Insulating Roof and under slab

[rbmedic75]

as the title says I am getting ready to start my project 40x60 concrete poured walls 12' tall 10" thick. this is a welding/fab/garage. I am going to heat with radiant floor.

So the 2 main questions

Roof insulation -- It will be a metal roof with storage trusses, 14'X60' room (office/shipping/light storage) Trying to figure out the best route to insulate the roof. pretty sure I want to do the radiant barrier (double or single sided not sure yet) and then additional batt insulation of some kind it think. With the radiant barrier is that best applied to the top of the trusses under the purlins then the metal roof attached to the purlins (leaving about a 3/4 gap between metal roof and radiant barrier) then how do I put the batt insulation in. wanting to do it right but not spend boo kooo bucks on it (will be heating with waste oil)

Floor insulation my slab will be 4' below finished grade except for the walkout area where the gararge door and one man door will be. The question is di I really need to put 2" foam board insulation under the slab at 4-6' below grade. If not other options for the pex flooring fastening?



any links or suggested suppliers for any of the above mentioned materials would be great also. I have been doing my homework and searching but never hurts to have more suggestion and or thought.

 

[sneezer41]

>>>>Floor insulation my slab will be 4' below finished grade except for the walkout area where the gararge door and one man door will be. The question is di I really need to put 2" foam board insulation under the slab at 4-6' below grade. If not other options for the pex flooring fastenin<<<<

yes, yes you do. more is better

 

[jklingel]

under slab insulation: It all depends on how much fuel you want to waste trying to heat the earth. All slabs should have insulation under them, esp heated slabs. 2" is minimum for mild climates; 4" for cooler climates; 6" if it is cold in your area (northern u.s.) I will have either 8" or 10" of EPS under mine. Don't buy into the "XPS is the only way to go" story. I maybe used to be, but not any more. EPS is the preferred foam w/ many builders up here. There was a recent thread on this at greenbuildingadvisor.com, fyi, and many others. Read there and buildingscience.com. Sounds like a pretty sizable shop going up; good luck w/ it.

 

[nehog]

Big question is where is this being located? Georgia will have a different answer than, say, North Dakota!

Wood trusses? (One could make a good argument for steel there, too...)

 

[rbmedic75]

Shop is being built in Eastern Panhandle of West Virginia. Thanks for the answers thus far guys. Anyone got a good retailer to get the insulation board from.