Home>Discussions>INSULATION & HVAC>best way to insulate a ranch garage ceiling?
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NickL
best way to insulate a ranch garage ceiling?
NickL

I will be insulating a garage this spring. The home is a flat ranch, The roof of the house is a continuous gable witch covers the living space and garage. Since the living space is @3 ft highter than the garage floor, The garage walls extend 11 ft from the floor at the lowest point where the roof rafters start, and up from there to the peak. the garage is 12ft wide and 24 ft deep. It is currently unfinished. There are 2x4's that run front to back of the garage every 16 inches. Whats the best way to get at least R 43 in the ceiling (Home is in Ct). My thoughts were to use R13 faced insulation between the current ceiling joist (the 2x4's that run front to back) and sheetrock the ceiling. but after that I'm not sure if I should use batts or blow in insulation. My fist thought was to run 2x6 perpendicular to the 24ft 2x4's every 23 inches, That will sure up the pretty wobbly 2x4 there now and can get batt insulation in that width.That would get me R43.
The wall between the home and the garage is insulated. There is a gable vent on the opposite side of the home, and a solar roof fan about 10 ft from the garage wall now. I was going to open a hole in the attic wall separating the home and garage then add a gable vent on the exterior garage gable wall.
The garage will never be used for living space, but will probably add a gas, vent free heater in the future.
Now I'm sure you laughing at my plan, (as I am now that i am writing this.) which is why I'm asking for help !!! Any thoughts will be appreciated.

dj1
Re: best way to insulate a ranch garage ceiling?
dj1

Your existing 2x4 joists may not be able to carry the weight you are planning to load over them.

NickL
Re: best way to insulate a ranch garage ceiling?
NickL

Yes, I agree. The 2x6's I planned on adding that will be installed perpendicular to the existing 2x4's will sit on top of the wall top sill. I will need to place a 3.5 inch block on the sill to insure the bottom of the added 2x6's touch the tops of the 2x4's. I planned on using twist straps to tie them together. This was the ceiling load will be more on the 2x6's. Unless there is a better way to accomplish it?

ed21
Re: best way to insulate a ranch garage ceiling?
ed21

Needless to say 2x4 24' long are about twice what code allows for an uninhabited attic.
I think a better approach would be to add a beam center span and perpendicular to the 2x4s, install insulation baffles or blocks at the soffit and then blow in insulation.
The wall between the house and garage is for fire protection, but a ceiling in the garage should allow an opening to be put in. Officially no opening in the garage ceiling would not be allowed unless it's covered with a rated door/covering.
The new beam can be above the 2x4s and fastened to the existing ceiling joists.
Ridge vents in general are good to have if you plan on reroofing anytime soon. If you have Vented soffits be sure baffles are used that don't block the airflow.

NickL
Re: best way to insulate a ranch garage ceiling?
NickL

that sounds good, would a double 2x6 with plywood between the boards be enough of a beam. centered in the 24ft span. Or would you suggest splitting the area into 3, and installing 2 sets of 2x6's 8 ft apart?
Do I have to use type X sheetrock for the entire ceiling, or just where the attic access hole is?

ed21
Re: best way to insulate a ranch garage ceiling?
ed21

I don't believe type x is needed for ceiling. Local codes can tell you what's required. As far as a hatch goes the codes are a bit picky about garages being able to allow fire getting into the house structure.
Without running numbers I'd be more inclined to use a 7 1/4" lvl or at least double up 2x8s

NickL
Re: best way to insulate a ranch garage ceiling?
NickL

great thanks again, will use 2x8 and check with local codes here...

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