Ceiling Vent

[Gil Rubio]

I'm look for some input on my next project. I have some time off for the holidays so I want to install drywall on my ceiling.

I have a flat roof that sits on TJIs. Do I need to install any sort of ventilation up there? I plan to eventually heat the garage.

Thanks.

Heres a Pic from the inside.

 

[Stuart in MN]

Responses may depend on where you're located, and the climate - Florida probably has different requirements than Canada.

 

[f6john]

I would not use drywall for a shop garage ceiling. I would recommend a bi rib metal ceiling in white for light reflectivity. You can insulate detention the joist leaving an air gap at the top and then possibly install vent openings at either end of the joist run to get some cross ventilation .

 

[Gil Rubio]

Responses may depend on where you're located, and the climate - Florida probably has different requirements than Canada.

Good point, I should have clarified. I'm in New Jersey so we get a range of weather but no insane extremes. I will also be putting in fiberglass insulation.

 

[Gil Rubio]

I would not use drywall for a shop garage ceiling. I would recommend a bi rib metal ceiling in white for light reflectivity. You can insulate detention the joist leaving an air gap at the top and then possibly install vent openings at either end of the joist run to get some cross ventilation .

Thanks, I will look into that.

 

[BillK]

A lot of it is going to depend on how your roof is constructed too. The flat roof here at my business has about 6 inches of solid foam insulation under the roof surface. The ceiling is ribbed metal. If you have insulation above your plywood it might change the entire deal.

 

[Gil Rubio]

It's a spray on roof so I believe it has insulating properties. But other then that there's no foam. So its cunstructed of TJIs then plywood, and finally the sprayed on roof coating.

 

[Gil Rubio]

bump

 

[DGersic]

I wouldn’t put fiberglass or Sheetrock up there. When the roof leaks, Sheetrock turns in to a falling mess, and fiberglass holds water and grows mold.

If you’re going to insulate, do it with something impervious to water. Then ribbed metal ceiling, something that won’t be destroyed when it gets wet.

I’m in Illinois, have an almost flat roof on my garage. It drops about 8” in 20’. I used ribbed plastic roofing for the ceiling, ended with a gutter across the back wall. Had previously done Sheetrock, and had to clean it up, twice.


Sent from my iPad using The Garage Journal mobile app

 

[Chris705]

Gil - are you positive the roof has no sort of rigid insulation on top of the plywood? A spray roof as you point out would have little to no insulation value. Does the roof overhang the wall at top and bottom? If yes how much and would you be able/willing to install soffit vents at top and bottom? I don’t have any experience with a spray on roof where today’s single ply membranes typically have a minimum of a 20 year warranty.... any idea on if the spray roof coating is warranted?
I am asking because I would suggest a closed spray foam to deck & no ventilation if a long warranty exists, but if no warranty or only a 15 year warranty I would tend to advise you ventilate top and bottom and drop your ceiling down a couple feet if possible and add lose blown in cellulose or blown fiberglass on top of the ceiling leaving a void above the insulation so you can have an inspection hatch from below. What are your thoughts?