Garage has basically no joists

[Geo.bre.dc]

I’m wondering if the garage that is lacking joists will continue to stay standing. It has a an addition to the side that has 2x6 rafters mitered in to existing roof. Old roof is 5/12 and the addition has corrugated plastic and is 2/12. There’s no signs of leaning and everything is plumb, surprisingly. I beefed up the corners and sistered in a bunch of 2x6 to kind of form posts at the corners. I was thinking I could run a joist across at least at the end of the garage opposite of garage door. I’ll attach some pics. Old garage framing is a true 2x4.

 

[Geo.bre.dc]

PS I found a post of mine from 2 years ago that shows an interesting back story. All DIY, ongoing project for myself.

 

[kaymccampbell]

The cross ties you have in there look just fine. Do you want ceiling joists to hang a ceiling from?

 

[Geo.bre.dc]

Absolutely don’t care about the ceiling. No desire to insulate. If it’s that cold I’ll crank the propane heater and fork over the money for an extra tank. It stays about 60 when it’s below freezing and I crank the heat. I’m fine with that.

 

[Geo.bre.dc]

I wanted ceiling joists out of concern that the walls could spread over time. I cut a template of a rafter that would grab the top plate and **** up nicely to the collar tie. Figured I could add a gusset where they join and connect the walls that way…but could be a stretch.

 

[rayra]

I wanted ceiling joists out of concern that the walls could spread over time. I cut a template of a rafter that would grab the top plate and **** up nicely to the collar tie. Figured I could add a gusset where they join and connect the walls that way…but could be a stretch.

Collar ties does the same thing, as long as the rafters are properly attached to the top sills. There shouldn't be enough flex in the rafter tails below the collar ties for it to matter.
You could hang / mount a few iron pipes across if it still bugs you, and wind up with lower places to hang things from.
Or just add joists across atop the top sills. Attached with hurricane ties or similar bracket.

 

[dutchgray]

Looking at your pics it was probably fine as built, minimal but good enough for its time, not up to current standards.
Your added collar ties and corners do add considerable strength.

 

[Leaflessshadetree]

Looks like it had 1 ceiling joist (aka rafter tie) at the top plate that was fine for how many years. You added a bunch of raised rafter ties and collar ties with 3 nails in each end. Should be fine.

 

[jack stand]

All the new lumber is in the right place and is doing its job.
Relax.

 

[firebirdparts]

It's fine.

 

[pbon]

Not uncommon to have just a few collar ties in a small garage. They are not joists — there is no 2nd floor to support. The just hold the long sides of the building to each other to help keep the building square. Add some more if the building has shifted a little or if you want to store stuff on top of the collar ties.

 

[TRWham]

There is frequent confusion here regarding the function of these 3 different things:
1. Collar ties
2. Rafter ties
3. Ceiling joists

Collar ties only hold the roof down against wind load and don't do much at all to stabilize the walls.

Rafter ties are used in a roof system that has a non-structural ridge board. In this system, the rafters are in compression and carry the roof load to the walls but because a component of that pushes out on the walls, rafter ties in tension are used to resist that thrust. Rafter ties may be only every few feet in older codes but recent IRC calls for a tie at every rafter.

If a building has a structural ridge beam posted down to carry the roof, it needs no rafter ties but will still need collar ties or straps to resist uplift. If the roof system is trusses then you need no (separate) rafter ties, but the bottom chord of the truss serves that purpose.

Ceiling joists carry the ceiling deadload and maybe storage above. Rafter ties might also function as ceiling joists, but then they will be at each rafter.

A structure might have both ceiling joists and rafter ties if the ceiling joists are not perpendicular to the ridge for some reason.

Ceiling joist might also be floor joists, but then they have little to do with the roof.

 

[captain14]

My 10x20 brick garage has basically the same roofing structure as yours. One joist runs side to side at the midpoint. My garage was built circa 1939-40’s.

 

[CraigStu]

Wow, they sure had a lot of faith in the top plates in those walls didn't they. And they are a single top plate. I just can't imagine a 20ft long wall tied to the other 20ft wall at the ends and one point in the middle. But it is still there so it sure proves that it works. I would probably do pretty much the same as the OP has done if I owned it.

 

[kbs2244]

the cross ties will work fine if the joint joining the rafters to the walls is solid

 

[Geo.bre.dc]

inspecting the wall and thinking how to reinforce, for storage cabinets maybe?

 

[mikedodge]

It doesn't look that surprising. Between the framing it does have and the plank walls it had decent support. The beams and cross bracing you added was a good idea tho.

 

[Geo.bre.dc]

How much of the framing remaining straight and upright depends on the sheathing- whether planks or something like OSB?

 

[cmandp]

Yes sheathing or diagonal bracing gives the wall all of it's shear (resistance to racking) strength. I'd think about sheathing what was the outside portion of your rebuilt wall there as from what I can tell it is still structural; it's holding up your lean-to there.

 

[Geo.bre.dc]

Thanks I really appreciate the wisdom and advice.

 

[FMB4]

Yep, put your garage to use as is. You're good to go imo.

 

[Geo.bre.dc]

so do I worry about shear force?

 

[firebirdparts]

so do I worry about shear force?

I say yes. You really don't have any strength now against wind. It wouldn't cost a huge amount to make yourself feel better about that.

 

[Geo.bre.dc]

I added some cross bracing from top to bottom plates at two sections of the wall because it was supposed to be really windy last night. It put my my mind at ease.