Do I need a temp supporting wall?

[MikeC55]

In reference to this thread on raising garage ceiling (https://www.garagejournal.com/forum/threads/raising-garage-ceiling-questions.500414/), I'm also planning to remove the two 9' wide doors and replace with one 12' door centered on gable end. I read it many times that there is no load on the gable end, but am thinking there has to be some load from the weight of the materials that make it up. Would a post from concrete floor to existing ridge board be enough of a temporary support? Or do I need a temp wall (attached to top plate?). I plan to remove existing headers above garage doors and replace with 2 ply LVL for the new door, and bring the foundation up to meet the extended wing walls. The (double) top plate on the existing wall is not one piece and has slightly staggered splices at the center support between the 2 existing doors. Should I replace this with a full span top plate? It would seem that once the new beam is in, it won't matter.

 

[Bert_]

If the wall is sheathed with plywood or OSB I wouldn't get to worried.

 

[Rusted Nut]

Gable end trusses are not self supporting, like a standard truss; so yes it’s load bearing on the wall. However, probably not too much. As Bert said, if the gable is sheathed, probably not too much of an issue. If it were me, I would temporarily support it somehow. A couple of strong back braces @ 70 degrees both from inside and outside.

 

[MikeC55]

Thanks, guys. It's not a truss, just vertical 2 x 4s, that go from top plate to rafters, sheathed with 1/2" plywood and plastic cladding on outside. Can you describe strong back braces? I've seen in some videos, they'll make a T-shape out of 2 x 4s (edge connected to face). Any thoughts on how many supports? Maybe one pair in middle and another pair mid-rafter each side?

 

[Rusted Nut]

Yes, strongbacks are 2x4 in a tee. Other thing you could do is remove one of the existing headers, and then install new header at an angle with some temp posts, then slide it in knocking out the other single header.

 

[Jackfre]

If you have to ask, the answer is yes.

 

[MikeC55]

That's a good idea on putting new header in.

 

[bdbecker]

Minimal cost and time, but peace of mind. If it were my project, I'd rather do it and not need it than wish I had.

 

[The Cobbler]

probably not needed, but If you like to err on the side of caution, put a bit of temp support in

 

[KenC]

In reference to this thread on raising garage ceiling (https://www.garagejournal.com/forum/threads/raising-garage-ceiling-questions.500414/), I'm also planning to remove the two 9' wide doors and replace with one 12' door centered on gable end. I read it many times that there is no load on the gable end, but am thinking there has to be some load from the weight of the materials that make it up. Would a post from concrete floor to existing ridge board be enough of a temporary support? Or do I need a temp wall (attached to top plate?). I plan to remove existing headers above garage doors and replace with 2 ply LVL for the new door, and bring the foundation up to meet the extended wing walls. The (double) top plate on the existing wall is not one piece and has slightly staggered splices at the center support between the 2 existing doors. Should I replace this with a full span top plate? It would seem that once the new beam is in, it won't matter.

I would screw or nail a 2xsomething to both top plates and the vertical gable 2xs. Then put a temp brace at the center of that added 2x to the floor, probably 2 2x4s in a tee.

The something above could be a 2x6 IMO but use larger if it makes you feel safer.

 

[MikeC55]

Thanks, Ken. For adding 2x to the vertical gable 2x4s, do you mean on a diagonal (like an X) or horizontally? (like this?)

 

[Dagny]

how close is the next truss.

 

[NUTTSGT]

Not sure exactly where you are at with the work you mentioned in the other thread but your place has a ridge beam and rafters, I would definitely put in something to support the ridge beam while you removed it's support.

If you had trusses 24" OC, it was all sheathed and remove/replace on the same day, I would probably forego the support structure.

 

[cgrutt]

The theory says load will be supported by the outside walls. If it were mine I'd at least try to put a post under ridge beam near the end where you're working. I'd also consider putting a 2" cargo strap between the top plates to prevent walls from spreading after you remove the headers.

 

[MikeC55]

The next pair of rafters (not trusses) in from gable end is 16". The ridge beam does not extend all the way to front of garage, (see red lines in side view diagram post #11), but probably helps support the 4 feet of ridge board continuing to front. I do have 2 x 10 rafter ties on the 2nd and 3rd pair of rafters form the front wall (also shown in same diagram). The ridge beam supports will not be removed to make the garage door change. I know it's a bit unusual that my ridge beam doesn't extend full depth of garage; it needed to be something I could install from inside the garage mostly by myself. I have another thread on that here, if interested (https://www.garagejournal.com/forum/threads/raising-garage-ceiling-questions.500414/). Full depth ridge would have required punching hole in gable and sliding in beam from outside, which would require a crew or a crane (I preferred a 'stealth' approach, if you get my drift).

