Another garage insulation/drywall and ventilation question(s)


  #1  
Old 08-21-06, 09:15 PM
S
Member
Thread Starter
Join Date: Nov 2003
Posts: 45
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thumbs up Another garage insulation/drywall and ventilation question(s)

Ok. Here goes. I live in MN and want to insulate my 26x26 detached garage constructed of 2x4s. No blocks. With little money last 2 years I hung 4mm plastic on the rafters to help trap the warm air when using a portable heater in the winter. Now I want to fully insulate the garage and likely hang a heating unit in the next year or so. But until them I am intersted in doing the job correctly.
First off, I have an overhang with good soffit vents. But no other ventilation. How many roof vents should I install? Or is ridge vent a better option?
Second, I am thinking of using 1/2 drywall. I believe that R13 is the max i can use to insualte the 2x4s. Is this correct? and what type of insulation should I use on the walls? Backed batts or not? What is the difference in the uses for backed vs. non? Also should I use plastic on the walls after insulation before drywall?
Third, 1/2 drywall on the rafters. Should I remove the plastic that currently hangs there? Or can i just hang the dry wall and insert the insulation from above(or blow it in)? Or should I remove the plastic and stable backed insulation, then hang the drywall?
So many question from an enthused garage guy..a cold one tho
thanks so much for any and all assistance...
 
  #2  
Old 08-21-06, 10:22 PM
Ed Imeduc's Avatar
Member
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 17,505
Upvotes: 0
Received 1 Upvote on 1 Post
Wink

Keep the poly on the ceiling. Id use 5/8" dry wall for the ceiling. R 13 in the side wall paper to the inside I still like to put a sheet of poly over it then the 1/2" drywall. if you will heat it latter put some foam vent boards in the rafter space .So air can get from the over hang to the attic. Blow Cellulose above the ceiling before it gets to cold.
Vents a attic needs 1 sq ft for ever 150sq ft of attic 1/2 in 1/2 out Go for button vent up near the ridge or in the gables if you have them.

ED
 
  #3  
Old 08-23-06, 06:59 AM
W
Join Date: Dec 2005
Location: USA
Posts: 3,051
Received 26 Upvotes on 21 Posts
Ed - Why go with blown in insulation when batts are so much easier to install?
I would go with 1/2" drywall on the ceiling if your joists are 16" OC. If they are 24" OC, then 5/8" is a better choice.
Unless you expect to have a large amount of moisture in your garage, I see no advantage for having poly sheets over kraft faced insulation. Just more work for little gain.
Installing ridge vents is probably the most labor and time intensive. Soffitt vents and either a mushroom or gable end vents are probably your best choice.
 
  #4  
Old 08-23-06, 09:31 AM
Ed Imeduc's Avatar
Member
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 17,505
Upvotes: 0
Received 1 Upvote on 1 Post
Wink

Wayne Mitchell Blow cellulose in the ceiling. Take a torch to the fiberglass Hey it dont burn. BUT it melts right away Now try the cellulose. It just turns black is all dont burn or melt. Have seen many home that got on fire from the roof. When they had cellulose the fire got stopped at the ceiling line. With fiberglass the whole home went.
Now on paper on the insulation. We dont staple it on the stud but put it in the stud. If you put 2 overlaps on the face of the stud. You will see bumps in the drywall. I dont care how hard you try you cant keep it smooth. Now like to use 2 mil poly but looks like now all you can get is 4 mil pol. Put it on the outside walls over the insulation windows, outlet and all. Then the dry wall. Now you have a good V/B over it all. Also the windows didnt get all full of yuk that you have to clean off from the tape and the paint. Now cut it off and put up the trim. Could use press tight fiberglass insulation in the walls then you need the poly. The poly cost is penny's and you sav $$$ in the end.
ED
 
  #5  
Old 08-23-06, 04:23 PM
W
Join Date: Dec 2005
Location: USA
Posts: 3,051
Received 26 Upvotes on 21 Posts
Ed - It's a detached garage not a dwelling. I don't know what drywall bumps you are talking about. I've hung quite a bit of drywall over kraft face insulation and not had a problem.
 
  #6  
Old 08-24-06, 02:55 PM
Ed Imeduc's Avatar
Member
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 17,505
Upvotes: 0
Received 1 Upvote on 1 Post
Wink

I have found over the years. When you try to staple the paper to the face side of the studs That make two layers of paper. You do end up with bumps that will show some times after the dry wall is up. When you put the insulation in and staple the paper to the side of the studs you will have some voids in the paper . Its not tight. So The 4 mil poly covers it all and gives you a good job with no air leaks. Dont forget to foam any holes in the top or bottom plates. For a home .A garage some dont even tape the drywall.

ED
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: