Ideas for insulating ceiling

[Schmitdy]

Hey guys,

Long time viewer, first-time poster.

My father's 60th birthday is coming up and my brothers and I decided that we're going to redo his garage for his birthday while he is out of town.

One of the first things we want to do is insulate the garage that he uses to restore classic cars. Right now the garage has no insulation (besides the walls) and has quite tall rafters.

From my research, I understand that pretty much all insulation needs to be covered by sheetrock or wood. However, not sure how feasible that would be in this garage. Is there any insulation that can be used without the need of protective sheetrock?

I'm open to all ideas, we are trying to do this on a budget, but I'm open to all types of ideas. We just want it retain some heat when he is using his electric heater. I have attached some photos of the garage.

 

[btdobie]

Closed cell spray foam does fine when exposed. You could spray a couple of inches on the under side of the roof. There are a couple of downsides to this
#1 is cost
#2 is if the roof leaks closed cell foam can trap moisture in the roof deck leading to rot.
#3 ice damming could be a possibility depending on the circumstances.

 

[acer66]

Code might mandate drywall but if not the cheapest and fastest way I can think of is fiberglass covered with thin lauan sheets and if the joints are an eyesore use some 1x strips to cover them up.

 

[Schmitdy]

Have the sheets be the barrier between the insulation?

 

[James-W]

I would not insulate the roof. The roof is real high and the warm air from the heater will end up by the ceiling where it won't do your dad any good.

To do your dad a good deed and warm up the building to make it comfortable for working, you would need to lower the ceiling. If you lower the ceiling, and insulate it, you will trap the warm air from the heater down lower to the floor where it will do the most good. It will cost more money to do it this way, but your dad will be warmer and the cost of the heat should go down since the heater won't have to heat as much space.

 

[88thunder]

What about 2"/3"/4" rigid insulation cut to a friction-fit-width and forced between the roof rafters? But not all the way to the battens, so as to create an air gap?

 

[acer66]

I would not insulate the roof. The roof is real high and the warm air from the heater will end up by the ceiling where it won't do your dad any good.

To do your dad a good deed and warm up the building to make it comfortable for working, you would need to lower the ceiling. If you lower the ceiling, and insulate it, you will trap the warm air from the heater down lower to the floor where it will do the most good. It will cost more money to do it this way, but your dad will be warmer and the cost of the heat should go down since the heater won't have to heat as much space.

This is what I did, I was fortunate enough that I was able to move the rafter ties higher so I could have a 10’ ceiling.

A lower flat ceiling is also easier to work with and while you might need some extra lumber you will need less insulation and whatever is required to cover it.

 

[earlybirds]

I used 2" polyiso closed cell rigid insulation 4x8 sheets that I special ordered from Menards. They have a special silver colored fire rated coating on them so no drywall is needed. I screwed them to the bottom of the perlins in my pole barn. This left 3 1/2 inches of ventilation between the insulation and the metal roof sheeting. Perlins are on top of the trusses. I have 3 ceiling fans to keep the heat down where I need it in my 30x40x12 shop. It works great! After 3 years of winter heating, I wouldn't change a thing.

 

[QwikKotaTx]

I am going to use a product called Anco TextraFINE. It is fiberglass insulation sealed inside a vinyl layer. It has flaps on each side to attach to framing and is white for helping reflect light. You have to call them and find a vendor in your area and typically it's custom made.

https://www.ancoproducts.com/textrafine

 

[acer66]

I used 2" polyiso closed cell rigid insulation 4x8 sheets that I special ordered from Menards. They have a special silver colored fire rated coating on them so no drywall is needed. I screwed them to the bottom of the perlins in my pole barn. This left 3 1/2 inches of ventilation between the insulation and the metal roof sheeting. Perlins are on top of the trusses. I have 3 ceiling fans to keep the heat down where I need it in my 30x40x12 shop. It works great! After 3 years of winter heating, I wouldn't change a thing.

Never heard about that but I will check that out for my next project.

 

[nmk_61802]

I used 2" polyiso closed cell rigid insulation 4x8 sheets that I special ordered from Menards. They have a special silver colored fire rated coating on them so no drywall is needed. I screwed them to the bottom of the perlins in my pole barn. This left 3 1/2 inches of ventilation between the insulation and the metal roof sheeting. Perlins are on top of the trusses. I have 3 ceiling fans to keep the heat down where I need it in my 30x40x12 shop. It works great! After 3 years of winter heating, I wouldn't change a thing.

Pretty certain this is incorrect information. IBC still requires a layer of non-combustible material (gypsium) where attached to living space. The spec's for the JM Polyiso w/ AL facing only say that it does not melt like other foams and they show it having a low flame spread rate. For a detached garage it doesn't really matter.

Also with a non-permeable insulation such as Polyisocrate, air space is not required provided you use enough insulation to isolate the interior from the exterior. In my climate zone R-20 provides enough insulation to keep the two areas separated.

https://www.finehomebuilding.com/2011/07/14/a-crash-course-in-roof-venting

 

[Schmitdy]

Okay so we're looking at possibly lowering the ceiling by installing some type of wood or sheetrock on the or below the rafters. Then installing the insulation on top of that.

 

[CombatNinja]

You're on the right track. That rigid foam is typically R6 or so per inch. Those 2 3/4" will only get you in the neighborhood of R16. Factor in imperfect fitment for air gaps and the fact that the installation above leaves all the framing open for thermal bridging and you will end up at less then R12 in the end, not what you want for a ceiling in a Wisconsin winter.

You need to get some kind of ceiling in and get some nice R38 in there with full coverage, even R60 if you really want it to get snug. The ceiling is vastly more important than the walls when it comes to heat loss due to the chimney effect. Your Dad is getting to that age where the cold will start impacting his ability to get out there and use his garage if it hasn't already. You lot sound like a good group of sons that want to do something nice for the old man. If you're going to put the effort and expense out, do it right. None of you are going to sit around over a whiskey the day you bury Dad and lament the extra money or time it took to make Dad's shop warm. I bet you will talk about all the good times you guys had in the garage though.

 

[tom86951]

How about old fashion fiberglass insulation (pink owens corning, etc.) hidden by corrugated metal? Both are pretty cheap and the result looks pretty cool. And that ceiling is begging for it.

 

[SeanH]

My rafter ties were 16" OC in my old garage. I just used craft faced rolls of insulation, and stapled them to the underside of the joists. Then I just put some pieces of OSB on the underside in a few spots to keep them from falling out. I did not cover the entire ceiling with OSB, just a portion. It wasn't pretty but it did the job fine.

Prior to that, I make sure I had soffit vent chennels and ridge vents, to ensure proper airflow in the attic (thus preventing ice damming and ensuring longer roof life).

 

[matt_i]

That looks to me like it would be well served with the thin metal panels and then place loose fill on top of that. However I think some beefing of the bottom chord would be in order, if you could place single-piece 2x10s between the existing 2x4s (?) then I think you'd be in a better place.

 

[Notgrownup]

I would make sure the soffit are in place and install air baffle foam dams like in Sean’s post and install OSB on the ceiling and blow in cellulose insulation. Gotta let the attic breathe somehow right?

 

[CraigStu]

Not that it isn't something to think about anyway but code in N. Va. required my add-on garage to have the fire resistant drywall on the wall that used to be the outside of the existing attached garage. All the rest of the walls and the ceiling could be normal drywall. In your garage, because it doesn't have the usual trusses on 24 inch centers lowering the ceiling could get interesting. I would look at that idea though. Combine it w/ any of the metal sheet products because they are rigid and very light weight and then just use any standard insulation on top of that. The style that tom86951 is just one style. My brother had something like this installed on the walls and ceiling of his garage and he really likes it. Do it in white and the shop will be 50% brighter than it is now.

 

[Whitworth]

Strapping 16 inches oc.

Rigid foam board screwed to that.

More insulation (fiberglass batts) on top of that.

Drywall the ceiling if you wish.