Insulating garage - how to handle unfinshed ceiling joists?

[snowphun]

I'd like to insulate my attachd garage, this means insulation for three walls and the ceiling. The issue with the ceiling is I have 2x8 joists then a large unfinished space above (see attached picture). I'm not really interested in sheet rocking the ceiling, can I use some type of batts to hold the insulation up? Any other ways to handle this? The space above the garage is effectively useless.

Thanks.

 

[Thruxton]

I would think that after you have installed insulation, finishing the walls and ceiling (your choice of materials) is your best bet. You need to protect the insulation, and you will gain even more r-value and weatherproofing, plus you can finish the surface with a brighter material, making your shop more usable. And it's not all that hard to do.

 

[Steevo]

You can staple kraft-backed insulation between the joists, and leave it exposed if you want to. I have even seen it spray painted to look better and reflect more light. Eventually, after you have jabbed it with a long piece of something you are working on and now have tears showing, or had something fly apart and some small part breaks through that paper, only to be lost forever, you may re-think sheathing over it.

 

[NUTTSGT]

Like Steevo said, the kraft paper will hold it up but it will sag in the middle.

 

[RHD 4 LIFE]

Use some 7/16" OSB sheets, they are very inexpensive and quick to go up! Don't forget to install the vapor barrier before the OSB though. Then just paint!

 

[Lakeozark]

2x8 Joist' should be enough to put in Kraft faced R30, R38 might be too thick.

I put up R30 between my rafters and stapled to the joist as Steevo mentioned. I can personally attest that you will want to cover it up though....I havent got to dry all yet and I am already tearing the kraft facing by hitting it with things.

 

[kbs2244]

Before you go with the OSB check out 1/4 inch plywood.
They sell it as "underlayment," or "Luan."
It is stiffer than OSB and less likey to sag.
And it is a whole lot lighter than drywall.
Paint it white before you put it up.

 

[samert111]

I used Kraft faced R30 batts. If you leave it uncovered, eventually the kraft paper dries out, sags more and in general starts to look bad.

I put up the metal Durapanels to cover it up and protect it.

Here's a photo of the ceiling partially installed and one of the end result.

 

[snowphun]

That looks great. My concern is there are plenty of things already on the ceiling (light fixtures, garage tracks, fan, outlets...) that putting up plywood or sheetrock will be a PITA. But it sounds like leaving it uncovered eventually becomes a problem. Bummer.

 

[Mario]

I used Enermax panels in my garage addition and put fiberglass mats over it.

http://www.bpcan.com/en-CA/products/soundproofing/sound-deadening/enermax-east-/

I did put fiberglass mat directly over plastic sheating in my old section and it did sag so Enermax panels will probably be installed there soon.

 

[Bigrhamr]

As everyone has mentioned covering it with something is preferable. But, if that's just not going to happen or won't happen for a while then you can staple it up plus run a series of wires maybe 12" apart and stapled to each joist. Something like chicken wire would work even better, looks a little funny but so does sagging insulation. They make some metal clips for the same purpose but IMO they don't work any better.

 

[snowphun]

Thanks for all the ideas. Mario's post brought up a thought: what about a rigid insulation? Can I affix that to the underside of the ceiling joists instead of sheetrock or plywood? I'm guessing it's lightweight and easy to cut.

 

[Mmfh]

Most of the home centers have the insulation boards that are like Styrofoam sheets, 4'x8' sheets. I haven't used them for what you are thinking but it seems like they would work well and also be easy to work with.

They are lite enough that holding them up would be no problem and cut easy with a knife. Probably used something like long roofing nails to hold it up.

Plus they are white and would brighten it up in there real fast!

Mm

 

[djb25]

Thanks for all the ideas. Mario's post brought up a thought: what about a rigid insulation? Can I affix that to the underside of the ceiling joists instead of sheetrock or plywood? I'm guessing it's lightweight and easy to cut.

This is exactly what I used in my garage. I have a relative with a large commercial roofing company who has pallets of rigid foam insulation. I screwed the foam to the ceiling and then taped the seams with hvac foil tape. The stuff I used is either r9 or r11.

The stuff installs easily with long screws and big sheet metal washers. Make sure you buy the good tape, though - I ran out of the good stuff and tried to finish with some "duck brand" foil tape from wal-mart - it was falling off within a month.

We did this with a lot of garages and it works great. We used to be able to get foil-backed sheets which worked great for light-reflection. The new stuff has an asphalt coating that I painted white.

It's a great way to quickly install insulation and finish the ceiling.

Last note - leaving the Kraft paper backing exposed on the ceiling is a pretty serious fire hazard...

 

[NUTTSGT]

I used some foil backed rigid insulation in part of my garage. I used the nails with the plastic washers for tar paper. After I had it up, I covered the orange washer with foil tape. When you tape the seams between the sheets, it's easier if you have another person help to make sure it's straight.

 

[Falcon67]

But it sounds like leaving it uncovered eventually becomes a problem. Bummer.

Why - I spent 12 years in my old shop with just insulation stapled to the joists. I used a few 1x2s as straps to keep it in place. Still there, never any issues with it. Half the walls were unfinished also.

See here:

Fire hazard? Sure, so is the bit a 1/4 OSB I used in places. So - be damn careful. Own a circular saw and still have 10 complete fingers? Same deal.