16' Header Fishplate

[Gus_Mahn]

My 15 year old garage is 24'x36' with a 9/12 pitched roof (gabled on short sides). It has a 9' door and a 16' door on the long side. There is no floor over the 16' door, but the header (2x12 plywood sandwich) has sagged about 1.5".

I know it's not an ideal repair, but I intend to lag bolt a 3/8" x 12" x 16' steel fish plate onto the inside of the header after jacking it up. Does anyone have any suggestions for size, number, and pattern of lag bolts? I'd think that the majority should be to the outside of the 12" depth of the plate with an occasional bolt on either side of the neutral axis (horizontal centerline).

 

[twostory]

I would talk to a lumber yard that sells LVL beam. Tell them what you have, they will run the numbers through a program that will tell you what size LVL beam(s) you need for your header.

Then replace the old sagging header with the proper size LVL header and your problems are solved.

I do not think a fish plate is the best solution (if it works at all)

 

[bigdav160]

It's called a "flitch" plate and it will work fine.

While I'm not an engineering, I'd through bolt it, in a zig-zag pattern, about every 3-4 inches.

 

[Gus_Mahn]

I spoke with the local structural steel place. He was very familiar with doing this job. He suggested 3/8"x11" plate. He will cut it to size and drill the holes for $250. I ordered it and have a screw jack under the header. I thought about notchin the header for C-channel turned into the header, but he said this will fit my needs fine. It's more cosmetic than anything. Other than the roof/ceiling, there is no storage in that area of the garage.

 

[kbs2244]

I would use a bridging piece between the screw jack and the header.
Kind of like an inverted pyramid.
That will spread out the force and avoid any chance of splitting the header.
A 4 foot piece of 4x4 should work.

If you keep the jack on the ground and use a post between it and the header be sure to have everything plumb and level.
You don’t want it to “kick out” under load.

 

[CraigFL]

I would jack it slightly more than level so it will settle to level when you take out the jack. And get out your air wrench or impact to tighten all those lag bolts...

 

[rieferman]

I would jack it slightly more than level so it will settle to level when you take out the jack. And get out your air wrench or impact to tighten all those lag bolts...

Having lifted a 2 story, 100 year old barn, I'll say +1 to this one for sure.

 

[Gus_Mahn]

Thanks for the replies. It's within 1/2" of the original height from 1 1/2"sag. I'm hoping to get 1/4"-3/8" over the original height in about a weeks time. There is a 3' 4x4 on the top of the jack at the header. For sure on the impact! It's getting hot here, and I don't plan on doing 40+ lag screws by hand.

 

[Gus_Mahn]

Picked up the plate, and there are only 10 holes total. Four are 1.5" from edge (bottom) and six are on the other edge 1.5" from that edge (top). Essentially the holes are on 48" centers! The top edge has extra holes, so the holes are staggered on the top and bottom.

I did some reading online. From what I gathered, they were using 1/2" bolts every 20" on a smaller header with less load. I was thinking about drilling holes every 16" before I put this thing up. It will be hard to drill another 20 holes with the thing in place. No rental place offers a magnetic drill press around here.