Insulation: Ceiling Joist Spacing Not Standard

[cls89]

Hello, I’m currently in the process of insulating the garage. I’ve come across a problem with the ceiling. The spacing on the ceiling joist aren’t standard. This is only a problem on the addition part of the garage. It’s a 10x20ft area. Please see photo for visual of what I’m referring to.

The problem is the rolls of insulation only come in standard sizes such as 16” or 24” OC. These sizes wouldn’t fit these cavities. What’s the best way around this problem? We’ve come up with a few ideas. See list below. Please share your thoughts on what the best approach would be. Whether it’s on the list or something different. Thanks

1. Install paneling/drywall/plywood/etc on the underside of the horizontal support “rafters” and place the insulation from above. Essentially packing the insulation to fit the cavity. The plywood on the underside would be the support and I wouldn’t have to worry about stapling between the ceiling joists.

2. Correct the framing so that the cavities are standard which would allow to use the standard rolls of insulation. I don’t not a lot about framing, but I’m willing to learn. I would just need to do some research .

3. putting plywood on the bottom side and using a spray foam insulation and spraying from the top






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[HalfTonTom]

Cut the insulation to fit the cavities sideways and install bridging wood to staple it to?

 

[cls89]

Great idea! I didn’t think about cutting the insulation sideways. What do you mean by a wood bridge? Do you mean adding some 2x4 in between the ceiling joists and stapling the sideways insulation to that?


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[alien]

Strapping across all those joists and then unroll the insulation on top of it. You would have to cut some to fit the leftover space. Would probably be cheaper than adding two by fours at 16 or 24 inch on center.

 

[cls89]

Strapping across all those joists and then unroll the insulation on top of it. You would have to cut some to fit the leftover space. Would probably be cheaper than adding two by fours at 16 or 24 inch on center.

What do you mean by strapping? Would the strapping go on the top / attic part of the joists?


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[Bert_]

Why go to all that work when you can just blow in loose fill?

 

[spudley]

"Strapping" are strips of 1x material (furring strips) placed on the underside and perpendicular to those "joists".

 

[wrenchguy]

Why go to all that work when you can just blow in loose fill?

This, but the left bay touchy with that shallow roof pitch.

 

[cls89]

"Strapping" are strips of 1x material (furring strips) placed on the underside and perpendicular to those "joists".

I see. The only problem with that is that the ceiling already is kinda of low, and adding the strips on the underside would lower it a little more. Plus I plan on adding some PVC panels which would also lower it. But this would be easy to do.


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[Jim greengo]

Why go to all that work when you can just blow in loose fill?

What he said.

 

[cls89]

What he said.

I’m interested in this loose fill operation. Is there a good source that explains how it’s done, what tools are needed etc


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[Bert_]

I’m interested in this loose fill operation. Is there a good source that explains how it’s done, what tools are needed etc


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You put up your eve baffles, fill the remaining gap to keep the insulation out of the soffits and put up your ceiling.

Then you go to the lumber yard get your insulation and their blower. For 10x20 you'll be done in like 20 minutes.

 

[NUTTSGT]

Loose fill fiberglass or cellulose would work but I don't care for the latter. I'd add the ceiling and fill the space with full batts and cut some down to fill the gaps. Once that was done, a blanket layer running perpendicular to cover it up.

 

[sick467]

I'm not a big fan of the blow-in insulation. Mainly because it settles after time and, more importantly, if you need to run some wiring (or whatever) after the fact...it's just a nasty, dusty mess to deal with. It's good stuff, I don't want to knock it down too much, but consider putting up your ceiling (plywood or otherwise) and use Rockwool insulation on top of that. It will come in standard sizes, but cuts easily with a serrated bread knife and can be cut to fit to your spacing. It will have a better R value than fiberglass rolls and does not have the paper facing that needs to be stapled. It is rather stiff, but will push into place and expand back out to fill any gaps so long as it's cut a 1/2 to 1" oversized. It's still itchy like fiberglass, but with better properties and easier to use. Tip: put up one row of the ceiling then insulate above that, them move to the next row and so on. I just got done putting up 1600 sq ft of ceiling tin and used O.C. Thermafiber above it and I like it.

 

[The Cobbler]

Yes, blown in will save you grief, headaches, labour & probably be cheaper. My experiences is you can have blown in done by a pro for less than you can buy the batt material for.