[Alan]

Here's my original thread : http://www.diychatroom.com/f19/what-going-here-133078/


What i've done since the last time I posed in that thread : I've removed cabinets from the other wall (with my wife's blessing) that were impairing my ability to check level across the entire room.

I used a string line (very tight) and a line level to check the top plates from exterior wall to the wall in question, and it looks that the wall in question is lower than the exterior wall by about the amount that the top plates are distanced from one another in the original thread.

I did the same thing with the bottom plates with the same result.

Between the two walls, the floor system has 2 beams. The sag is not noticeable by eye until between the load bearing center wall, and the adjacent beam.

My plan is to set my string / line level on the beams below the house, and jack up the beam ~1/2" or until the line level reads "gravy"


Looking for any insight or things that I need to be careful of when i'm doing this. Thanks in advance.

 

[oh'mike]

Is the house on a crawl space?

Will lifting the beams or beam also be lifting the second floor? If so ,is the second floor also sagged the same way?

Are you prepared to dig and add new pads for additional support columns?

Automotive bottle jacks are dangerous to use--the lifting surface is so small that it will punch a hole and then split an oak block---consider renting house jacks ---and some good wood cribbing--

Get us a picture from under the house---wide angle----show the ground---the beam and the existing column---

 

[Alan]

Yeah the house is on a crawl space.

Ok, i'll work on pictures tomorrow.

By measurement of the top plate, I only need to jack it somewhere in the realm of 1/2" I'm thinking that if I jack it 1/2" I can add a layer of plywood between the beam and post. It only appears to be sagging in that one area which is where center of the span for 2nd floor exterior wall is sitting. (this is also the same set of joists where I've added some double 2x4 last weekend for support)

Perhaps a little more work with my line level under the house tomorrow will reveal some more information. I'm tempted to just hire this one out though.

If I decide that this isn't too much for me to handle myself, how large of a footing should I place under this point? Crawlspace is tight, but i've been in tighter. I can go hands and knees between the beams, so digging isn't out of the question.

 

[oh'mike]

Depends on your soil----if it's stable and doesn't freeze----I would dig down about a foot---build a form about 24x 24---one foot tall----


Daniel Holtsman or one of the other engineers might have a better number----

I think you can do that----I've had to jack houses much higher ,where a risk if shifting existed---

 

[oh'mike]

Do not use hollow cinder blocks for 'jack stands' --they can shatter---

 

[stadry]

in the past 2 yrs, we've jacked 3 condo units - 2 story - using 50t railroad jacks on 4x8's temp cribbing w/steel plates on top of the stands as a spreader,,, while they temp hold, new sufficient strength/size rebar reinforced conc footers are properly installed & fitted w/permanent steel plates attached to the joists to spread the force,,, we used conc filled adjusta-posts for the columns,,, its not difficult work & pays well - just use your head & overbuild :thumbup: the 1st was done under the supervision of our retained pe - 2nd & 3rd didn't require his stamp - only a lesser fee for the approval letter,,, would NEVER consider ply of any size for a pad/spacer

 

[hand drive]

sometimes when jacking a floor system shims can be placed on top of the current piers but chances are the piers will settle more if settling is already occurring so new upgraded piers would be needed. The pier could have settled that amount and will not settle further but no sure way to know for sure unless you jack up the floor and shim onto the pier and keep an eye out for settling over time since you live in the house. if the pier is compromised building the pier with a proper footing that will not settle is the best way to fix it though, if they built the house on top of back fill then you could be digging down there forever to find original sub soil...

 

[Alan]

Luckily for me, it only seems that I have about a 5 foot area that has settled. The floor in areas between 5-10 from this spot seem fairly level, so i'm certain that there's a problem with the support underneath that particular spot. Perhaps the pier is in the wrong spot, not carrying the load directly from the double 2x4 that I just put in. It may just end up being a matter of a couple of jacks and setting one new pier.

 

[Alan]

Okay, I think I can do this with the right jacks. It's been really wet out so i didn't want to try hauling a camera under the house.


What style of jacks should I use?

Are these any good? http://www.homedepot.com/webapp/wcs...p=BazVoice-_-RLP-_-100595081-_-x#.UL9qK4M72Ag

I know I don't have enough room underneath for a hi-lift.

The other option are 20 ton screw jacks, which i'm finding are about 100 bucks EACH for them. Obviously I want to do it safely, but if I have to spend 300 bucks on jacks, I just might need to change my shorts (and wait until after Christmas) Is it worth the extra cash for screw jacks, or will the hydraulic bottle jacks do just fine?

 

[Canarywood1]

Why not just rent the jacks you need,railroad jacks as previous poster said is what you need.

http://www.ccmrental.com/0,81,railroad-jack.html

 

[Alan]

I'm sure by the time I rent them, set them up, dig out a footing, pour concrete, install posts/brackets, the amount of money i'm spending renting them I could have bought my own anyway.

:huh:

And, I only need to raise about 1/2". I dont think a notched jack like that will give me the flexibility in increments that I need.

 

[hand drive]

I'm sure by the time I rent them, set them up, dig out a footing, pour concrete, install posts/brackets, the amount of money i'm spending renting them I could have bought my own anyway.

:huh:

And, I only need to raise about 1/2". I dont think a notched jack like that will give me the flexibility in increments that I need.

with the correct set up a large 50 or 60 ton bottle jack with a 1/2" piece of scrap metal plate a few inches square placed between the jack and the post and a good jacking base should get the floor girder jacked up. if possible I'll make the cement pad wider so as to have a wider jacking surface to get the jack and new support on the same pad, jack it up-support it, take jack down and done.

on another note, I've used jacking pads also made out of layered 2x12 and 3/4 plywood built 4 layers thick total about 24" square with a carrying handle( I've spent many hours dragging that thing under houses to jack the house up). All you need is a flat spot in the dirt for the pad, sometimes a spot needs to be dug out depending on the dirt under there.

Also, the diameter of the jack matters a lot too, the bigger diameter the better so the metal plate and post do not kick out while the jack is used. I've had a friend experience an exploding metal plate from to much jack pressure so even that is not the safest if not careful, his face was riddled with specks from the flying metal fragments, had safety glasses on so =no damage visually.

 

[Alan]

with the correct set up a large 50 or 60 ton bottle jack with a 1/2" piece of scrap metal plate a few inches square placed between the jack and the post and a good jacking base should get the floor girder jacked up. if possible I'll make the cement pad wider so as to have a wider jacking surface to get the jack and new support on the same pad, jack it up-support it, take jack down and done.

on another note, I've used jacking pads also made out of layered 2x12 and 3/4 plywood built 4 layers thick total about 24" square with a carrying handle( I've spent many hours dragging that thing under houses to jack the house up). All you need is a flat spot in the dirt for the pad, sometimes a spot needs to be dug out depending on the dirt under there.

Also, the diameter of the jack matters a lot too, the bigger diameter the better so the metal plate and post do not kick out while the jack is used. I've had a friend experience an exploding metal plate from to much jack pressure so even that is not the safest if not careful, his face was riddled with specks from the flying metal fragments, had safety glasses on so =no damage visually.

You really think I need 50 or 60 ton jacks? I did some searching for estimates on weight of a house, and it seems one my size is somewhere in the 60 ton range. It seems to me that I should be able to get away with less since i'm not jacking the whole house up. Also, can someone explain the cribbing mentioned above? What purpose does it serve?

Thanks.

 

[oh'mike]

Cribbing-you need to jack on top of something---so heavy wood is stacked up to get the jack high enough to do that---

you are only lifting 1/2 inch----as long as the original support will not be removed---go ahead and try the lighter weight jacks---

I do most house lifting using a jack wall or a jack post---to bad you have so little space---

A lot of jacking can be done with a 2x6 stud----cut to long and then beaten into place with a sledge hammer----More details if you want them---Mike----

 

[hand drive]

You really think I need 50 or 60 ton jacks? I did some searching for estimates on weight of a house, and it seems one my size is somewhere in the 60 ton range. It seems to me that I should be able to get away with less since i'm not jacking the whole house up. Also, can someone explain the cribbing mentioned above? What purpose does it serve?

Thanks.

The larger jack is more for the larger diameter it provides at the lifter shaft, or whatever you call the part that raises when you jack it. the diameter of that part on a 50 or 60 ton jack will be 2 or 3" so that helps tremendously when jacking as compared to a jack with just a 1" diameter lifter shaft when it comes to kick outs. The jacks may want to resist the upward force and send the force sideways so the flatter and wider the bearing point between jack and post the better.

A tip when using the jacks, raise a little at a time and use temp posts if possible to hold it all up if you have to readjust the jack midway into lifting. sometimes it takes a few times ( jack set up) to get the amount that is needed.

 

[Alan]

Okay. I don't think the cribbing will help me here, since I have probably less than 18" between the beam and the dirt. Would it be easier to use a premade pier block?

I might buy 2 or 3 of those 20T jacks in case I need to re-position something.

I'm assuming a steel plate between the jacking head and the beam is the best option because a piece of lumber will probably split, crack and deteriorate rather quickly, as it doesn't have the compressive strength needed for that application?

I probably won't even need a post between the beam and the jack if i can easily elevate the jack 6" off the dirt.


As for the amount of space, I dont think it will be so bad. 4x10 beams (i think) so in between the beams, i have a good 24" of crawl. That's a lot for me just as long as nothing comes down on me. (not likely considering the amount of the floor i need to move.)

 

[oh'mike]

You are only lifting a short distance--and if something fails--the house will drop back only an inch or so---

Se if you can find a short section of rail road tie or other heavy timber---I don't trust concrete blocks---they can crack to easily---but once again--the worst that could happen is the house settles back an inch or so---

 

[Alan]

Thanks Mike. I bet my dad has a chunk of railroad tie around somewhere.

:thumbup: