cooling my attic in my garage

[Huntmaster86]

ive read through a bunch of posts about cooling attics but they didn't fit my needs. I have a 48x48 garage with 1/2 attic trusses. I blew 16" of cellulose to insulate the main garage ceiling and my walls are dense packed with cellulose. In the attic of the garage (24' long x 12' wide x7' tall) i have it almost completely sheathed with OSB and one wall insulated. I'm trying to cool that area down more as its very hot up there and im afraid my stored stuff up there is going to get damaged. I have sofit vents installed and a ridge cap vent. I used sofit baffles when i blew the cellulose in to prevent blockage. Any advise or input is appreciated.
Its very nice and cool in the garage so i know my insulation is working. I just dont know if finish sheathing and insulating the attic space is going to be enough or if im going to need some sort of a fan to cool the space. Im in norther NY so our temps are all over the place.

 

[TractorJeff]

Fans in the end walls?
Insulating the roof to keep heat out is the only real solution.
Rereading it, it looks like you are "finishing" a room up there for storage. Which would need to be insulated all the way around to prevent the heat from getting in. Obviously it would need ventilation inside of it to prevent condensation.

 

[Huntmaster86]

yeah im finishing the room for storage to try to prevent it from getting so hot. I keep my ice shanty and out board motors up there among other odd and ends. I have the stair way open as of now from the main garage to the room but i will install a man door eventually. would i want a fan blowing from the room to the outside or to the unfinished attic space? will i need an intake fan as well?

Ive thought about adding gable vents as well to try and cool it down up there but i havent installed yet. would regular R-19 all the way around the room be sufficient? or more on the ceiling? i have R-19 on one wall right now that i had left over.

hind sight i would of installed double bubble before my steel was installed on my roof.

 

[Huntmaster86]

could i install double bubble on the bottom side of my trusses or would that cause condensation issues and lead to mold? I dont have a vapor barrier below my steel. my layers are: steel roofing, perlins, truss to the attic.

 

[Denwood]

You will find this read on conditioned attic space helpful:

http://www.greenbuildingadvisor.com/blogs/dept/musings/creating-conditioned-attic

It's likely the best way to bring attic temps down.

 

[theoldwizard1]

... I'm trying to cool that area down more as its very hot up there and im afraid my stored stuff up there is going to get damaged.

It probably already IS damaged !

Gable end powered vent fan or several roof power vent fans.