Attic Insulation Floor or Pitched Roof

[8pack]

I have searched quite a bit on this and can't find the specific answer to my question.

-22x30 garage
-Attic is used for storage.
-Vented on the end, no other venting I can see.
-Ceiling in garage is 1/4" Sheetrock
-Hot Dog Heater recently installed.
-Parts of the attic already have nailed down flooring with no insulation underneath.

I lose a ton of heat through the attic and the garage temps drop very quickly when the heater is not running so the cost to bring the garage up to temperature on the days I use it gets pretty high. Keeping the heater running to maintain a minimum temp is even more. I have air sealed most of the rest of the garage but still need to insulate about 15ft of the back wall. That is a huge project that needs to be done in the summer when everything can be more easily moved anround and out of the way.

So, Can I put rock wool batts under the roof instead of the floor/ceiling? Blown Foam insulation is not in the budget.

The reason I am considering it is:
-To insulate the floor I would have to pull up some existing flooring which is a big job and move around a lot of stuff stored up there.
-access is a lot easier
-I would need to put end caps between the joists and then put flooring over the joists to keep the mice out which is also a big job.
-It seems easier to put rockwool on the underside of the roof and hold it in place with some 2x1 "straps. Feels like a 2-3 day job instead of a 2-3 week job.

I live in southern Mass and would appreciate any thoughts. I don't want to do something stupid or just waste money so if I have to **** it up and do the floor I will.

 

[AC-WC]

Putting the insulation in the roof rafters will not work because you have a vent on the end. All of your heat will go up, travel horizontally along the ridge and then out the end vent.
I think your easiest option is removing your attic floor.
1) pull up the attic floor and insulate with vapor barrier on the down side. Reinstall floor if you plan to use the attic for storage OR you could really beef up the insulation to R60 and get some serious heat retention. That may be code in your area. Garages may not be required for that level. R60 will be 18-24" thick.

2) You must have ventilation to move the air/humidity and just closing the end vent will not work. Confirm you have working soffit and ridge vents and then install rafter vents and insulate the rafters with vapor barrier facing down. Then close the vent(s) on the end.
No ventilation path between the soffit, rafter and ridge vents will cause all kinds or other issues which will cause significant building and health damage. If you don't have a ridge vent that runs the length of your roof you don't have a ridge vent.

This should help visualize-

How to Improve Attic Ventilation: What Homeowners Should Know

If ample fresh air isn't flowing through your attic, your home is at risk for ice dams, roof damage, ceiling leaks and other issues.

www.bobvila.com

 

[PCustoms]

I have searched quite a bit on this and can't find the specific answer to my question.

-22x30 garage
-Attic is used for storage.
-Vented on the end, no other venting I can see.
-Ceiling in garage is 1/4" Sheetrock
-Hot Dog Heater recently installed.
-Parts of the attic already have nailed down flooring with no insulation underneath.

I lose a ton of heat through the attic and the garage temps drop very quickly when the heater is not running so the cost to bring the garage up to temperature on the days I use it gets pretty high. Keeping the heater running to maintain a minimum temp is even more. I have air sealed most of the rest of the garage but still need to insulate about 15ft of the back wall. That is a huge project that needs to be done in the summer when everything can be more easily moved anround and out of the way.

So, Can I put rock wool batts under the roof instead of the floor/ceiling? Blown Foam insulation is not in the budget.

The reason I am considering it is:
-To insulate the floor I would have to pull up some existing flooring which is a big job and move around a lot of stuff stored up there.
-access is a lot easier
-I would need to put end caps between the joists and then put flooring over the joists to keep the mice out which is also a big job.
-It seems easier to put rockwool on the underside of the roof and hold it in place with some 2x1 "straps. Feels like a 2-3 day job instead of a 2-3 week job.

I live in southern Mass and would appreciate any thoughts. I don't want to do something stupid or just waste money so if I have to **** it up and do the floor I will.

Can you post some pictures?

You've used some conflicting terminology. I suspect you have soffit vents and a gable vent. I'm also not sure what you mean by blown foam, and am curious if your rafter/truss is actually meant for storage