What should this job cost? (jacking up a house)
#11
I live in small cape cod in Central NJ. I've noticed a lot of the floors have a dip in them as you walk towards the center of the house. A guy came out and measured-- and found that the main beam in the crawl space is actually crowned in the center, not low-- but it's the undersized floor joists-- 2x8s that dry are more like 7 1/8 to 7 1/4. Each joist runs about 11 to 12 feet from the block wall to the center beam.
Because of accessibility, the contractor has suggested 2 laminated beams to run the full width of the foundation (about 30 to 40 feet) and have them split the difference, so there would be one in the front half, one in the back half. They'd then use 6x6s with 1/4" plate steel to distribute the weight on the floor (as not knowing the full depth of the foundation)
They'd use jacks to lift up the center of the span, then put the laminated beams in, hence straightening out the dip.

What do you think this job should go for?

Colin
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#12
I'd want to see the floor cut out and proper footings poured.

I have no clue on cost. Maybe $2 to $4k?
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#13
Mr_Mike said:


I'd want to see the floor cut out and proper footings poured.

I have no clue on cost. Maybe $2 to $4k?




I'd have no clue on cost either, but cutting out the floor to the required depth and pouring new piers is going to add substantially to that.
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#14
I would call an engineer to find out if sistering steel to what is there would work to get the sag out. I have done this in the past where I jacked up the floor joist so the floor was level and then through bolted steel to what was there, the steel more than made up for the size of the floor joists. In any case I would have an engineer give it a look as the fix you describe may or may not be the way to go. Also if you deal with an engineer mention steel as some won't give it a thought unless it is brought to their attention
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#15
I'm not seeing the need for reinforced floor joists. Is the bow mid span unacceptable as it is?

Regarding the beam, I like the idea but wouldn't want 1/4" plate. Too thin and too easy to rust away. I would go much thicker and have some reinforcing bars added.

My guess is 4-5k.
Mike

Non impediti ratione cogitationis
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#16
the original thought was to bring up the main beam in the house--assuming it was sagging too...then if it didn't make a difference, they would start sistering joists with lam beams.
When he found out the main beam was crowned, not sagging, they started talking about sistering--but that would mean pulling off the rim joist from the outside to slip the beams in there--guess they didn't like that idea, so this extra beams to cut the span was what they came up with.
I think their price was a little high--but waiting to see if anyone else has a guess...

Colin
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#17
I too wouldn't do a thing without a structural engineer involved. I'd also be concerned if a contractor did this work without consulting one. I know that nobody likes to spend too much money but it's worse spending it more than once.
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#18
I think you need a second opinion. I don't like the story about the unacceptable bow on 2x8's with a 12' span. I have a house with a 15' span and 2x8's and it's been there for 70 years. My attic called for 2x8's in it with a 15' span as well (I think) and it was engineered.

I'm also not liking the story about it bowing up. I'd buy that it has heaved or moved in some way, but not that it bowed against the weight of the house after it was set. Maybe it happens, I've just never seen it. I've done the work you are proposing half a dozen times.
Mike

Non impediti ratione cogitationis
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#19
Without knowing the full details, engineering, contractor's skill and experience in these matters, etc., my SWAG would be anywhere from $5,000 to $12,000.
Any free advice given is worth double price paid.
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#20
I'll confess I don't understand what is supposedly happening. The floor dips towards the center of the house, but the main-beam running along the center is high ?

Or does "crowned" here mean that the ends of the main-beam have sagged but not the middle (or the ends have sagged *more* than the middle)?

Personally I would get under there with a string line and mason's level and figure out WTH is going on for myself.

Secondly, if something needs jacking, why not use short lally columns? They are available in just about all sizes and adjustable. And I've heard jacking needs to be done slowly to minimize the damage to finished surfaces - making lally columns with their screw jacks ideal.

Finally, I almost hesitate to ask, but do you have thick concrete floors in your crawlspace, or is the contractor recommending a steel plate on a dirt floor to carry the weight?

Because that will be relatively cheap and with commensurate long-term results, I fear (and an anonymous call to your local building code authority might confirm the fear).

http://www.oldhousejournal.com/sagging_f...azine/1466

-Mark
If I had a signature, this wouldn't be it.
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