Levelling floor from above

[unccivil]

I'm looking for some input from the pros...

Background: Older house (built in '72)...previous owner tiled the kitchen floor (tile+1/2"cement backer+leveller) without checking the support it could provide. The joists are 2x8, 16"OC, and run a 13.5' span. I have a 2"+ sag at the middle. I started running a series of beams (2x6's on screw jacks), but the crawl space (approx. 26" total headroom) is just too hard to work in and I now have a revamped A/C system where the duct work makes it almost impossible to work.

So, since we hate the tile they put down and we were planning on renovating the kitchen anyway...I've decided to gut the entire thing. Now my plan is to:

rip up the tile and subfloor

sister the joists level from the top (2x8s on each side of the sagging joists),

add support columns (if needed) for the outer and center beams to handle the added joist weight (200lbs or so to each 8' beam span)

replace the subfloor (having to cut the 4x8 panels to fit the new joists)and

hire out the tile work (i am not a DIY tiler)

Has anyone ever done this or seen it done? Are there any comments or potential problems that I'm overlooking? I don't have a lot of electrical or water lines, etc. that keep me from sistering the joists.

I'm good with the planning, calcs, numbers, etc.....but when it comes to bringing it together "real-world", I always find out I've missed something.

Thanks for the help!

[madronatile]

Sounds Ok. If I was the tile guy that you were thinking about hiring I'd love to be called in at this phase. Better to find out what he/she wants now than after you spend a few days framing.

[cx]

Welcome, unccivil. Please put a first name in a permanent signature line for us to use.

Sounds like you could add deeper sisters on only one side and save a good bit of work and some dinero.

But now that the subflooring will be removed, you might reconsider your mid-span bracing. Far more bang for the buck there if you can get the old joists to flatten out.

Originally Posted by unccivil

add support columns (if needed) for the outer and center beams to handle the added joist weight (200lbs or so to each 8' beam span)

Can't comment on that at all without more information.

Originally Posted by unccivil

Has anyone ever done this or seen it done?

Seen what? Sistering joists? If you'll look about the site just a tiny bit you'll see that we recommend it several times a day, on average. Very common way to bring insufficient joist structures up to par.

My opinion; worth price charged.

[unccivil]

Thanks for the input...calling in the tile guy beforehand is probably a good idea.

cx...maybe i will rethink the midspan beam. My main concerns are 1) limiting the already limited crawlspace access after the beam is in place 2) dodging new duct work and a couple of sets of water lines running parallel to the joists & 3) more of a "red flag" to a home inspector when it's time to sell

To me, sistering might be seen more as simple floor reinforcement for added tile weight whereas homemade girders and screw jacks might be seen more as a repair for a sagging floor....but maybe that's just me.

Seen what? Sistering joists? If you'll look about the site just a tiny bit you'll see that we recommend it several times a day, on average. Very common way to bring insufficient joist structures up to par.

I was wondering specifically about sistering to level from the top instead of jacking below and sistering as reinforcement

[bbcamp]

We recommend removing the subfloor and sistering to flatten floors all the time.

Sistering or adding a beam to stiffen a floor is not necessarily a red flag. But even if it was, there wouldn't be a wit of difference because each is a proven method for correcting a structural problem. Do the work correctly and in a workmanlike manner, and your inspector will see a house that has been cared for, not neglected.