Strengthening top plate butt joints

[JHZR2]

My new garage has ten bays with sliding doors. Because of the width of the building, the top plate comes together in a butt joint many times. Some are over the unsupported span where the door is.

Here is an example:

One of them is opening up a bit because it’s midway in a 10’ span.

Any recommendationson how to best synch a joint like this up? I’m thinking to jack up a bit from the lower side, then drill through both and bring them together with a bolt with as fat and wide a washer as I can find. Maybe also attach it from the side with a Simpson strong tie connector of some sort.

Any other recommendations? Not a lot of room to work.

 

[thastinger]

That has been that way for what?...100 years? That joint isn't separating, they cut those with hand saws...that is how they looked the day they went up.
I have a 125YO house, I recognize the construction.

 

[Amkeer]

Leave it. That is what a 4x6 or 4x4? That is a work of art.

 

[OppositeLocK]

A garage for 10 cars? Do you live in a mansion?

 

[JHZR2]

That has been that way for what?...100 years? That joint isn't separating, they cut those with hand saws...that is how they looked the day they went up.
I have a 125YO house, I recognize the construction.

that one is good.

further down the line there is one that is in the middle of the door/bay opening, and is opening up for whatever reason. Not a ton, but enough to notice it. It’s making the sliding door track become crooked. So I’d like to cinch it back.

 

[Donald]

Steel I beam

 

[Strokenmerc]

Can you verify with a straight edge or laser how much it has sagged? If you do attempt to add additional support, I would suggest a steel plate on both sides with thru bolts.

 

[supton]

I wonder if flat metal plate, two of them, put into it with large bolts, would shore it up. Metal being better able to resist deflection.

With 10 bays I'm guessing you could just avoid this one bay for now? I wonder if you could start with getting a jack under it, and slowly lift it back into place. Not sure how fast you want to move/lift the beam, maybe a bit over several weeks. Might as well start that process of jacking then.

I almost wonder if some measurements elsewhere ought to be taken first, then compared after jacking. Maybe something else shifted, causing this problem, and jacking might show where the weakness is. I'm guessing that is not the case, that this slow shift has been going on for 100 (?) years.

I'm thinking any tie between the two beams may need to be through both sides, like in double shear, otherwise the wood may be apt to do what wood does (deflect, twist, bow).

 

[AZjeff]

Get a sheet of 3/4" exterior plywood and cut plates out 4' wide and the height of the beam. Take the extra junk off the sides of the beam as seen, jack it up if necessary and nail the plates on each side. No need for drilling thru holes, steel plates, etc. Good for another 100 years then someone else can worry about it.

 

[supton]

Get a sheet of 3/4" exterior plywood and cut plates out 4' wide and the height of the beam. Take the extra junk off the sides of the beam as seen, jack it up if necessary and nail the plates on each side. No need for drilling thru holes, steel plates, etc. Good for another 100 years then someone else can worry about it.

I wasn't sure if it'd just twist if not all the way through. Nail vs screw though? Wouldn't screw clamp better?

 

[RhondaHonda]

I wasn't sure if it'd just twist if not all the way through. Nail vs screw though? Wouldn't screw clamp better?

Nails resist the shearing better. How old is this garage? I’d like to see a pic of the sliding doors/entire setup. 10 bays is awesome.

 

[AZjeff]

I wasn't sure if it'd just twist if not all the way through. Nail vs screw though? Wouldn't screw clamp better?

If the joints aren't twisting now making them stronger isn't going to make them suddenly twist. This wood is dry. Some construction glue behind the plywood wouldn't hurt.

Think about the diameter of a screw shank vs a nail shank and the forces in your application as mentioned above.

 

[PimTac]

I like the plywood idea. ¾ “ would be the best choice. Personally I would go with lag screws versus nails. Make sure you go well beyond the splice on both sides. When jacking up go just a tad higher than level. The beam should settle back to a level position after the Jack is removed and your reinforcement is in place.

Is that a metal bar at the forefront with the 2 square head nails?

 

[supton]

Yeah, I was thinking if a plate was only on one side, then it might twist. Plates on both sides, no twist.

Makes sense on screws, although as PimTac says, a lag would be better yet. I still think though that a thro-hole bolt is best, all thread or whatever. This is BITOG, if it ain't overkill then it ain't enough.

