Ventilation suggestions Please!

[86Garage]

I thought it was a bit odd the rating looked like a generic engineering drawing and said that was the rating for 14 gauge. I ordered 12 gauge. Didn’t list rating for that but I would assume it’s more than 13lbs per ft.

 

[bluedog225]

Fiberglass batts weigh maybe 1 lb per sq ft. for 10”?

what kind of ceiling were you thinking?

 

[Firebrick43]

Fiberglass batts weigh maybe 1 lb per sq ft. for 10”?

what kind of ceiling were you thinking?

29 liner panel weights 0.59 lbs per square foot. R38 batt is around 0.6 lbs as well so both well under 2 lbs per square foot. The liner can span across the bottom of the truss on 4' spacing with fiberglass weight without issues if run perpendicular to the trusses so no purlins needed.

 

[86Garage]

Yes, that is the same thing I was reading. Thought about blown in cellulose which is slightly less weight. Installing a ridge vent and soffit vents? But the way these trusses are built the caroling is closer to 14 foot with 12 foot walls. So it’s higher than the soffit. Makes it kind of hard to install soffit vents.

 

[86Garage]

Fiberglass batts weigh maybe 1 lb per sq ft. for 10”?

what kind of ceiling were you thinking?

Steel 29 gauge

 

[racecougar]

I looked at the engineering drawing and it said the roof dead load was rated at 13lbs per sq. Ft. That was with 14 gauge tubing and I opted for the 12 gauge.

That is for the roof, not the BCDL.

 

[86Garage]

Can you tell from this sheet?

 

[racecougar]

Can you tell from this sheet?

Yep.

 

[86Garage]

I did read that number is different than BCDL. I found the following. Depends on who you ask I guess.

 

[racecougar]

A roof collateral load rating of "0" means the frame was not engineered to carry the extra suspended weight of a ceiling, risking sag or failure without reinforcement. Can you do it? Sure. Will it fall down? Maybe, maybe not. Is it advisable? No. Per the spec sheet, the building was not designed to carry the load of a ceiling, which is typical of that method of construction (tubular steel, "carport-type" buildings).

At this point, working with what you have, I'd look toward spray foaming the underside of the roof.

 

[86Garage]

So I am looking into this some more. Wish I would have known what I was doing before. By the time I add ridge cap vent, soffit vents, mineral wool insulation to help if it becomes damp. I might as well cut the roof stuff off and closed cell spray foam. I got a lot better price on it. But the guy said people with bubble up already use open cell usually. Houses put up a vapor barrier and open cell the inside before drywall. I assume the difference is they are wood and not metal.
I was thinking about closed cell directly to the roof, but what do you recommend for the side walls? Fiberglass batts then steel, open cell foam? In Middle Tennessee and I plan to both heat and cool the building.