Replacing section of sagging support beam

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  #1  
Old 07-18-16, 04:50 AM
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Replacing section of sagging support beam

Folx,

It is an A-frame, around 60Y. 2 floors, no basement/crawl space. Side bonus - ground level always cool ! Ground level is poured concrete floor/cinder blocks, the rest is wood.

Have a sagging floor on 2nd floor, may be 2" sag over 12' run. Nuisance & eye-sore & creaks galore. Traced it to sagging support beam on the ground floor. Started process of gradually leveling it with jack posts, in preparation for replacing it.

I have a support beam that is a staggered (!) sandwich of 5 of nailed 8x2, runs the length of the house.
The boards are may be 14' long, for total span of may be 24', supported in the middle, so no wonder it started sagging. Literally, the sagging section has only 2 (!) of continuous 8x2 supporting it.

1/2 of the house is nice and level, seems to be that way because in addition to the beam, that section also has a load-bearing wall (not sure if they designed it to be load-bearing, or it just came out that way as they went about walling up the ground floor).

Plan calls for leveling the sagging section. Then I'd place 4 of 9 1/2 LVL x 14' on the floor under the old beam and build supporting walls 2' on both sides of the beam (new LVL boards have to be pre-placed there first, otherwise I wont be able to get them in .

I'd then replace the existing load-bearing jacks (badly rusted) with news ones, of higher rating.

Remove the leveling jacks and cut out the sagging beam section. Install the new beam, one board at a time. One end would fit into the existing cutout in the cinder block wall (shims). The other end I'd support with a new jack post. Drill through and sandwich with 1/2 threaded rod, every foot or so.

In the end state, instead of one long and crooked and weak support beam, I'd have 2 sections, each spanning about 12' - one of old 5 of 8x2 and another one of 4x 9 1/2x2 LVL.


Each would be supported on one end by sitting inside of the pre-existingcut/notch inside of th e cinder block wall and on the other end, 16,000# jack posts ( 1/2" steel plates on top/bottom).

How does this sound ? I am a handy type, but havent done heavy structural work like this before and wanted to bounce it off the collective. Any gotchas to be aware of ?
 

Last edited by r1111; 07-18-16 at 06:21 AM.
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  #2  
Old 07-18-16, 06:26 AM
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You didn't mention the length of the floor joists being supported by your beam so we can't confirm that the 9 1/2" LVLs will be enough. The tables are also different depending on whether or not the joists being supported are continuous or not. Also, an 8" beam width is a bit unusual. In my area 5 1/4" wide is more common containing three 1 3/4" wide members.

You mentioned rusting support jacks (plural). How many jacks do you have and where are these jacks located? It sounds like your beam would have only one post or support column in the middle and supported by walls at each end.
 
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Old 07-18-16, 06:49 AM
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- The joists are about 11' on each side of the beam, in 2 sections (not continuous - so I will need 2 supporting walls )

- I hear about LVL being exceptionally strong, but not sure exactly how strong. So 4 of them will be an overkill ? I'd rather be safe than sorry

- the existing beam is supported by 2 old jack posts, may 2 feet apart from center point and the ends rest in the cutouts in the cinder block wall.

There are no plates atop of jacks, outside of the thin metal plate they come with . Those are bent way out of shape and dont even support the entire 5 boards, may be only 3 in the middle. The bottoms have no plates at all, they sit atop of exposed floor concrete and do show signs of rusting.
 
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Old 07-18-16, 06:54 AM
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http://www.doityourself.com/forum/el...-pictures.html

I think it would help to see a floor plan, just a sketch will do.

So 4 of them will be an overkill ?
Without going into specifics of sizing, a single LVL is capable of carrying tremendous loads.
 
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Old 07-18-16, 07:49 AM
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Quick & dirty, but I hope it explains the situation

I have placed 2 new jacks where the word "sag" is and started process of slowly leveling the floor.

The joists are not exterior-wall-to-exterior-wall 1-piece joists, but 2-piece instead.

The existing jacks are about 2 feet apart

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Old 07-18-16, 08:07 AM
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This may only be your drawing but you're showing a joint without a post underneath it; have to support every one of those.
 
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Old 07-18-16, 08:10 AM
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So I should add another post, right under where the remaining section of the old beam meets the new beam ?

Should I attempt to the join the halves too, with say a metal plate ?
 
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Old 07-18-16, 11:38 AM
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I see a problem with your plan now that we can see the drawing.

Should I attempt to the join the halves too, with say a metal plate ?
No metal plate can fix this. I commented the LVL is very strong. That's only if installed with both bearing ends installed correctly on a bearing surface, and at the same time installed so that the beam cannot rotate. The joists also need to be hung with the appropriate connecters and fasteners.
The jack at the right side of the beam doesn't count as a bearing surface.

I am not an expert on this and would use an engineer or an architect. It shouldn't cost as much as you might think. All you need is the beam size, how to support it, and how to attach the joists.
To an architect that's quick work.

The problem looks like you either need a bearing wall (with a proper foundation) at the right end of the LVL (center or room), or you need to figure out how to span the entire width. Spanning the entire width will require a proper foundation at both ends and would be my best guess at what an engineer would say.

A lot of typing for me, but hopefully a piece of cake for an architect.
 
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Old 07-20-16, 05:00 AM
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Another way I could go about it is to add 9 1/2 LVL on both sides of the existing beam. Sandwich it with 1/2" threaded rod.

I'd have to widen up the noth in the wall to accept the additional 2 boards, the other end should be OK as I will have a jack post under it. Would need to shim so that existing 7 1/2 beam is level with the 9 1/2 LVL, but it should be easy enough to do and will be hidden out of view anyway.

whatcha say ? I reckon the 2 of 9 1/2 LVL will be of same strength as 4 of 2x12 lumber, as in stiff enough !
 
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