Insulation Aggravation

[DanMan]

I realize this topic has been gone over and over. It's just that I can't seem to come up with a workable solution regardless of where I search. And search I have.

The structure in question is a 12x24 detached block wall garage with a stick built gable roof structure with asphalt shingles. No collar ties are used. No ridge or eave vents, either.

I am hoping to provide some means of insulation to make it more comfortable as a small woodworking shop for 4 seasons. The "ceiling" is the problem.

While creating a horizontal overhead ceiling is certainly possible, I would like to maximize overhead height.

What is necessary to insulate above the walls? I am in central New Jersey.

 

[CNGsaves]

Welcome to GJ. It's good that you are looking to insulate as best way to improve use of garage.

Lots of options for you based on cost. What's your budget?? What are wall construction (2x4 or 2x6)?? What does ceiling look like??

Best to take a bunch of pictures.

 

[DanMan]

It's high time I get with the times and learn to post pictures on web forums.

It's the roof structure I am concerned with. Standard 16" oc 2x8 construction.

Budget is as low as possible using accepted methods.

 

[p_mori7]

Welcome to GJ !

You need to insulate it like a cathederal cieling. See pic.




For the air space between the underside of your roof deck and the top of your fiberglas batts, you can use baffles like this:




Then a poly vapor barrier stapled to the bottom of the rafters.

 

[DanMan]

Thanks for the reply, and the welcome.

I was hoping there was an easier, softer way. Much of what I read indicated the use of ridge and soffit vents, with a baffle system to channel the airflow. Another option calls for a system wherein the vents are not necessary but seems to call for massive amounts of insulation. An "all or nothing" approach.

I was hoping someone had a way to do this that would not lead to problems such as rot and mildew at the roof sheathing down the line. I am not living in this space, I just want to do battle with some of the temperature extremes.

If I chose to suspend a ceiling instead of maintaining the "cathedral" aspect, would other vent systems be an option?

 

[James-W]

I think putting in a ceiling and insulating above it would be the best way to go. But if having the maximum height possible is essential, then I would get in touch with someone who does spray foam insulation. Odds are they have run into similar situations before and they can steer you in the right direction in-so-far as the venting and so on. Everything I have read about spray foam indicates it is wonderful stuff, but it will cost you more money than regular insulation. On the other hand, the insulation properties are better so it won't take as much of it to do the same job and that will give you more open space, which is what you want.

 

[WanderingSol]

DanMan, what keeps the roof from coming down and pushing out the side walls?

 

[megalo]

If it has a ridge beam (not board), it wouldn't need the rafter ties to prevent spreading.

 

[dave67fd]

Keeping the ceiling open you will need means of keeping the heat down as you will loose "all" your heat up there. Ceiling fans are a must in that case. There's no real easy or inexpensive way of doing it properly. Again, depending on how you heat it consider the costs of heat loss if done improperly.

 

[jrfiero]

DanMan -
With any insulation except foam you will need ventilation to prevent condensation and possible rot and mildew.
Foam you can spray right on the plywood or sheathing.
You can do a "flash and batt" wherein you spray about an inch of foam, then use fiberglas or other insulation to get up to your target R value.
You can buy a foam kit which does 600 sf of 1" (R7?), but it'll cost $600.
FYI, 2006 code required R-38 in ceilings/roofs, which IIRC is 12" of fiberglass, more than fits in a 2x8. You could do a flash and 6" R-19 for a total of R-26 and it will make a huge difference compared to no insulation.
Good earlier questions about your structure, however. Without collar ties you need a structural ridge to keep the walls together. With a 12' wide building if you have a high pitch the force might not be too bad, but the more weight you put up there (insulation, for instance), the higher the lateral pressure will be.

Any plans for wall insulation? The block walls will transfer heat right out through them.

Jonas

 

[CNGsaves]

Lots of speculation . . . . kinda like woman calling in for auto service and tech asks what kind of car . . . .and she says . . . its a BLUE car !!!

You likely have a cell phone, it likely takes pictures, send PIC TEXT to yourself by changing the outgoing phone number instead to be Your Own email address. Now pic can easily be pulled down to your harddrive. Then edit GJ first post, Go Advanced, then Manage Documents, then Browse up at top and go find the Picture (repeat the Browse step and you can attach 7 pictures to a post), click Upload, click Close this Window, and finally click Save. Best to save your pictures in JPG format.

You may have structural issues that need fixed BEFORE you can even consider closing that space up and insulating. Lots of gurus here on GJ could help you out.

Same message, different day:

 

[jrfiero]

Why Pictures? Re: Insulation Aggravation

What's the big advantage in having pictures?

12x24, block walls, 2x8 rafters, unvented roof. The only thing we may have missed is the pitch, but really, now much more do you need to make insulation suggestions?

Jonas

 

[DanMan]

Wow. Thanks everybody for responding. Seemed to have died out early and I kinda gave up hope thinking this thread would get buried.

Look-I am not looking to live in this space. Just hoping to control the environment a bit. I know. Do it once and do it right. That's always good advice.

I struggled with the vapor barrier issue. Seems to be something that is done wrong more often than right. I've come to the conclusion, whether wrong or right that I will do as follows to the walls:

3/4 board insulation liquid nailed to the walls. 2x2 furring with pressure treated shoe on edge. 1 1/2 board insulation between the 2x2's. OSB or T-111 panels next.

Initially I thought that the roof would be more of the same. Glad I found out that if done wrong it could lead to damage.

Now the big question-what to do. Time and money at a minimum. If it's not DIY, it won't get done. Little by little works for me.

The rafters are 2x6, not 2x8. My mistake. The roof rises 4 ft in 6 ft.

As to my picture posting skills. With a pc I had half a chance. My pc gave up the ghost. I am using an IPad. Not a fan. 'Nuff said.

 

[dmsween]

I had my whole detached garage sprayed with foam. I had thought about doing a drop ceiling but wanted to still be able to store things in the rafters. I can get my garage up to 80 when its in the single digits outside.. Got quoted 3" on the walls (2x4) and 4" on the roof (2x6) and they went over the rafters in some places. Foam acts as a vapor barrier so I don't have to worry about that.