 

[JC1]

Without seeing a larger picture sounds like you should sister up those joints. Looks like you have obstructions in the way, is that a metal plate of some sort attached? Lag screws may be a good option if you can only access the joists on one side.

Did you check the structure with a 6 ft level for sags in the middle?

 

[PimTac]

Yeah, I was thinking if a plate was only on one side, then it might twist. Plates on both sides, no twist.

Makes sense on screws, although as PimTac says, a lag would be better yet. I still think though that a thro-hole bolt is best, all thread or whatever. This is BITOG, if it ain't overkill then it ain't enough.

I agree, a bolt all the way through with washers would be ideal. I don’t know if he has access to the other side of that beam.

I did something similar with bolts on a smaller support. It held fine for years till I moved and I suspect it’s still there.

 

[JHZR2]

Without seeing a larger picture sounds like you should sister up those joints. Looks like you have obstructions in the way, is that a metal plate of some sort attached? Lag screws may be a good option if you can only access the joists on one side.

Did you check the structure with a 6 ft level for sags in the middle?

Do you mean along the rafter tie?

This is a very simple framed structure. Nothing but sill plates, studs, top plates and rafters. On the backside (no doors or windows) the top plate is all one piece of ~4x4. On the front, where the doors are, its more like 4x6. But not everywhere is really big timber construction.

The backside is where there was in the past termite damage along the sill plate. Most (90%) of the studs are still fine and look to be termite free. But a decent amount of the sill plate is gone. In some places, studs were hanging, in others they were on solid plate, but I cut them off and sistered with treated 2x4 after grouting in J bolts and setting a new sill on top of a foam barrier...

So its quite possible that the structure is tilted somewhat in some places. But overall it is "square".

The issue in the case I provided in the OP, is that the 4x6 in the spans along the sliding doors (the metal bar in the picture is the interior sliding door, each two bays have doors that slide to overlap each other one on the outside of the building, the other on the inside of the building, if that makes sense. Since these spans are around 10ft wide, there is no other support, and the beam supports a few roof rafters, plus the weight of the door. That weight, other twist or whatnot, has caused one of them to open up, such that it looks like there is a bit of "sag" in that span. Overall the front side is very sturdy. There are a spot or two where some of the vertical 4x6 may be a candidate for replacement, but there's no signs of termite damage like on the rear.

 

[PimTac]

Now it is starting to become clearer to me. Pictures sometimes don’t convey the total idea.

Are these sliding doors heavy? The reason I ask is that if you look at that picture the end of that rail coincides with the overlap joint of the 4x6. In reality your door is supported by a 4x3 and thus the sag. The wood must be good stuff. Today’s wood would not handle that as well.

That joint needs to be jacked up back to a flush fit and if possible tied together with a metal strap or the plywood but I’m guessing the clearance for the door is going to interfere here. A metal strap should not only be on the face of that header but wrap over the top and bottom as well. I say metal because that might be the only thing that would fit and allow the door to slide.

Just a thought.

 

[JHZR2]

The doors are definitely heavy. Theyre made of 1x stock for the front frame, and tongue and groove stock everywhere behind. And yes, the tracks are attached to this top plate/beam, so it will bring it down.

I agree that jacking the low side up slowly will be good. I think there’s enough space for at least a metal plate or a plywood sheet on one side. Not sure Ii can access the other. I was thinking it may be more viable to put something along the bottom, and bolt through the joint, upwards. Have lots of interfacing area on either side of the joint.

 

[JHZR2]

So I decided the other day to do the whole sill plate on the back, except the first maybe 10 feet which was solid. Ive been moving along bit by bit, I guess I’m about 50 feet in. I have one section where the top plate had termites. Very abrupt end on the one side, though they did jump from plate to plate on the other side, by about three feet.

This was the worst section of the entire 120 foot long building, these 12 or so feet. The top and bottom were rotted, and one whole stud. All replaced.

I cut out some of the top plate on the back. It’s not quite 4x3, width by height. Close enough that two 2x4 can be used instead. I cut out a similar joint to what is used all around the garage, and put in the new lumber. It would have been more of a craft to fit a 4x4 in there, but we didn’t want to take the time to go out. I think this will do fine...