Insulating help needed: Ceiling is garage door panels

[Dan Jansen]

I’m looking to put heat in the shop for next winter. I’m getting bids on the heat but will insulate the attic myself. I’m not sure how to best insulate it. I live in central Illinois so R-38+ is my goal. The interesting component is my ceiling consists of garage door panels. I didn’t build the shop but we have a nearby garage door manufacturer and these panels were seconds. It’s a very clever ceiling design. It’s bright white and comes with an R8 value and each panel is airtight when locked together. The panels are 12’ long and my shop is 24’ long so there’s one gap/butt joint down the center that I will seal up with a can of spray foam. With garage doors as my base layer, do I need to worry about a vapor barrier before unrolling the batts, should I get paper backed insulation or use the unfaced insulation batts?

I’m not really interested in the hassle of renting and use loose fill unless there’s some significant advantages that I’m unaware.

[Andrew Seemann]

With a ceiling like that, you shouldn't need a vapor barrier. Unfaced batts should be fine. My preference is loose cellulose. It is easier to get into the nooks and crannies and works better as a ceiling insulation than fiberglass, at least based on my last shop where I needed to use both in different places. The fiberglass part often had snow melted over it, and the cellulose rarely did.

[Carlos Alvarez]

Just keep in mind that the cellulose settles, and loses value. My house, at six years old, had lost 30% R-value when an energy audit was done.

[Darcy Warner]

Blown in chopped fiberglass.

[John C Cox]

Blown in chopped fiberglass.

Thinking about this just makes me itch all over...

[Marty Tippin]

Hire a local company to blow in some insulation - fiberglass or cellulose - you'll get much better insulation with a whole lot less work than trying to use batts.

I'm no expert, but if your ceiling panels are already insulated to R8, I can't see why you'd need to worry about adding a vapor barrier.

[Carlos Alvarez]

Thinking about this just makes me itch all over...

My 7th level of hell is being a fiberglass insulation installer who has to work naked.

[Jim Becker]

I agree that blown-in insulation over top, assuming you have access, is the "best" solution, but unfaced batts/roll insulation is a perfectly valid method, too.

[Darcy Warner]

Thinking about this just makes me itch all over...

The white chopped fiberglass doesn't seem to bother me at all. It wont settle like cellulose, no dusty mess.

[Jim Andrew]

My local lumberyard will deliver out the insulation and the blower, you need a person to dump the bags into the hopper on the blower while you run the hose in the attic, then they will pick up the leftover insulation and the blower. Takes about 4 hours to do a 2000 sf attic at r 30. Be sure to wear a good dust mask, and put a trouble light in the attic you can move around as you blow the insulation.

[Bill Space]

HI,

I used blown in Fiberglas insulation to insulate the 1200 square foot house I am renovating as a retirement project, and it took about four hours to do it, insulating to R60. Takes two people, one to feed the machine (son in law) and one to work at the end of the hose (me). Blowing machine was provided free by Home Depot since I bought the insulation there.

There was no itching involved. I wore a dust mask (or respirator, don't remember which, have both) and it was pretty simple and fast. Wonderfully fast, compared to the time and effort it would have taken to place batts or rolled insulation. I did it when it was cool enough to wear a white paper suit that covered most of my body. I would never consider doing it any other way in my case, now that I have done it. There were lots of obstructions that you may not have, so YMMV.

Bill

[Carlos Alvarez]

I keep reading that you need to first put some kind of dam around any ceiling lights and the vents all around. True? Or did you not do that? Which seems like more than half the work/time.

[Bill Space]

Good Point about the lights.

I installed a about 16 recessed ceiling lights, but they were designed for total cover by insulation, so it was not necessary to provide any airspace around them. Used LED lights, but the "cans" I installed were rated by wattage, not bulb type. Old style recessed lights would be a concern, and probably do require some airspace to be provided around them.

Lights mounted on the ceiling with only a junction box in the ceiling would not require any special treatment in my understanding, since heat is generated within the room and not in the insulated area.

Bill

[Carlos Alvarez]

I have recessed "can" lights all over the house. They are incandescent fixtures with LEDs in them now (house is 11 years old). So they are probably safe for me to cover, but if someone were to switch the bulbs back, it could be bad. Also I currently have cellulose insulation and wonder if I should just stick with more of that.

[Bob Bouis]

If your house is just eleven years old the can lights almost certainly have thermal overload switches to prevent them from getting too hot.