How to Insulate.

[grinthock]

So I think I planned this wrong, my GC was also a bit of a *****.

I wanted scissor truss, I like the idea of a high ceiling, what I didn't consider is how hard it would be to properly insulate this.

- Spray foam? What about venting if I do that?
- Batts?
- Ceiling material?

I've attached some photos...

There are soffit vents around it and roof vents now. Just not sure what my options are - either way I don't know I will be able to do it myself even if I do rent a lift again. Don't worry about the lights/FAN that can obviously all come down and be moved or modified.

Thoughts?

 

[matt_i]

Personally I'd do fiberglass batts held in place with wire-rods "lightning rods". Then drywall. It would be good to go all future electrical that you ever plan to do, first.

 

[tyme2par4]

I'm not sure what would be hard? Just run fiberglass batts between the rafters, then drywall.

 

[Falcon67]

X3 - batts. You can use 1x2x8s across the truss cords as temp supports to help the staples keep the batts in place until you can cover. Lotsa work, need a good lift and scaffold but doable.

 

[Firebrick43]

Are you wanting to just have some below energy code insulation like r19 or a good job like r38+??

If higher amounts I would put attic rafter vents up(need to do no mater what) and have that area along the edges spray foamed. Then faced batts in between the trusses or unfaced and a plastic vapor barrier.

 

[coldh2o]

Are you wanting to just have some below energy code insulation like r19 or a good job like r38+??

If higher amounts I would put attic rafter vents up(need to do no mater what) and have that area along the edges spray foamed. Then faced batts in between the trusses or unfaced and a plastic vapor barrier.

^^ this. I'm in central Ontario and insulated my scissor trusses with fibreglass batts. I didn't spray foam around the lower ends because I had raised heel trusses which gave enough room for rafter vents and R-40 insulation. You don't, so the spray foam is a great option.

 

[grinthock]

^^ this. I'm in central Ontario and insulated my scissor trusses with fibreglass batts. I didn't spray foam around the lower ends because I had raised heel trusses which gave enough room for rafter vents and R-40 insulation. You don't, so the spray foam is a great option.

I'm in Central as well, what are are you in? I'm near Orangeville. Interested in how you did it, and any pics if you have.

I'm trying to understand what you are saying about the vents, basically i need to ensure that the air from the soffits, makes it into the roof, and isn't blocked by the insulating material....

For me it's man handling all that stuff, at that height, if I do it with a scaffold it would be one hell of a job and i'd be up and down like crazy and moving that kind of scaffold around would be a big job all on it's own. If I did it with a lift, i'd have to really have my things togeather otherwise the lift rentals would kill me.

Almost wondering if it's worth hiring the job out.

 

[Firebrick43]

I'm trying to understand what you are saying about the vents, basically i need to ensure that the air from the soffits, makes it into the roof, and isn't blocked by the insulating material

Exactly.

The problem is you don't have enough depth for r38 insulation at the edges in fiberglass. Spray foam would but is expensive so only do it out a couple feet till you have sufficient depth for your fiberglass.

If you DIY you need a man on the ground helping by handing up material and moving the scaffolding.

I don't know in Canada but here insulation subcontractors is one that DIY is normally a wash. They get enough discount on materials and their labor rates are lower than other more skilled trades.

Get a quote or two. You may be surprised.

 

[DC73]

You can spray closed cell spray foam on the underside of your roof and completely do away with any ventilation.

See BuildingScience.com and GreenBuildingAdvisor.com for much more information.

DC

 

[joe--h]

What is you're venting? Garages don't generate moisture like houses do.
No kitchen, no showers, no source of moisture so no need for venting.
Joe H

 

[Jazz1]

I would use batts as they are cheaper. With the scissor lift you have you could be unrolling vapour barrier and stapling it up as you go along. Some areas you are not going to get R40 in but not a issue since you do have attic vented. I would also get the drywall up immediately afterward since you have the scissor lift. Consider external conduit for wiring.

 

[Jess]

Batts and vapour barrier, then drywall. We did all mine at 16' from scaffolding. I hired out the hanging....

 

[NUTTSGT]

What is you're venting? Garages don't generate moisture like houses do.
No kitchen, no showers, no source of moisture so no need for venting.
Joe H

Depends what he's using for heat. Natural gas will produce moisture.

Also if the OP has shingles unless he spray foams right against the roof deck, he needs ventilation or the heat can destroy the shingles.




I guess I don't understand what the general contractor did to be called a ***** ?

I'd put baffles down towards the bottom of the roof deck, going up far enough to get past the insulation. Stick fiberglass batts in there and be done. I'd use whatever R-value thickness of insulation you can at the edges, even if it means compressing it a little bit.

Once the insulation is done, I'd put metal siding up, it's one and done. No finishing, caulking or painting.

Rent some scaffolding for a week including wheels so it's easy to move and to hang the metal, buy or rent a drywall. You'll have to make an extension for it to reach the upper part of the ceiling. I'd also recommend buying an electric staple gun for hanging the insulation. You might need to buy extra staples but it will be well worth it.

 

[toyotadriver]

Vented natural gas heat won't add moisture. Unvented heaters (not including electric resistance heaters) of all types will put tons of moisture into the garage.

To the OP...if you do batts definitely vent the roof. If you do spray foam, use at least 2 inches of closed cell foam then fill the remainder of the cavity with the appropriate thickness of fiberglass.

What I would likely do if I was in your position in your climate would be to install foam vent channels on the roof deck. Then put as much fiberglass batts as you can afford....at least R30 but more be better. Then, cover the batts on the underside of the roof with rigid foam....2 inches would be perfect. Then screw white metal siding over the foam. Would give really good r value and still be vented.