Sagging floor joists

[pinkertonpv]

I am the second owner of a 30+ year old house that I am remodeling. I have lived in the house since 1993. I am putting laminate flooring in the first floor area (kitchen, dining room and entry hallway). In preparation for the flooring, I removed some carpeting in the DR and could see some water damage and some sagging of the floors along the three interior walls. I removed the floor/subfloor in the water damaged area and noticed that the 3 walls (loadbearing and supporting the 2nd floor and roof) were not centered over the floor beams. Two walls (parallel) were about 10 inches off the beam and riding over the floor joists. The walls increasingly sagged from the exterior wall side to where they connect to the third wall. From 0 to about one inch. It appears that each succeeding floor joist increasingly sags lower than the top of the beam. Joist hangers were not used. A two inch ledger board on the bottom of the beam supports the joists. The third wall connecting the two was centered between two joists and supported by the plywood only. To complicate matters more, much of the plumbing proceeds in the area of the third wall and beam. The concrete block support columns in the crawl space supporting the beams and joists were not located properly, thus the beams could go under the support walls.

I think that maybe the foundation and floor framing was completed and the wall design changed.

I plan to use screw type floor jacks and 4x6s under the walls to raise the floor enough to level it and be able to install the laminate. I will leave the jacks in place. The crawl space is tight but i have most of the floor in the DR up and have access to the beams/walls. No pictures available but I would appreciate any advice. I am an average DIY with sheds/decks/walls/windows etc on my resume. Am I missing something?

Second problem is that one of 3 2x10s from a separate floor beam that runs under a bath room has has been cut to allow drain pipe and water service line access for lavatory above. A water leak from the drain has weakened the cut 2x and caused it to sag dropping the floor an inch or so. I had a worker jack up the floor beam in two places with screw type jacks. this helped some; however, the floor is not level enough to install the laminate from the first problem. I plan to add another screw jack and see if I can level it some more. Again screw jacks will be left in place. Any comments?

Been thinking of just getting a contractor in and have them do it also. Wife is getting on me about not getting things done quick enough.

[pushkins]

Firstly, what your attempting to do isn't to be taken lightly, if you do something wrong under load bearing walls all matter of hell can open up around you very quickly. When jacking your floors/walls/joists make sure you do it evenly and slowly to help alleviate the walls movement and drywall/plaster cracking.
Make sure you have your jacks well supported with solid concrete blocks (2x8x16") or good quality solid 2x10/12 lumber blocks to help take and spread the loads.

You could always add piers in your crawl space to take up the load bearing wall weight.
Simply raise the floor joists with your screw jacks (SLOWLY), then dig down below your frost line or 32" whatever comes first, pour in concrete and add posts to help support your 4x6's.

Are the floor joists sitting lower than the bearers ? ( have they slipped) or have the bearers and the floor joists settled ?
If the bearers are about where they need to be and the floor joists have settled below them, then a solution is as simple (easy for me to say...) as jacking the floor joists up and installing joist hangers and if needed the above mentioned extra support piers.

As for adding the screw jacks and leaving them there to take the loads forever, it's not my solution of choice as it's sort of a half fix. Again with your bathroom I'd be lifting the floor to where it needs to be or as close as you can get it and then digging in a new pier/s.

[killerformula]

I think I'm going to piggy-back on this thread as we have a similar issue at our house. Thanks in advance for any advice...

We have a 9x15' addition on the side of our house which on one end sits on a concrete block wall, and on the other, virtually nothing save a couple of concrete blocks in the corners. The floor on the unsupported end has begun to sag in the middle, predictably.

The house sits on a hill, however, and the crawl space is very narrow at the sagging end. I can't even crawl under there, its maybe 10 inches of access. So I cut down through the floor and I see my joists which look to be solid.

My plan is to dig down about 36 inches and pour a flat form of concrete. I was debating using some type of screw-jack support to go on top of the concrete form and hold up the joists.

I'm a little worried, however, that because of the slope that the hole I dig will probably need to be filled in, otherwise I'm sure it would fill up with water. Can these type of supports be placed under ground? I think a giant, 36 inch thick concrete form is probably out of the question. Another idea I had was to stack concrete, foundation-style blocks on top of the form and use those to raise the level of the jack above ground.

What do you guys think?

[pushkins]

Your are going to have to determine just how many supports you need at the area in question. Lets assume your doing one.
To start with you need to dig down past the frost line (if you have one), if you do not have a frost line issue then you need to ascertain how deep you need to go for a footing, here in NC it's 12" as we are on sand, in Mid. Ohio with frost levels and clay the footing needs to be 32" min.
Assuming you dig down 36", you will need at least a 8"-12" thick footing of concrete before you can put anything on it.
If it were me in your situation I'd be adding one jack in the middle of the length, I'd dig a hole 12"x12" 36" deep, once you out of the ground form up so that the concrete is a little higher than the surrounding area (keeps water off the footer) I'd fill the entire hole with concrete it's only 3 cubic feet and you have the floor torn up so it's not a big issue in working in just a crawl space area. On top of this once it's set (allow 7 days if you can) stand your floor jack to support the end wall bearers.

Unless you intend to mortar the concrete blocks together you cannot stand a jack on them.

You could just dig a 20" long x 12" wide x 36" deep hole and pour a 12" thick footer then lay cinder blocks (mortared together) until you come clear of the ground then the final block will need to be a 4" solid cap block then you can stand your floor jack on this.

It would be much easier to just fill the hole with concrete, this way your creating a solid pier.