jacking floor joists in multi-level - Contractor Talk - Professional Construction and Remodeling Forum

72chevy4x4 · 07-11-2009, 07:27 AM

I'm putting together a bid for a three story apartment complex (wood constuction) that needs the 2nd floor ceiling jacked up in the living room b/c of severe sag. The engineer has written up the fix-everything to his specs.

two options-first is an exposed beam supporting the joists which is easy enough. the second is burying the beam in the ceiling which involves cutting every joist and hanging them off the parallam w/ simpson's.

does anyone have experience with burying a beam like this? for an exposed beam, I envisioned the jacking the beam up which raises the floor joists. for a flush beam it seems like I would be using two exposed beams (one supporting either side of the cut) to support/raise to the new flush beam.

sorry for the length-would be nice to cover all bases in the bid.

TimelessQuality · 07-11-2009, 07:47 AM

Temp Walls....

Burried electrical/plumbing could be a deal breaker for flush.

**genecarp** · 07-11-2009, 08:01 AM

Depending on the lenth of the joists, there may be an advantage to a flush header. Often when a sag like you describe occurs, the beams will not go back, they will retain there sag, then when you try to jack, you will lift them off there plates. If you go the cut, flush header route, the low point in the sag is the cut location, giving you a better shot at acheiving a straight plain. G

For flush beam/temp wall either side of cut

SLSTech · 07-11-2009, 08:07 AM

You are also planning on putting a temp wall up in the first floor apartment also, right?

neolitic · 07-11-2009, 08:10 AM

I would add, it would be good
to build an A-frame temp wall
on the first floor as well.
Then you'll know you're raising
the ceiling, not lowering
the floor.

If you use A-frames for the two
temps next to your beam,
you can just adjust them to get
your joist back flush with the new beam.

mics_54 · 07-11-2009, 09:19 AM

duh!

willworkforbeer · 07-11-2009, 10:19 AM

Have done a couple buried beams to get rid of weight bearing walls, I used steel I-beam with 2x12 sandwich, temp walls on either side, dont forget about possible heat/air duct, tougher to deal with than elect/plumbing issues.

woodchuck2 · 07-11-2009, 10:38 AM

I dont have very much experience with this type of thing but why did the ceiling sag to begin with, poor engineering? I would more inclined to think that this building was remodeled at one time and a load bearing wall may have been removed so who knows what kind of a mess you will find when you remove the drywall/plaster. Definitly factor in stress time, headache time and of course Miller time.
I have been dealing with a similar situation that my own father had worked on in our own home. The home is made with concrete walls and first floor is concrete. Under this floor about 10-12" down is a concrete floor from a building that stood there before this one. Over time one wall in the back of the building broke through the floor and has settled a good 3 1/2"-4", in the process the floor sagged with it. My father jacked up the main beam for the floor to level the floor out but in the process this payed havoc with the wall and upstairs cielings. It has now sat so long like this that i cannot manipulate the beam, the walls or the ceilings back to where they were so i can try to raise the wall back in place. This too is a two story building with a full attic and was built in 1902, all wood is rough cut to boot.

72chevy4x4 · 07-11-2009, 01:29 PM

interesting point Gene-thanks.

Neo-what's are you referring to as an A frame? I will have to set posts down to the footer first an ensure jacking is pushing down the post, but I'm still thinking of how to do this (with ease). I have a concern of pushing up the joists and the ends (which have pulled down b/c of the curvature of the beam) not 'floating' back up the top plates but pushing against them.

severe dip is attributed to moisture damage at the 8' patio door, termite damage in spots and overloading of above floor system (gypcrete too thick).

1st floor gets 4x4 straight to the concrete floor and I will have to ensure there is a 4" slab then attach a simpson connector. squash blocks between floors and no electrical in ceilings

neolitic · 07-11-2009, 02:06 PM

Quote:

Originally Posted by 72chevy4x4

...........
Neo-what's are you referring to as an A frame? I will have to set posts down to the footer first an ensure jacking is pushing down the post, but I'm still thinking of how to do this (with ease). I have a concern of pushing up the joists and the ends (which have pulled down b/c of the curvature of the beam) not 'floating' back up the top plates but pushing against them. ..............

Instead of cutting studs to length,
cut them long and make a few
/\ , then you can just tap the bottoms
toward each other to snug, or raise
the top plates.

jtpro · 07-14-2009, 08:41 AM

Quote:

Originally Posted by genecarp

For flush beam/temp wall either side of cut

I'm curious Gene if it would be fesable if in place of building 2 temp walls that he uses adjustable jackstands instead?(depending on rental costs etc) then instead of tearing down the "walls" after, he can just pop them out. Years ago my parents had that prob and if I remember corectly(of course I'm trying to remember through my "chemical"/alchohol hase of the 80's

) the contractors used them in our finished basement to adress the sag problem of the floor joists for the ground floor. I've also seen simular jackstands used to support the plywood forms for slab pours on commercial sites.

