogues, I guess that makes my decision easy, lol

it would be covering the ceiling, basically like you would if you hung drywall/OSB. but i guess i'll opt for the rolls of insulation. dont need any extra fire hazards.

thanks for the info!

 

[locoman]

Google p 2000

 

[5wndwcpe]

The proper vents (foam channels) are especially cheap and utilizing rolled fibreglas I think is the best way to go about it. A 2" thick polystyrene will only give you an R-10 factor and can get spendy in a hurry.

 

[83diesel]

I put the thick insulation rolls you put in your walls in the ceiling and then covered with osb board and painted gloss white, not only did it help in the cold winters with the heat bill but with the gloss white on the ceiling it brightened up the shop a lot, the board insulation does not seem to insulate as well due to air escaping around the voids b/w the insulation and the rafters.

 

[Eazy716]

thanks for the input guys!

i ended up picking up 16 rolls of insulation and started hanging it. im also laying the foam channels underneath.

i thought about puting OSB over it, but was concerned with the weight of it hanging over top. after i get the insulation up, i may go with OSB still, or possibly just some thin type of wall boarding to seal it up and not have as much weight as the osb.

 

[6768rogues]

I noticed that you live in Buffalo, NY. I am west of Rochester, so we have the same climate. If you have a modern building, it was designed for at least 35 lbs./square foot of snow load with some margin of safety above and beyond that. If you figure that OSB is 32 square feet per sheet, it does not weigh very much per square foot. Your roof structure is very under designed if it cannot handle that extra weight.

 

[Eazy716]

^^^thanks rogues. i actually had the entire roof ripped off from the box up ripped off and replaced this past summer....including beams etc.

its not so much the weight of the OSB bringing down the roof im worried about, but more the screws holding the OSB up without letting go over time. I'm sure im over thinking it, but the difficulty of actually hanging it is another key concern.

 

[5wndwcpe]

^^^thanks rogues. i actually had the entire roof ripped off from the box up ripped off and replaced this past summer....including beams etc.

its not so much the weight of the OSB bringing down the roof im worried about, but more the screws holding the OSB up without letting go over time. I'm sure im over thinking it, but the difficulty of actually hanging it is another key concern.

Properly sized and spaced screws will never let go over time.

 

[6768rogues]

If you are worried about it, you could glue it too.

 

[Designated Dave]

You've probably already done this as it is an older post but if you haven't, Drywall, or sheetrock lifts make short work of hanging osb on the cieling. That is how I did mine...(by myself)

 

[GSSFC]

The foam is not a fire hazard, but rather will ignite at a temperature lower than say fiberglass. If your house or garage burns, it doesn't matter what material you have in there. It will require at a minimum an ignition barrier and possibly a thermal barrier depending on your code requirements. The foam sheets are very good at stopping the thermal bridge that is created in the winter when warm air transfers to the roof deck via the rafters and creates the stripes you see on the roofs. R-Value of foam vs fiberglass is NOT apples to apples. Lower R-Value of foam does not imply lesser performance than fiberglass.

Tim