Insulating garage that's already decked, best techniques?

[lethallyinjected]

I'm sorry, I know there's a gaggle of insulating threads going on right now but not sure this really fit into any of them. Good with my hands, been wrenching professionally for almost 15 years now, but just don't do much of the home type stuff. I was wondering how much pressure the blow in machines have, is it possible to maybe just hole saw at both ends of a section and blow in? Would it have enough oomph to push the insulation that far? Or will I need to pull decking up and lay in batts? I also see some people mention staying away from electrical that's ran, that it can warm the lines and cause problems or fires, but I just see it mentioned here or there... is that old home things, or??? I couldn't seem to find solid info on that when googling it. Buddy of mine that's the macgyver type even mentioned he'd be tempted to buy the cans of spray foam and just have at it with that. Open to any suggestions or tips, thanks guys.

 

[vavet]

I’m not entirely clear on what you’re doing. Are you trying to insulate in the attic, but you have plywood down to make storage space? You’re trying to insulate under the plywood so the ceiling of the garage is insulated?

I used the blowing machine from Lowe’s they let you borrow when you buy the insulation. It throws the material maybe 3 feet in front of you when held 3 feet up from the surface. If you garage is like 20x20, I don’t think you could get it fill the cavity by blowing it in from one end. Maybe you could do it in thirds...so if you have 20 feet, cut two holes, one at 5 feet from each wall. Then you’d blow it from the first hole outward towards the wall...and then turn it and blow it towards the other wall, but not actually expecting to get there. Once that area is full back to your first hole, go blow it from the other hole towards the area you just filled. Now you’re only asking it to blow 5 feet horizontally, the problem is that you won’t really know if your filling it.

You’d really need to try it, then remove the plywood from one section and see how you did.

 

[rburke65]

valet....same here...I have NO idea what they are asking.

 

[lethallyinjected]

I’m not entirely clear on what you’re doing. Are you trying to insulate in the attic, but you have plywood down to make storage space? You’re trying to insulate under the plywood so the ceiling of the garage is insulated?

This. Sorry, I must have had a moment.

 

[vavet]

This. Sorry, I must have had a moment.

No worries, I’m guilty of having half a conversation in my head before talking to someone else about the topic.

Check the specs on the blown-in insulation to see if you can get the R value you’re wanting with the depth that you would have if you left the plywood in place. IIRC, my insulation depth is about 12 inches to get R38.

 

[rburke65]

You wanting to blow insulation into the ceiling joists under the attic flooring, or the #tudded wall cavities?

 

[lethallyinjected]

You wanting to blow insulation into the ceiling joists under the attic flooring, or the #tudded wall cavities?

Under the attic flooring for now. The attic was decked over the garage before I moved in. The walls I was thinking about eventually trying the hole saw blow in technique, someone I'd talked to mentioned it worked well for him.

 

[matt_i]

I don't think it will work very well.

It might have the appearance but I don't think you will ever fully know about the gap underneath.

In the attic area of the original construction in my shop its roughly 16' wide and presumably they blew insulation from each end of the open cavity (between plywood and the drywall on each side of the attic area). I found a fairly large gap when I drilled a thru-hole for a copper pipe compressed airline. I felt certain I would be drilling thru solid insulation but it was all air. I am going to have to go back and try to pack it in from the ends.

In the shop addition I built there's a ton of obstructions to free flow, I have a wooden "hoe" that I have used to manually pack insulation down towards the center. I wish I would have done the temporary "2x" truss bracing until I put up the drywall ceiling, insulated, then added the attic floor. Unfortunately I did it while framing and nailed it all off with #10 ring shanks and so it would be a minor catastrophe to the floor surface to dig all the nails out with a cats paw.

 

[rburke65]

I thought they did a good job when a local company blew cellulose insulation between my attic trusses. And yes, I had the floor installed and a ceiling below. 32’ wide...blew each way 16’....stuff hose in +amity and blow...you can see when the insulation stops flowing in the ‘clear’ hose. Pull it back, starts flowing again...stops...pull it back...nice job.

 

[R6 Racer]

I used the blown in insulation in my shop attic. Used the stores machine that I bought the insulation from.
The machine came with a couple of sections of hose & a piece of pvc tubing about 4 to 5 feet long taped onto one end of one of the hoses. The added tube let me blow insulation easily 15 feet allowing for easy filling of the corners of the attic. Without the tube it only shot out maybe 5 or 6 ft. I don't know how much adding a tube to try & blow into such a confined space would help.
Just puttin it out there.

Steve

 

[yeldogt]

It's all in the operator ..... do yourself a favor and get an estaminet from an insulation company. The pro equipment is better and you may be surprised at the cost vs doing it yourself. The pros and in and out and it's don't ... they also get the product cheaper.