On several occcasions for one company I worked for we had to crawl under off grade laundrymats in apartment complexes. We took a pair of 12 ton bottle jacks jacked the sag out and then sisterd a 2"X12" the length of pylon to pylon to each floor joist. So since it was a different senario we couldn't get much under the confined area and I'm curious about the jackstand application.

I await your knowledgeable reply kind sir.

**genecarp** · 07-14-2009, 01:08 PM

Quote:

Originally Posted by jtpro

I'm curious Gene if it would be fesable if in place of building 2 temp walls that he uses adjustable jackstands instead?(depending on rental costs etc) then instead of tearing down the "walls" after, he can just pop them out. Years ago my parents had that prob and if I remember corectly(of course I'm trying to remember through my "chemical"/alchohol hase of the 80's

) the contractors used them in our finished basement to adress the sag problem of the floor joists for the ground floor. I've also seen simular jackstands used to support the plywood forms for slab pours on commercial sites.

On several occcasions for one company I worked for we had to crawl under off grade laundrymats in apartment complexes. We took a pair of 12 ton bottle jacks jacked the sag out and then sisterd a 2"X12" the length of pylon to pylon to each floor joist. So since it was a different senario we couldn't get much under the confined area and I'm curious about the jackstand application.

I await your knowledgeable reply kind sir.

Adjustable jack stands are an option, the only reason i usually go with the temp wall is to avoid building a header. With the jack at each end, depending on the load, you need a header in between to support, some conditions will create a large load which would require a large header. Additionally going with the jacks create point loads. Temp wall and plates distributes the load over a larger area, This is a good thing, G

**genecarp** · 07-14-2009, 01:15 PM

One more note, jacks are used for lifting a load, as in correcting structural issues, when we refer to temp walls, they are typically not used to lift, they are used to hold, or temporarily support a load while structural changes are made. G

**ChrWright** · 07-14-2009, 01:43 PM

How much sag are you trying to get out and over what span? How long and what size is the new beam?

Was the original framing overspanned or was a structural element removed at some point? What caused the sag?

How it's done is usually a matter of the logistics in getting the beam in there. If you're tucking under--I usually prefer to slightly over jack the sag out to get the beam in place and then let the loads back down on it. Making it flush requires a lot of forethought since your temp walls will be in the way once they're up. As Gene said--if you don't have good load transfer to the foundation for your jacks--a temp wall is definitely the best way to go.

It also depends on what's on the floor above. If there are baths with tile floors (mortar beds?)--jacking could be asking for a lot of trouble.

willworkforbeer · 07-14-2009, 02:12 PM

A steel I-beam I like to use
Weight per ft depth width flange thickness web thickness
14lbs -------11 7/8 --4" ---------1/4 ----------3/16

Will hold a lot of weight for its relative lightness, cheap too compared to a lam

TimelessQuality · 07-14-2009, 02:54 PM

Quote:

Originally Posted by willworkforbeer

A steel I-beam I like to use
Weight per ft depth width flange thickness web thickness
14lbs -------11 7/8 --4" ---------1/4 ----------3/16

Will hold a lot of weight for its relative lightness, cheap too compared to a lam

Dude..........

I think we're obligated (I know I am) to refrain from making specific recommendations, that ANYONE who reads may construe as fact.

What's a 'lot' of weight ?? 'Shed roof' or Hyatt Skywalk?

Without inspecting a situation, no one can recommend anything..

From his description of the damage (water and termite), I think he has bigger problems, but I Don't Know

D@mn I'm grumpy lately

willworkforbeer · 07-14-2009, 06:43 PM

Quote:

Originally Posted by TimelessQuality

Dude..........

I think we're obligated (I know I am) to refrain from making specific recommendations, that ANYONE who reads may construe as fact.

What's a 'lot' of weight ?? 'Shed roof' or Hyatt Skywalk?

Without inspecting a situation, no one can recommend anything..

From his description of the damage (water and termite), I think he has bigger problems, but I Don't Know

D@mn I'm grumpy lately

Depends on how its loaded of course, but it is a strong beam. Anyone doing something involving support is going to have to run some numbers. Its not a specific recommendation, just an idea, throwing it out there. Is that better grumpy?

Home Work Pro · 07-14-2009, 10:24 PM

If your beam is going under, you could cut the joist above the new beam location to allow it to lift without lifting the ends. Obviously this would be done aftrer the temp walls are in.

If your going to try to make a blind header, I doubt you will be able to get enough beam strength with only a 2x10 header(assuming 2x10 joist).

I would have an engineer calculate your loads and spec out a flitch plate or beam size.

Oh and don't forget to put your header materials between the temp walls first.

neolitic · 07-14-2009, 10:37 PM

Quote:

Originally Posted by Home Work Pro

........
Oh and don't forget to put your header materials between the temp walls first.

Someone told you about that, right?

mccarty.74 · 07-14-2009, 10:45 PM

How many of us have learned that the hard way than been told it? Don't be ashamed to admit it. Neolitic I'm looking in your direction.