We're planning to gut and rebuild my in-laws bathroom this summer, which
will include rebuilding the old back porch so we can expand into the space
(the basement actually extends 8 feet out past the back wall of the house).
Unfortunately, water damage had rotted away the two main support beams at
some point, and my father-in-law cobbled together temporary supports out of
whatever boards he had on hand. So, I need to jack the house up on that end
and replace those beams properly before I can replace the rotted floor
Because of the missing support, the back wall of the house has dropped a
little over an inch. The rest of the floor is surprisingly level,
considering the house is 100 years old. It's only the last two joist bays
that have sagged.
So, I need to jack the floor back to level and install new beams. But, I
thought I heard somewhere you should jack a house slowly to avoid cracking
plaster and whatnot (though it's already filled with cracks and crumbling
off the walls).
Can someone tell me how slowly I should raise the floor that 1+ inch?
Also, I'll need to purchase a jack for this project. What capacity would
generally be needed to lift a one-story house?
A big box store or automotive store will have bottle jacks. They're
cheap, easy to store and easy to sue.
Generally 1/16" to 1/8" per day is regarded as slow enough. If the
walls are already cracked and crumbling, you really can't mess it up
too much anyway. Watch for doors and windows binding.
That's what I was planning to use, but I wasn't sure what size I would
need. Because of the way the house is framed, the only thing I would be
lifting is a wall, the floor itself, and the appliances and other stuff in
the house. The roof actually rests on a beam out on the porch. Weird
design, no big surprise it has so much water damage.
Thanks for the info! I'm not overly concerned about cracking the plaster,
as it's in really bad shape already and we're planning to remodel the
kitchen too at some point. Other than the plaster, is there any reason not
to jack it up quickly (all in one day)?
My father-in-law was on some kind of leveling kick about 20 years ago and
had jacked the house up more than 6" above the foundation at one point. I
don't know what he thought he was doing... :) But, I can't do much more
damage than he did.
As you might expect, the doors don't close properly now, since the floor
has sagged over an inch in places. So, I can't make it much worse.
We're planning to install a new exterior door anyway as part of the
remodel, but there's one large window that concerns me. It's a single fixed
pane, about 3' high and 6' long. As far as I can tell, it's just a piece of
glass sitting on the framing held in place by wood trim strips. Not exactly
energy efficient, as it rattles around anytime the back door is opened or
closed. But, that window is in the wall I need to raise, and I don't want
to get the glass in a bind and break it. Although, in theory, if I lift the
doubled joists under the wall, the entire wall should go up as a unit.
Rent one!! You only need it once. A 20 ton jack should be about $10 a day,
and if the seal blows out return it and get another one.
You can jack up the sag pretty much all in one day.
The problem is your wood may be u shaped from the sag and you will just be
making the center and both sides higher as you jack.
Chances are you will have to install new floor joists along side the
existing sagging one and jack the new straight one, when the sag is gone to
a degree you are satisfied with nail the new one to the sagging one and
I'm going to look into it, but my in-laws live in another town which means
I'm usually only able to work there one or two days a week. Considering the
low cost of the jacks and the hassles of rushing around to get the rental
back, I'll probably just buy one. I'm sure I'll use it again for something,
or I can sell it when I'm finished.
I'm not concerned with joist sagging, it's a 100 year old house afterall.
But, I need to replace a couple of beams that have rotted away and the wall
and floor above have settled down over an inch. To be honest, I'm not sure
what's keeping the floor from collapsing completely. The beam rotted away
many years ago, so my father-in-law just cut it off and cobbled together
some temporary boards in it's place (a few 2x4's instead of the original
6x8 beams). Scary! :)
I need to jack things back up so I can put some new beams in.
I jacked up a 10ft by 15ft bedroom "shed roof" addition over 7 days
(obviously lighter than the house proper) that had nearly a 4 inch
drop......using a single 5 ton and (2) 3 ton jacks over the 15 ft width with
a beam supported by the jacks.......had no trouble with the load but today
would probably use a couple of 10 or 20 ton jacks( if for any other reason
they are so much cheaper today)......It creaks a lot and since nails,
fasteners etc. need to move.... gradual is a very good idea.....although if
your doing only a inch I'd think a day or two would be okay (Keep in mind
I'm no expert and longer is always safer as not all parts will necessarily
move at the same rate)......Jacking can also stress the glass depending on
where the windows are, I once lost a 5ft by 6ft window to a bad sinking
corner post, about the time you notice the window is stressed it is too
Hello, I have done about 25 of these kind of things in Port Townsend,Wa.
Yes I have cracked some walls but I have never broke a window. I lift
and support whole sides at a time and I say jack it up slowly taking
about all of 15 minutes. Its a small job on a small house. Use two jacks
sitting on a good pad and a 6x6 beam against the joists. Go slowly doing
3-5 pumps on each jack going back and forth between them. Don't worry
and stay clear of the jacks and never go under the load or leave the
load on a hydraulic jack. In fact you might see if you can rent screw
jacks. You may look my number up and call me if you want more info. TonyG
The entire wall is only 24' long. There were originally two 6x6 beams at
8' OC. Because the porch was exposed to weather (and sloped towards the
house), water leaked in and rotted away the ends of the two beams (the
basement extends out under the porch). So it's only the center section of
the wall that has sagged down where the beams used to be.
My "plan" was to put up some beams just to the side of where the
originals were and jack up the floor a little on each side till it's
level enough that I can cut out the remaining section of the beam and
slide in new replacements.
As long as I can get it done in a day or two, that'll be fine with me.
I'm not in a huge rush.
As for cracking the plaster, that's not really a concern. We're gutting
the bathroom anyway, and building a new wall between the kitchen and
bath. The only remaining wall that may be affected in the kitchen is in
really bad shape already, so I can't make it much worse. :)
I only need to raise the outer two joist bays (about a four foot
section). I was thinking of using a temporary 4x6 or 4x8 beam (every 8'),
with a post holding up one end, and the jack under the other to lift and
level at the same time. Then I would slip a post in to replace the jack
while I work on things. Sound workable?
One other thing, assuming I use a 4x4 post on top of the jack to do the
lifting, do I need to do anything to prevent the post from digging into
the end of the lifting post? There really shouldn't be all that much
weight, but I've never done this before so I want to be prepared before I
start the job.
I am not sure what your are asking in the paragraph ending Sound Workable?
Do not use a 4x on top of the jack. Make a pile of blocks or cribs to
get the jack directly under what ever you are lifting. Place a piece of
steel plate between the jack head and the object being lifted. I think
you should consider hiring a carpenter with experience in lifting. Tony
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