 

[Leaflessshadetree]

I'd put in a temporary post.
Taking out 2 9' doors and adding in a header You will be reframing (rebuilding) the front wall.
Why not go with a standard 16' or even an 18' wide door?

 

[Hank11]

As you figure out how to defy gravity with your new header across the opening, think about stiffening the opening in and out. That will make your door seal lots better and provide a stiffer support when it is opened and closed. Even more so if you have an opener on it.

Some diagonals running across the trusses will get you there. Like a diamond shape.

 

[MikeC55]

I did think about going with a wider door, but with the (2 post) lift centered in the garage, I wouldn't be able to park 2 cars in there (easily) and the extra wall space of wider wings is more useful to me. As to helping stiffen the in/out direction of the gable wall, I do plan on adding blocking between the gable wall and rafter ties back to the 4 ply LVL rafter tie/ridge beam post support. The LVL is tied together with 3 rows of Flatlok thru fasteners at 12" OC.

 

[KenC]

Thanks, Ken. For adding 2x to the vertical gable 2x4s, do you mean on a diagonal (like an X) or horizontally? (like this?)

Sorry for the delay. Horizontally.

 

[MikeC55]

Thanks, Ken.

 

[MikeC55]

Another related question; I’m trying to understand what I most likely have for foundation under the front wall (gable end with doors) of this garage. The apron is in good shape, no cracks, so I really don’t want to demo it just to find out what’s under there. As per my plan above to convert to a single, 12’ wide door, I’ll be extending the ‘wings’ on each side of new door to 6’. I'm planning to pour concrete to bring the wing wall(s) foundation up to the same level as the rest of garage foundation. The existing foundation is only about 4" higher than floor slab, so we're not talking about a lot of concrete. The existing foundation is also just open concrete block, with a 2 x 6 plate J-bolted to block and then wall constructed on top of that (they sold blocks with cast in j-bolts back then - see https://www.garagejournal.com/forum/threads/cement-disbond-from-block-foundation-wall.504110/ , post #24). I'm not planning to demo the apron, but pour on top of it for the wing wall foundation. The apron has no cracks, but I'm going to drill a few holes to get an idea of how thick it is. I'm assuming the foundation block runs underneath this portion of the apron, since the 2' wide center portion of wall, (between the existing 2 doors), supports the ends of the existing headers (see post #10). Without demo-ing the apron, I'm not sure I'll be able to verify this by simply drilling holes (other than the drill bottoms out before punching through). I'm not too concerned as there is minimal load on gable end wall. Or maybe I should demo at least the areas where the new single door header ends are supported (to make sure there's more than just 4" thick apron under them). I would think it would have been more trouble to build an interrupted foundation for the gable end than just running the same footing and block the whole length. Any thoughts on the likely construction under apron?

 

[Rusted Nut]

Most garage door openings do not have a footing or foundation wall under the garage door openings.

 

[Innovate1]

Most garage door openings do not have a footing or foundation wall under the garage door openings.

That's a pretty sweeping generalization. Both buildings here have footing and foundation wall all the way around including under the OHD openings. If it's slab on grade with no foundation then that is the same all the way around too. But those poured concrete. Not familiar with block foundations so I suppose some might skip under the openings.

 

[coldh2o]

Most garage door openings do not have a footing or foundation wall under the garage door openings.

Are you building somewhere that frost is not a concern? I've never seen a garage door opening that doesn't have a full footing and foundation below it. Even on a floating slab with no foundation, there is full structure below the door opening.

 

[Rusted Nut]

For the OP’s sake, hopefully I’m wrong. All my building experience in the Pacific Northwest, and I’ve build hundreds of houses, none of which have foundations under the garage door openings. Regional thing I guess.

 

[Fav Onefour]

I've seen door openings done with and without footings in our area.
There doesn't seem to be any rhyme or reason to the practice. A few years back, I had an opening that looked like no footing across the opening. The doorway had a normal seam between the pad and apron with good compacted fill under everything. We were replacing the pad, apron and running hydronic snowmelt. That meant removing more base to install insulation. We ran into a footing across the opening under a couple inches of base.

I'd check everything with a ground probe just to verify. It's easy and quick. You'll also be able to verify how deep if there is a footing.

 

[MikeC55]

Hi Guys, thanks for the responses. Frost/snow ice is definitely a concern here in CT. I just drilled a few 1/2" holes and the good news is that concrete in the area in question is 8 & 1/2" thick and below that something softer, but still drillable. Stuck the bore scope in there and I'm pretty sure I'm looking at CBU (fine-grained, darker grey). Drill bit length ~ 11". So, I feel pretty comfortable building the wing walls on that. I plan to use some 5/8 diameter concrete expansion anchor-type threaded rod in the apron, long enough to go through the new pour and secure wall base plate.