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Old 11-09-2011, 07:53 AM  
johnbaum
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Default Basement Main Beam Replacement

Hello, I am a new member here but am a long time reviewer of the advice given here and it has helped me out several times. I have what may or may not be a unique situation that I need help with. I just recently purchased a home in West Virginia that was built sometime in the 30's. This home has a basement that was dug inside the homes border foundation. There is a concrete foundation poured about 2 feet beyond the basement walls and the basement walls were not mortered to the top, only to the ground level. There is a sistered 2x10 (Actually measures 2x10 as do all the floor Joists) center beam that is supported by 3 jack posts. The three jack posts are the only center support in the basement.

This area still has no building codes or building inspections. That being said, the work that went into the house, especially the center beam and the joists are not what would be considered acceptable by todays standards. The Center beam that holds the weight of the home was peiced together and fortunately was staggered however in 2 locations the floor joists are hung at one of the intersections of staggared joints. Many of the floorjoists have plywood spacer plates between the joist and the center beam and toenailed in and some were simply toenailed with an inch gap between the joist and center beam. The house is sagging in the middle with doors that won't close and sheetrock that has cracked and pushed out above most of the doors and windows. The Center beam as well as some of the joists have been attacked by termites (Appears to be an old infestation and no live termites found.

I need to know the best way to replace the center beam and rotted floor joists. The support jacks are actually receeding into the centerbeam by as much as an inch on some of them, others seem to be supporting fine.

Is this a job for a pro or can someone with carpentry knowledge make these repairs? What type of center beam would be recommended to make the repair. How would the center beam be removed? I believe that more jacks would be required to support on each side of the center beam with a 4x4 and 2x4's attached to each joist to prevent them from twisting while the center beam is out, Right? I am thinking that to get the center beam out, I would use a sawz all to cut the nails connecting them to the joists and pull it down away from any flooring nails from above. I'm sorry I have no measurements of the length of the beam but it is a small 1000sf or smaller home.

Any advise would be appreciated.



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Old 11-09-2011, 08:22 AM  
joecaption
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Time to call in some pro's on this one.
There's going to have to be some temp walls built to support the floors above while this work is being done. I'd not remove the old floor joist, there nailed into the subflooring from above and it will distroy the flooring above it if you try and remove them. New ones get sistered in from below once the beam is replaced and attached with joist hangers.
There going to have to slightly lift the house just enough to get the old main beam out with hydrolic jacks. No not car jacks just jack leged in place.
The old floor joist will get cut back enough to allow someone to have room to slide out the old beam. I'd replace it with 3, LVL's not reguler lumber.
And no a 4 X 4 is never used to horz. lift anything, it's not strong enough.
Any old house will have termites and powder post bettles and should have been treated long ago, not just looked at to see if you see them. They live inside the wood and underground and most often are never seen untill it's to late.



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Old 11-10-2011, 04:17 AM  
johnbaum
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Thanks Joe,

I appreciate the insight. I assume that there will be three LVL's needed to fill the space left from the removal of the original beam and the shoddy workmanship of the original builders or for strength? Are the LVL's strong enough to support the floor without the jack posts currently supporting? Can LVL's be ordered in a tru 2x10 to match the original lumber? I have been checking around here and the local saw mills still make the lumber as was made back then in true 2x10 or 2x4 ect... Wouldn't the LVL need to be the same size as the original floor joist so the the hangers will work properly?

Thanks again for the help.
John

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Old 11-10-2011, 07:10 AM  
joecaption
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Georgia-Pacific GP Lam Laminated Veneer Lumber (LVL)
An LVL is 50 times stonger then milled lumber and can run longer spans with less support from below, but your going to have to do some research to figure that out.
You would use the hangers made for LVL's (there wider) to reattach the old floor joist, and reguler ones to attach any sistered joist if there's room for them, sometimes I've used HD L brackets with the larger holes for lag screws when a hanger will not work.
The new beam will never come out the exact width as the old beam and LVL's only come in two widths. I suggest using the 1-3/4 ones, for one thing there lighter, and it's simpler to lift into place with the small gap you have to work with between the old floor joist.
Before any post are sat in place check for any floor sag, now's the perfect time to use the beam once the floor joist are reattached to lift the floors up before putting the coloums in.
Use lolly coloums or soild steel post with 1/2" steel plates welded to the ends with holes drilled in the plates in 4 places for nails or screws.
Anyplace there's going to be a post there has to be a footing. 24" X 24" X 24" deep. You can not just have them sitting on a 4" thick slab!
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Old 11-10-2011, 11:00 AM  
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Great advise, Thanks again for your help!

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Old 11-10-2011, 03:49 PM  
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Quote:
Originally Posted by joecaption View Post
. . . . Anyplace there's going to be a post there has to be a footing. 24" X 24" X 24" deep. You can not just have them sitting on a 4" thick slab!
Actually, joecaption's suggested footing depth would make it strong enough to support a typical highway bridge pier column. However, most residences don't have 80,000 lb. 18-wheelers driving through them. It would be a rare occasion to have the need for a 2'-thick residential footing, unless you're planning to use very substandard (3-sack?), unreinforced concrete.

Although the IRC (International Residential Code) allows footings as thin as 6" thick, typical residential footings usually range from 8" to 12" thick, depending on applied loads. Soil bearing strength and applied loads are used to determine a footing's required size (area).
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Old 11-10-2011, 04:46 PM  
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Drill a hole thru the floor 14" from the center of a post, if you don,t break thru at 6" you have a 30" footing if you do break thru poke a 1/4" steel rod down the hole and see if the footing is lower. If not drill again at 11" and 8" untill you find it.
Evan a great big footing can settle and there is nothing worse than digging up the floor to find a 36" footing and all you needed was taller posts. Bin there done that.
You asked about doing away with posts with a longer beam, by time you get to twenty feet you beam is often 18 to 20" high and a lot more money and footing are that much bigger.
We never see footings more than 10 or 12" deep with 3 or 4 rebar each way.

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Old 11-11-2011, 07:18 AM  
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Thanks for all the advise guys, I really appreciate it.

Up here in WV we have some pretty hard packed Clay and Rock. The posts that currently hold the house up are sitting directly on the basement floor. They don't appear to be receeding into the floor, the floor is not cracking and from knowing the previous owners, these posts have been in place for at least over 15 years. The only problem is that the posts are digging into the rotted beam. I was hoping that the span of the basement could be crossed without the use of posts at all to give more useable floor space (wanted to make it a "Man Cave"). If need be though, Posts could be installed and I could cut away the basement floor to pour a footer for them.

The inside of the basement walls measure 22'8" (Again inside measurements) the actual border foundation is approximately 2' outside the basement walls. The basement walls however seem very strong and show no signs of buckeling or water infiltration but are not complete (with courses of block all the way to the floor joist) but blocks could be mortered in place to make it a supporting wall with ease. I guess my question is could an LVL be used to span the 23' basement without any center supports at all? or perhaps say one at 6' coming from the wall in each direction leaving an aproximate 11' gap with no support?

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Old 11-11-2011, 11:13 AM  
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It would take an on site engineer to be able to say 100%.
Put there should never be an open area with no support, that section of the house will sag and also but more stress on the beams you do put in there.

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Old 11-11-2011, 02:18 PM  
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You can be sure the the posts are on footing, they may have put them in low and put the floor over top. Two post with 11 ft in between sounds good but you will need to install footing for the new location. You do need an engineer to look it over and I would still be drilling holes to see footing size and there is a chance the footing was put in right across the house for wall.



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