Insulate roof, keep trusses exposed? Pics!

[seth586]

I live in a split house with 2 stall garage, nothing fancy built in 1980. The walls in the garage are half height cinderblock, then recessed 2x4. This spring I had the urge to hang things from the walls to 'get organized', so I doubled up the 2x4s so the recessed wall would run flush with the cinderblocks, installed fiberglass insulation, and installed fiberboard over the walls.

Now I want to insulate the roof.

The trusses are only 2x4s, and I like the extra space above the trusses to store long, light items, as well as give me a little more room over my shelving for storage, so I would like to run the insulation along the roof line, leaving the trusses exposed. The garage has no vents installed. I live in South Dakota.

I'm mechanically enclined but keep the abbreviations to a minimum, first time homebuyer here!

Can I just run more 2x4s up the 'triangle' wall to attach more fiberglass insulation?

How will I close the gap between the wall and the protruded wall I created?

Ugly...

 

[seth586]

So, the question is, how do I do it right? Do I need to install some sort of venting system, or can I run the fiberglass insulation directly against the roof?

 

[sjlee]

So, the question is, how do I do it right? Do I need to install some sort of venting system, or can I run the fiberglass insulation directly against the roof?

I'm pretty sure that you don't want to run the insulation directly against the roof. You want to have some sort of venting for carbon monoxide... as well as to prevent moisture from getting trapped.

 

[seth586]

http://www.menards.com/main/buildin...4-x-48-plastic-vent-chute/p-137194-c-5776.htm

So I looked at some youtube videos about insulating cathedral ceilings, which is kind of what I'm doing here, I'd have to run these pro-vents the entire length of the roof line. I still need an intake and exaust. The intake vents are just the roof overhang covers, except with holes in them, right? Do I run these between every truss? And for exaust, I assume I have to exaust all of them, which would be the entire length of the roof. I think I remember something at menards about a vent that covers the entire length of the steeple of the roof, like a mesh that you lay along the top and then glue shingles on top, would that do it?

I also assume that to get a decent R-rating I'll have to double up the 2x4s to fit the fiberglass insulation I'm thinking of?

 

[richtersrodz]

I had ridge cap put on my last house. They take a saw and cut the roof open at the very top, and then lay the ridgecap on, (nailed down) and then put shingles on top of it. It was kind of cool to see doves sitting on the ridge cap in the winter time. I climbed up on the roof, and warm air was going out of the ridge cap. So I guess it was working..

 

[sjlee]

http://www.menards.com/main/buildin...4-x-48-plastic-vent-chute/p-137194-c-5776.htm

So I looked at some youtube videos about insulating cathedral ceilings, which is kind of what I'm doing here, I'd have to run these pro-vents the entire length of the roof line. I still need an intake and exaust. The intake vents are just the roof overhang covers, except with holes in them, right? Do I run these between every truss?

I think you're referring to soffits... and you only need them wherever you have those provents installed.

 

[nwav8tor]

I had ridge cap put on my last house. They take a saw and cut the roof open at the very top, and then lay the ridgecap on, (nailed down) and then put shingles on top of it. It was kind of cool to see doves sitting on the ridge cap in the winter time. I climbed up on the roof, and warm air was going out of the ridge cap. So I guess it was working..

I'd not expect warm air to be coming out of a ridge vent during the winter. Shouldn't warm air should be kept inside the house by insulation, not up in the attic and exhausting through the ridge vent?

Paul

 

[Bigturk]

It is important to have good airflow under the roof deck to prolong the life of your roof shingles. Good airflow directly from soffit to ridge and between every rafter. A cathedral ceiling is difficult to vent properly. You only have a 2x6 rafter, after installing truevents, you can only fit 4 inches (R12) of insulation. Not enough R value to stop the heat from escaping into the night air. I would strap the underside of your rafters, poly vapor barrier,install some baffles to keep insulation from falling out into soffit and blow in some serious insulation. Maybe an R40 or R50. We lose most heat through the roof.

 

[seth586]

Ok I got the venting down, vented soffits, run pro-vents to the steeple, and install a ridge length vent. R38 insulation seems to be 12" thick! So should I run 2x8s along my 2x4 rafters so I can fit the insulation? Things probably just got pretty expensive

 

[tthornto]

You can save a little by just using 2x4s instead of the 2x8s. Just space them down with short pieces to where you have the insulation depth you want. You don't need the strength of a 2x8 your existing trusses will support the roof, what you are adding only has to support insulation and drywall.