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trojanman1 09-16-2009 11:30 AM

Garage insulation question
I live in San Diego in an area where the Summers can get to about 105 degrees, and in the Winter it might get down to 40 degrees. I have a 1959 home with a 2 car attached garage. I am making the garage into an entertainment area (Man Cave if you will) and am going to be drywalling the entire room. At this time, the roof is pitched and everything is wood studs. The walls are about 9 feet high with open "A" framing which makes the peak of the roof about 14 feet at the very top. I am installing 2x4 supports in between the "A" framing every 16" to allow drywall installation. I am also reinforcing the "A" frames to accomodate the additional load. My question, based on the region that I live in (Southern California) is whether or not I can install insulation in between the new 2x4's I am installing in the ceiling or if I have to install the insulation all the way up just under the actual roof. I will be using a small area in the "attic" for storage of some seasonal items, but nothing important will be up there and I will have an access panel in the ceiling to get to the "attic" space. So... can I simply install the insulation between those newly installed 2x4's? This would make my life much easier!

Thank you for your time!

Scuba_Dave 09-16-2009 11:43 AM

How far will the 2x4's be spanning?
A 2 car garage is usually at least 18' wide - which is too far for a 2x4
Any picture of the framing?

trojanman1 09-16-2009 11:45 AM

Garage insulation
I will post a couple pics tonight when I get home. However, the average distance between each "A" frame is about 48", so my 2x4's are spaced every 16" in between the "A" frames. Does this make sense?

Scuba_Dave 09-16-2009 11:51 AM

Ah, so you are putting 2x4's between the A frames & not wall to wall
That's different, but not better
The A frames you speak of are trusses
Any modification to a truss needs to be approved by an engineer

If you know who built the house, or the Truss Mfg you can get the information on the trusses & determine if they will hold the additional weight of 2x/drywall & insulation

Other then that you would need an engineer to review & approve

trojanman1 09-16-2009 12:13 PM

Garage insulation
Sure wish I knew someone in my area that could take a look. Maybe I should just put the insulation where the rafters on the pitched roof are and call it a day.

drtbk4ever 09-16-2009 01:03 PM

Try to post a few photos. A picture is worth a thousand words.

You may as well try to do it correctly the first time as any shortcuts now can cause major problems down the road.

Gary in WA 09-16-2009 02:34 PM

" distance between each "A" frame is about 48" --- sounds exactly like rafter ties (required every 48") and rafters. Your Building and Land Use Departments have it together! There is all the info you need: I suggest you get a permit for safety and if selling- no problems. Notice some of the particulars required, this on rafters for safety:
G. Roof Framing Plan
If you are modifying existing framing in the roof area (for example, to provide ceiling joists where the garage roof framing presently is comprised of rafter and rafter ties only), a roof framing plan must be provided. Include the following information:
1. When modifying rafters, please indicate hips, valleys and ridges for both new and existing construction. Dimensions of both new and existing roofs.
2. Rafter and ceiling joist size and spacing.
3. Any special framing at the roof area.
For information on sizing rafters and ceiling joists see Information Bulletin 133, “Roof and Floor Framing Span Tables.” Any proposed framing not meeting conventional construction standards may require submittal of plans and calculations by a registered design professional licensed in the State of California.

Also insulation required, p.t. ply and framing on a slab, new foundation under garage door opening, and BONUS--- no school tax if 500sq.ft. and under conversion.
Be safe, Gary

vsheetz 09-16-2009 02:51 PM


Originally Posted by trojanman1 (Post 328472)
Sure wish I knew someone in my area that could take a look. Maybe I should just put the insulation where the rafters on the pitched roof are and call it a day.

The concerns expressed are not for the placement of the insulation, it's primarily the weight of the drywall you are adding. You are modifying and adding weight to trusses which must be properly scoped and accomplished.

Once properly done, the insulation can go between the ceiling joists and/or on top of the drywall. You can use insulation batts, rolls, or blown in. This might be a good time to go with blown in and upgrade the insulation in the main house at the same time.

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