How to insulate attic above garage?

Reply

  #1  
Old 11-14-08, 10:19 AM
Member
Thread Starter
Join Date: Nov 2008
Location: Upstate New York
Posts: 4
Upvotes: 0
Received 0 Votes on 0 Posts
How to insulate attic above garage?

2 car garage attached to ranch style house has no insulation in attic. Hot water boiler in garage heats garage slightly causing ice damming on hip-roof joint above. Want to insulate but don't care to provide heat for comfort in garage, just to cool the attic enough so ice damming stops. Attic has fiberglass roll insulation above living areas & is vented (no current problems there). What type of insulation & R value can I install to accomplish this? Sheet rock ceiling in attic attached to 24" o.c. joists.
 
Sponsored Links
  #2  
Old 11-14-08, 12:02 PM
Member
Join Date: Oct 2008
Location: New England
Posts: 10,392
Received 20 Votes on 18 Posts
Hi Clarence and welcome to DIY. There are a couple of issues here you might want to talk about, the cost of having your boiler in an unheated garage and isolating your garage from your living space (attic included), but first your question.

You are correct, heat and air leakage into your attic will cause ice dams and upstate NY is certainly an area where that is a concern. If you take care of all of the air leaks and the attic is well ventilated, I would think 6 inches of fiberglass would do for a start. For living space below an attic they recommend R-50 or more, so more won't hurt. But some questions. Are you considering batts or blown-in? How much insulation in your main house? Do you have full soffit venting and a ridge vent or other? Are the walls in the garage insulated and sheetrocked? How is the boiler vented, chimney, wall vent? Is the boiler is a room by itself, or open to the garage? Is there a partition wall in the attic between the garage attic and the house attic? If oil, where is your oil tank? Let us know and we will comment.
GL
Bud
 
  #3  
Old 11-17-08, 02:03 PM
Member
Thread Starter
Join Date: Nov 2008
Location: Upstate New York
Posts: 4
Upvotes: 0
Received 0 Votes on 0 Posts
Attic uninsulated above garage

Bud / others, answers to questions: I'm considering batts, they are used over living areas @ 6" thk avg.; have full soffit venting + ridge vent. Exterior garage wall NOT insulated but sheetrocked. Back wall abuts family room & natural gas boiler is against this wall (in open area) w/ 4.5" galvanized round vent straight up to roof. Have new indirect gas fired water heater right next to boiler. I read the boiler needs ventilation. Cold air seeps in under exterior garage wall that is above concrete blocks and thru gap between door frame - on same wall. No partition wall between garage & living areas in attic.
Let me know what you think. Again, just want to cool attic & not interested in comfortable heated garage. Thanks,
Clarence W.
 
  #4  
Old 11-18-08, 05:45 AM
Member
Join Date: Oct 2008
Location: New England
Posts: 10,392
Received 20 Votes on 18 Posts
First air seal the ceiling in your house and garage. Locate holes for electrical wires and plumbing vents and anywhere air can get into the attic from house or garage. Fire rated caulking or fire rated foam insulation are best. Use metal flashing for any large holes. That is a big step towards cooling off your attic.

I'm troubled by the lack of a wall between your garage attic and your house attic. That puts the burden of isolating exhaust fumes from your house all on the garage ceiling. One of the builders on the this board might comment on this.

Since your garage is not heated, 6 inches of insulation in that attic will get you by, but you may want to address the lack of wall insulation and see if you can warm that space up a bit. Having your boiler and pipes in an unheated space can't be good. I know some boilers are built to be used out doors, but suspect a residential unit like yours is not. Insulate all heat and hot water pipes you can. How to deal with improving this installation, or whether it needs improvement is a question you could post over on the boiler thread. Great people over there.

As for the 6" insulation over your main living area, it needs another 6 inches minimum for R-38 and they recommend up to R-50. Another project, but an area that will certainly reduce your heating costs, and help with the ice dams. As you take steps to warm your garage up, you will want to increase the insulation out there as well.

That should keep you busy. I hope gas prices are falling as fast as heating oil.

Bud
 
  #5  
Old 11-18-08, 01:59 PM
Member
Thread Starter
Join Date: Nov 2008
Location: Upstate New York
Posts: 4
Upvotes: 0
Received 0 Votes on 0 Posts
Attic uninsulated above garage

Boiler was installed when natural gas became available (replaced electric heat) and there is no basement. Construction inspectors did not comment adversely on boiler location when I bought the house. I have insulated all piping which runs up into attic, then down to rooms (glycol-hot water baseboard). As for fumes, there are vent pipes common to kitchen/bathroom away from garage. Looks like I'm shopping for a bunch of insulation (after sealing holes in garage ceiling). Don't believe I can enclose units in garage since they require ventilation. Heating bills have not been too bad for 1300 SF ranch. Thanks, Bud for the advice.
Clarence W.
 
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: