How quick can I jack up a floor structure?

Posted by HerHusband on June 20, 2007, 10:46 am

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
joists too.

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?

Thanks,

Anthony

Posted by RicodJour on June 20, 2007, 11:19 am

> 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
> joists too.
> 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.

R

Posted by HerHusband on June 20, 2007, 1:44 pm

> A big box store or automotive store will have bottle jacks. They're
> cheap, easy to store and easy to use.

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.

> 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.

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.

> Watch for doors and windows binding.

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.

Anthony

Posted by Kickstart on June 20, 2007, 6:40 pm

>> A big box store or automotive store will have bottle jacks. They're
>> cheap, easy to store and easy to use.

> 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.

>> 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.

> 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.

>> Watch for doors and windows binding.

> 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.
> Anthony

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
support it.

good luck
kickstart

Posted by HerHusband on June 20, 2007, 7:55 pm

> Rent one!! You only need it once.
> A 20 ton jack should be about $10 a day

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.

> your wood may be u shaped from the sag

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.

Thanks!

Anthony

Page 1 of 3 1 2 3 > last >>

Similar Threads	Posted
Home Frame - Floor Structure, Ceiling Structure - Joists	October 3, 2007, 9:48 am
Home Frame - Floor Structure, Ceiling Structure - Joists	October 22, 2007, 11:50 am
Method to jack up barn ceiling.	September 12, 2006, 8:57 pm
screw jack support posts	April 12, 2007, 8:35 pm
building's structure	December 1, 2006, 3:14 am
Steel Structure	April 1, 2008, 11:25 pm
Concrete Structure and Smiling habits...??	October 25, 2006, 10:31 am
Underpnning Existing Foundation and Structure	August 23, 2008, 3:24 pm
Quick sand	July 22, 2007, 8:24 pm
Blisters in New Rubber Roof - Need quick answer	October 11, 2006, 8:44 am