insulating attic over attached garage

Reply

  #1  
Old 06-14-10, 05:36 AM
Member
Thread Starter
Join Date: Jun 2010
Location: USA
Posts: 3
Received 0 Votes on 0 Posts
insulating attic over attached garage

We have just added a two car garage 22X20 to the front of our home with a large unfinished room above to be used for storage. The unfinished room has two windows one in front and one in back has electricity, ridge and soffit vents. The garage itself does not have any heat or air conditioning but also has two windows and and uninsulated garage doors. Access to the stoage room is through a door from a bedroom. Would insulation help cool the storage room or any suggestions on cooling this room. I was hoping to keep my small kiln and glass ginders in that room. And I hope I'm posting this question in the right place:-) Thanks

HelplessinNC
 
Sponsored Links
  #2  
Old 06-14-10, 12:12 PM
Member
Join Date: Oct 2008
Location: New England
Posts: 10,406
Received 23 Votes on 21 Posts
Hi helpless, the heat is obviously solar energy primarily from the roof. Light colored shingles would be a help, but yours are probably already in place. The next step would be to isolate the heat from the garage and allow it to vent out the ridge. A layer of rigid foam insulation over the bottoms of your roof rafters would insulate and isolate the heat to the cavity, where it would rise and vent out the ridge. If you choose the double foil faced polyisocyanurate (PIC) foam board, the two foil surfaced will, one reflect the heat from the roof back towards the roof and , two resist reflecting heat that does make it through the foam board, down into the garage. Black wood stoves radiate heat. Shinny metal surfaces do not. Use one or two inches of PIC and strap the bottom side so the long screws will hold it in place. PIC is expensive, and If you need a less expensive, less effective, option, we can come up with something. Place your strapping such that sheetrock could be applied later if desired.

Different towns view rigid foam differently and some require that it be covered with a fire rated barrier. Best to ask.

Bud
 
  #3  
Old 06-16-10, 05:48 AM
Member
Thread Starter
Join Date: Jun 2010
Location: USA
Posts: 3
Received 0 Votes on 0 Posts
insulating attic

Hi Bud,

Thanks for the info. Will the foam block my soffit vents? Does the foam board fit between the rafters. The room was created with a cathedral ceiling effect though it is only 7' 2" in height so I have 2 exterior wall that are 5 feet high and yes the roof shingles are in place, brown to match the rest of the house shingles. What kind of insulation would you recommend for the walls if any at this time. We have a sub floor in that room and there is insulation between the floor and the ceiling of the garage below. By the way the garage gets hot too:-) Thanks again from still helpless:-)
 
  #4  
Old 06-16-10, 07:45 AM
Member
Join Date: Oct 2008
Location: New England
Posts: 10,406
Received 23 Votes on 21 Posts
With the foam board on the bottom of the rafters, the cavity between the foam board and the roof plywood should form an air channel from the soffit all the way up to the ridge vent. That channel only needs to be one or two inches high, so you could cut, fit, and seal the foam board in between the rafters if you choose.

That cavity will get very hot, hot air rises and hopefully exits the ridge vent, pulling in cooler air from the soffits. Down at the bottom you will need to do some detail work to make sure the cavity pulls air from the soffit rather than from inside the attic.

When you say exterior walls that are 5' high, are these knee walls that look like they are supporting the slope of the roof at mid-point, forming small side attics like a cape?

bud
 
  #5  
Old 06-21-10, 05:04 AM
Member
Thread Starter
Join Date: Jun 2010
Location: USA
Posts: 3
Received 0 Votes on 0 Posts
insulating attic over garage

Hi Bud,

Thanks again. The 5ft walls are the actual exterior walls so the room over the garage is one big room same size as the garage below. Contractor built it that way to match the pitch of the roof to the existing house, as the garage was added to the front of the house, and to provide a room we could stand up in. Basically the room is for storage but I also do fused glass as a hobby and had hoped to use my grinders and glass saw in the room. The room has two windows one at each gable end and we already owned two window air conditioners bought when our house ac broke down a couple of years ago (to survive until the house ac was fixed), but as a novice I didn't realize the air conditioners would be useless in an uninsulated "attic" room expecially one of that size so I'm hoping insulation will help keep the room cooler in the summer and a little warmer in the winter. Sorry if this is more info that you needed:-) Helpless
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: