Insulating new garage?

[zeekh]

Built a 44' x 22' over the Summer. Winter is coming, my finances have recovered its time to start thinking about insulating the building. I have a few questions. Walls are 10' high. There are attic trusses in the front 18' of the building, and scissor trusses in the rear for possible lift installation. Will eventually put in a drop ceiling in the front making it a 9' foot ceiling. I paln on putting 2 x 8's on the Scissor trusses to get rid of the vaulted ceiling for heating reasons. I'm thinking about using EXP foam board to insulate the ceiling. Mostly because that will be an area where air lines and other type of elecrical stuff goes to the rear of the garage. So I will be working in the area above the drop ceiling often. So I'm thinking of insulating attic floor with ~ 7.5" of foam board. With and R value of 5 per inch that will give me R35+ in the ceiling. Walls are 2 x 6 construction and I paln on using R21 fiberglass insulation. Slab is not insulated underneath but has 2" foam board around the perimeter and horizontal foam board extending 2' out from the edge of the slab.

Anyone see any problems with my plan. Any input or experiences would be appriciated

Thanks

 

[kd3pc]

we use R50 in the ceilings and R30 in the walls and it does not get near as cold here in TN as it does upstate.

I would at least do that much in your area.

 

[Stuart in MN]

Walls are 10' high. There are attic trusses in the front 18' of the building, and scissor trusses in the rear for possible lift installation. Will eventually put in a drop ceiling in the front making it a 9' foot ceiling. I paln on putting 2 x 8's on the Scissor trusses to get rid of the vaulted ceiling for heating reasons.

I don't think dropping the front ceiling or covering up the scissors trusses would help that much for heating...

 

[zeekh]

we use R50 in the ceilings and R30 in the walls and it does not get near as cold here in TN as it does upstate.

I would at least do that much in your area.

Wouldn't r 30 fiberglass in 2 X 6 walls over compress the insulation and reduce r value.

 

[zeekh]

I don't think dropping the front ceiling or covering up the scissors trusses would help that much for heating...

Dropping the front ceiling for easier mounting of lights in drop ceiling. I figured the 20' ceiling peak at scissor truss end would collect the heat at ceiling level

 

[Fisherguy]

Wouldn't r 30 fiberglass in 2 X 6 walls over compress the insulation and reduce r value.

Good question...

 

[LB-1911]

Wouldn't r 30 fiberglass in 2 X 6 walls over compress the insulation and reduce r value.

Good question...

Courtesy of Owens Corning -

Insulation R-Values When Compressed In Framing Cavity2

 

[skippydoo]

I built a 30x40 with 13ft ceiling height. The truss's are open up to the peak with is 19ft. I had the building spray foamed, 3'' in ceiling and 2 in walls. I'm waiting on the guy to hook my radiant heat up. I bought a 21k BTU electric heater and it will heat the place to 60 no problem. Low temps outside 12 to 25 degrees. I keep it at 50 when I'm not working inside. Very impressed with closed cell foam so far.

 

[zeekh]

Courtesy of Owens Corning -

Insulation R-Values When Compressed In Framing Cavity2

Thanks. I probably should have googled it.

I was thinking spray foam but that stuff is pretty expensive. It'll be tough convincing the Mrs. That it's a good idea.

 

[zeekh]

I built a 30x40 with 13ft ceiling height. The truss's are open up to the peak with is 19ft. I had the building spray foamed, 3'' in ceiling and 2 in walls. I'm waiting on the guy to hook my radiant heat up. I bought a 21k BTU electric heater and it will heat the place to 60 no problem. Low temps outside 12 to 25 degrees. I keep it at 50 when I'm not working inside. Very impressed with closed cell foam so far.

Did you spay foam directly to the roof decking? If so, shouldn't there be an air so the roof can breath?

 

[skippydoo]

Did you spay foam directly to the roof decking? If so, shouldn't there be an air so the roof can breath?

Their is an air space . Foam isn't touching the metal anywhere. My sofits and ridge vent still work.