Fire safety & lightweight ceilings

[d3ad1ysp0rk]

Hi all,

I've got a 24x24 that I have recently started finishing (R15 in the walls with 1/2" drywall). I would love to finish the ceiling, but the joists would not support the weight of drywall and insulation. The only solution I've thought of would be a beam to split the distance, which would add a few grand to the costs. This is still a possibility in the long term, but for now, it's out of reach.

I understand that foam board is not meant to be uncovered, and I am wondering if either the foil backed foam, or another solution may be safe, lightweight, and still keep some of the heat in? I figure anything is better than the open rafters I have now.

Here is a pic: http://i.imgur.com/aLoBfXv.jpg

Thanks!

 

[BlackTalon]

Might want to consider metal panels for the 'finish'. You could insulated above them.

I'm surprised your ceiling joists cannot support gyp board. It's pretty normal to design with allowance for ceiling/ hanging load. But they were designed only with enough strength for the roof/ floor above dead loads and live load?

 

[d3ad1ysp0rk]

Tough to say what it can support, but it definitely does not meet current code as is, so my fear is that modifying it in a permanent way would open me up to code/liability/permitting issues. I had a structural engineer come by months ago, but he was pretty awful and basically just ended up agreeing with my long term plan after spending an hour chit chatting.

I know the center of the joists are 1.5" lower than the edges.. and when I put a 15lb seat across two, it noticeably sags a little more.

 

[BlackTalon]

The pic is not the best, but it looks like the 'joists' are spaced up to 5 rafters apart, and it's a really long span (leading to the joists not being continuous). So definitely concur it looks dicey.

Trying to install anything supported by the joists will require adding a bunch of nailers or maybe metal hat channels that can be used for securing a cladding system. Going with metal hat channels and some type of sheet metal ceiling would by far be the last weight, although probably not the least expensive. But you might need to install more joists just to be able to install a hat channel system.

What about insulating up against the bottom of the sheathing to make a compact roof? That would typically be done with spray foam.

Also, did the structural engineer indicate if you could hang anything from the rafters above? If they have the capacity you may be able to install a suspended ceiling that is at/ below the joists, but is secured to the roof rafters.

 

[zmaxmotorsports]

How about hat channel across/between the bottem of joists?

 

[bzinsky]

You seriously want to do this regardless of drywall, I'm surprised it held up to Maine snow.

The town does not likely want to know about your garage structural repairs. It makes them liable, and your not putting lives at risk like a home. Just use some common sense. You don't need to spend a lot, but you 100% need to do some work regardless of the drywall. Luckily is pretty easy and cheap.

Here's a good picture to get some ideas.

Add a bunch of collar ties, but make them lower and beefier than in the picture.

You want to picture your roof and joists as a triangle and it's completely independent of the walls its resting on. Make the triangle strong, then you can do whatever you want.

A beam in the center is actually not even a good way, just an expensive band-aid.

 

[Bricen18]

I put up a 2x12 lvl beam up 33ft it was under 500 for everything. All of my rafters were sagging and were probably out by as much as two inches


I don't think the uncovered foam board would be an issue in a detached garage. Only if you are going to be sleeping out there.

Here is the only pic I had you can see the one end of ot in the top picture. There are more pics in my thread


Sent from my iPhone using Tapatalk

 

[d3ad1ysp0rk]

The town does not likely want to know about your garage structural repairs. It makes them liable, and your not putting lives at risk like a home. Just use some common sense. You don't need to spend a lot, but you 100% need to do some work regardless of the drywall. Luckily is pretty easy and cheap.

Liability falls somewhere if the roof/ceiling collapses, right?

Thanks for the image, I hadn't seen Purlin's before (hence why I'm approaching this all carefully, I'm definitely inexperienced). It definitely gives me another option, but I probably should still get the exacts figured out by a structural engineer if I move that route eventually..

 

[plow]

Drop ceiling tile?

 

[Jlbc212]

Make trusses as shown in Bizinsky's post. Temporarily jack up and support each ceiling joist to remove the sag. Eight feet in from each wall run a 2x4 up to the center of each rafter. Use plywood or another short length of 2x to attach the 2x4 to the ceiling joists and rafters. These are gusset plates. I would add additional ceiling joists so that there is a ceiling joist for each pair of rafters. Nail 1x3 strapping, 16" on center perpendicular to the bottom of the ceiling joists. This should give you the strength you need to apply drywall to the ceiling. You can insulate with fiberglass over the strapping before installing the drywall.

 

[Milton Shaw]

Nobody else has mentioned this but for a temporary measure just put a ceiling fan in to get the heat down to floor level. It would make a big difference for just a $100 bucks or so. You would also get the benefit of the heat buildup from solar on the roof shingles. It makes a big difference to get the heat down where you can feel it instead of 10 ft overhead.