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House on Crawl Space - Sagging Center Beam - Need Advise

13553 Views 9 Replies 10 Participants Last post by  Retired Builder
Hello All!

This is my first post - i've been lurking around for month and I just had to join to pitch in and also pick brains.

We live in Ontario, Canada - me and my future wife :huh: just bought an older house by the lake here in Ontario.

The house was built in three sections and started off as a cottage. I'll try my best to explain everything - forgive my lack of knowledge - i'm handy but i am still learning!

The first section was built in 1968 - then in the mid eighties a step down living room was built - then also, around the mid eighties - an apartment was added over the garage and the majority of the origional house.

The house is three bedrooms and 2 bathrooms in the main house and three bedrooms and 1 bathroom in the apratment over the house.

The house sits on a crawlspace area with access from the suken living room.

The crawlspace under the living room was built well and is about 3 -4 feet off the ground and is sitting on cinderblocks - it all seems OK under that section of the house - the floors are straight and seems to have been built well.

The MAIN house (two stories) is interesting...

The crawlspace is all sand and is maybe 6-10" off of the ground. There is NO access from crawlsapce to that section of the house - the ground is just way to close to the joists.

Needless to say - no service has been done down there since it was built - there is no way anyone could have fit down there.

The main section is about 35 feet long from end to end - maybe more - i will update with the exact measurements later on when i get to the house.

There is one center support beam that runs the entire length of the house - directly down the middle - there are joists every 16" that run over the main beam.

The main beam consists of three 2x10's all bolted together
The crawlspace is heated so the wood is dry - there is no sign of rott or water damage to any of the wood that i can see.

The main beam is supported on one end of the house with cinder blocks and bricks and at the rear of the house with a brick on top of a scrap piece of 2x10...

Needless to say - the beam is sagging in the ceter of the house and has caused the floors to sag - according to a laser level - we're looking at about 3" of sag - give or take.

2 X 10's need to be supported every 15' - but with the age of the house and the stress on the wood - i'd like to place supports every 8 feet.

I have an advantage - I have to rip all of flooring out in every room except for the kitchen - reason being.....they layed hardwood directly on the joists - no subflooring - nothing.

I will have the entire center main beam exposed from from to back to front with removing the flooring. I was thinking about digging 24x24x24 footings and pouring concrete as a jack pad - i'll have to dig quite a bit down under the beam since it is so close to the ground. From there i was going to use 20t bottle jacks and jack over 1 week until I have it close to where i want it and then supporting with cinderblocks and bricks/shims and then removing the bottle jacks. Maybe even adding additional 2x10 supports around the sections where the main beam 2x10s were joined.

Does anyone have any tips or suggestions? can it even be done? The sag is mostly in the center of the house where the kitchen is - the mainfloor kitchen is exactly where the upstairs kitchen is - there is plenty of weight in that area.

We were going to jack the beam up straight - then place a good thick vapor barier on over the dirt/sand in the crawlspace - then install subflooring and our flooring.

Any tips / suggestions / advise?

I was thinking of using the thickest plastic sheeting i can find at homedepot for the vapor barrier and 3/4" tongue and groove plywood.

Any advise is good advise!
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Ayuh,.... Ya don't need 2x2x2 Jack pads,...

12t jacks, 'n a piece of blockin' will do the jackin',...

For the supports yer gonna put under it, 'n leave, oughta be on some sorta base, though 2x2x2 might be abit bigger than ya need...

In my mind, any sisterin' ya do to the beam is just Fine, do it after it's jacked straight though...
Jacked straight, 'n supported every 8', it probably won't need it...

Oh,... in my experience, it probably won't take a week,... It comes quicker than ya think...
Worst case scenario, ya might have some drywall needin' fixin' after...
I wouldn't try to jack the beam straight. It will take time and possibly damage other parts of the structure (joist connections should be interesting to see). Instead, 24x24x12 (crawl space is dry? and should be insulated) footing every 8 feet and install new beams of 4x10 (can be jointed over the footings) for both sides of the sagged beam, then reattach the joists. More material, but I think it will be quicker.
If you decide to jack the beam into position, you cannot use hydraulic bottle jacks, as even the best hydraulic jack cannot retain pressure for very long, too much leakage of hydraulic fluid. You can use screw jacks, make sure they are rated for the load.

Jacking a beam back to level is harder than it sounds, at least if you want to avoid damaging the house. Best advice is to proceed slowly, and measure carefully using a laser level. One quarter inch at a time is reasonable, let it come up for a few hours at least, then advance to the next position. One of the nice things about screw jacks is they typically are so many turns per inch, so it is easy to advance 1/4 inch by knowing how many turns are needed.

You will need a footing to support the concrete block, if that is how you plan to support your beam. You can also pour a concrete footing close to the bottom of the beam, and install a steel plate of appropriate thickness to make up the difference.
You must be down near the beaches area I have seen all kinds of problems like this…use screw jacks as Daniel suggests, dig for a concrete pad at least 3’-0’’ deep and to be on the safe side call a local structural engineer for his input as there might be other issues besides cracking drywall etc. We have fixed problems like this before with drawings supplied showing us the materials and connections needed.
Everything everyone says makes sense, but dimensions are needed to calculate loads.

Add the following:

Get that piece of 2x10 out from under that end support.

I think that a footing 2 x 2 x 1 foot thick is plenty. I would use 16 x 16 inch chimney blocks stacked, and filled with concrete with steel plate on top for my supports. Throw some rebar in the footers. You should put plastic under the poured slab to keep moisture from coming up. You may want to consider making that space an insulated plenum with EXPS Insulation, then you can cut registers in wherever you want. Just a thought.
Spread the load as you jack up the floor by using more than one jack. Screw jack is finely adjustable. You can also make a temporary guide with some 2x's. This way, you will be able to keep an eye on the lift during the raising of your floor.
Passing through, thought I'd a word or two. Everything so far sounds good to me. I use a steel plate at the top of the jack to spread the load, keep from just pushing the top end of the jack into the wood. Just scraps of 3/16 or 1/4" steel, a couple of inches across. I almost always use bottle jacks. Yes, they won't hold the load but it's easy to just stack wood scraps under the beam, adding to the pile as you gain height. Especially in this case since you're (unfortunately) so near the ground. Alternate direction of the dimensional lumber scraps.

But if, as you jack, you find you're starting totear up the walls, just do what was suggested earlier. Sister 2 new 2x10s or some such along the existing beam and put down new joists. It'll be a lot less work (and cost) than dealing with crapped up walls. Depending on how the joists are supported at the house perimeter, you may need to lagbolt ledger boards to the existing sill plate or whatever to support the new joists. Or maybe they can just be fastened thoroughly to the ends of the current joists. Or maybe they'll just rest on the sill plate. Houses differ.

Good luck!
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I agree with the screw jacks. I just maxed out a 9 ton bottle trying to lift 22' beam with a wall on it. You have more weight than that!!
Your problem has probably been caused by unstable soil (you mentioned sand under existing supports). All the previous advise from these kind people can be applied especially screw jacks as apposed to hydraulic, but the problem is that the deep soil is settling. You need to excavate a test pit to see how deep your footings need to be so they can be placed on firm native soil. Otherwise your wasting your time and money.
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