replacing termite eaten center beam?

[2manyrocks]

Well, the termites have eaten up the center beam of my parent's house. They used rough saw oak lumber because that was the only lumber they could find after WWII. It's a single story house. The beam consists of 3 oak boards nailed together. Each is 1.5"x9.25." The floor joists run past one side of the center beam far enough that my current plan is to build a 2x4 wall 16" OC under them. The wall will rest on a pressure treated 2x4 plate on the concrete floor with a doubled top plate.

Since the walls are plastered, I need to minimize the amount of lift used to get the weight off the existing center beam. One problem is that the beam has already sagged over an inch in the very center of the house.

In cutting the studs for the temporary support wall, how much longer should I cut them to get the weight off the existing center beam? I figure the weight of the building will compress the wood in the top plate and the plate resting on the floor, too. I'm not sure whether to cut the studs say an extra 1/4" too long to start with or whether that is going too far.

I'd like to correct the 1" sag in the center while I'm at this, but am having a little bit of apprehension about fixing a bunch of broken wall plaster later if I go too far.

 

[pmsmechanic]

I would be tempted to just use a temporary beam and teleposts and slowly lift the house back to where it should be, Then remove the termite eaten beam and replace it.

 

[cmyoung2]

Use some basement jacks for the temporary support. since they are screw adjust, you can fine tune how much you lift. If you need to leave in place, just build a wall around them.

 

[2manyrocks]

The beam is about 30' long with two support posts. The center part of the beam is 112". How big and long of a temporary support beam are we talking about? A temporary support beam would tend to spread out the load of the floor being raised into position without so much plaster damage compared to raising one floor joist at time? I assume I'd have to at least work in 10 foot sections. How many jackposts would be needed?

This is the good side of the center beam. The back is eaten up.

 

[pmsmechanic]

I already see one telepost (jackpost) in the picture right on the right side. You could probably get away with three but four over the 30 feet would make the job a lot easier. I would check a rental place to see if they have something you could rent if you don't want to buy.

A house mover might have a beam you could use temporarily.

I would be temped to do the whole thing at once instead of in sections. There would be less damage to the plaster. See if you can't get a 6x6 or an 8x8 treated post long enough to use as a beam. If you are planning on leaving the beam up there the bonus is that termites don't eat treated wood.

 

[doxford jim]

Just a thought but would a metal "I" beam be better for the work you intend doing. I doubt that it would sag under load if a deep beam is used. You can put as many or as few jacking posts in as you see fit. This would allow very controlled adjustment and be versatile is use.
As I said, just a thought. If you are going to try and fix the sagging, you need something that just won't move when put in place.

 

[BeezFun]

I had similar problem in an old house only it was powder post beatles that ate it up. I used shoring jacks and short pieces of 4x4 on each side of the damaged beam to raise floor joists slowly. Using short pieces allowed me to avoid conduit and other obstacles. I lifted them about 1/8" every few days until it felt like I was doing more damage than good. I had a steel beam made the right length, and put it under the damaged beam. I used a few telescoping columns along it's length, and dug holes in floor for concrete support piers to rest them on. I had to do a lot of shimming on top of the steel beam because the wood beam wasn't straight. My buddy is an engineer, he sized the beam for me but you could find tables online that will tell you how big to make it.
I would not try to remove the damaged beam, the floor joists will be toenailed into it and you'll just make a mess trying to tear it all apart.

 

[2manyrocks]

I figure I will have to use a sawsall with a nail cutting blade to saw out the old beam. It is so eaten up that I feel like it has to go.

My research is that a 4x8 I beam ought to carry the same load as the built up oak beam. But 30' of it will weight close to 400 lbs.

I do have some heavy scaffolding that was formerly used as concrete staging with the screw jacks. I wasn't sure if I should try to use it or not. The cross bracing would seem to make it less likely for a post to jump out.

 

[BeezFun]

I figure I will have to use a sawsall with a nail cutting blade to saw out the old beam. It is so eaten up that I feel like it has to go.

Well that will certainly give you a cleaner job.

My research is that a 4x8 I beam ought to carry the same load as the built up oak beam. But 30' of it will weight close to 400 lbs.

It looks like the existing beams are supported at about 10'. I assume you'll use those same supports for the steel beam, which means each piece is about 10', which shouldn't be too bad. A 4x8 beam 10' long seems reasonable to me. My basement has a 5x8 on 13' centers, but it really depends what that beam is supporting above.

 

[Cat_Driver]

Yep that was my thought. A nice Steel I beam
Also
here

How to change a one-ton beam on your own! - YouTube

AllianceCarpentry's channel - YouTube

 

[mikehaugen]

I figure I will have to use a sawsall with a nail cutting blade to saw out the old beam. It is so eaten up that I feel like it has to go.

My research is that a 4x8 I beam ought to carry the same load as the built up oak beam. But 30' of it will weight close to 400 lbs.

I do have some heavy scaffolding that was formerly used as concrete staging with the screw jacks. I wasn't sure if I should try to use it or not. The cross bracing would seem to make it less likely for a post to jump out.

Where are you located? If anywhere near northern IL I have got a few 8" i-beams you would be more than welcome to use for your temporary supports, I'd probably even give you one for the permanent beam. I don't remember the exact size, but if you are interested I will check.

 

[2manyrocks]

I'm in middle Tennessee, but thank you for your kind offer.

 

[jaotguy]

crib up under the old joists ... on each side ... get some cheap HF 8 to 10 ton bottle jacks and release the weight on the center span beam ....then:

possibly a new 2x 8 (10?)... one each side of the old ones... lagged thru ( sandwich style) and glued to them too.... ( doesn't have to tie in all the way completely ).... then put 2 layers of "plates" under the new beams and lag and glue to the top ( new side ) units .... stagger the plate joints .... ( think U shaped box )

then crib up under the new main beam and jack up slowly till straight ( run a tight string from one end to the other of the main beam , off to one side a bit ) when the beam is the same as the string , you are straight ....

then pour cement footings , put jack posts ( adjustable ) on the new footings and tie to the new main beam. ... adjust till snug ..... return in a couple of weeks and re tension the jack posts ... ( and bring a bottle jack just in case )

 

[2manyrocks]

Hmm, this is part of the reason I want to pull the existing beam out.

I looked at support jacks at my local home center was not favorably impressed with the thin metal pieces that go at each end of the post. The post itself looks a lot thinner than I remember these things. The only way these things can meet the load rating must be based if they are installed per the installation instructions with a thicker piece of metal. What they include in the package is not what I would use.

This may mean a trip to the salvage yard to see what I can find there.

 

[BeezFun]

Hmm, this is part of the reason I want to pull the existing beam out.

Why haven't the floor joists been affected by the termites? Did you just get lucky and catch it early?

I looked at support jacks at my local home center was not favorably impressed with the thin metal pieces that go at each end of the post.

I agree, they're crap, that's why I only used each one to support a couple of floor joists. So I probably had at least a dozen of those things on each side of the main beam. I reused the old support columns once I put in the new beam.

 

[/pine]

Hmm, this is part of the reason I want to pull the existing beam out.

I looked at support jacks at my local home center was not favorably impressed with the thin metal pieces that go at each end of the post. The post itself looks a lot thinner than I remember these things. The only way these things can meet the load rating must be based if they are installed per the installation instructions with a thicker piece of metal. What they include in the package is not what I would use.

This may mean a trip to the salvage yard to see what I can find there.

It sounds like you are describing the "Tiger" brand jack posts...sold at HD etc...?
FWIW...
I have found them quite usable...with a slight modification or two...
first I welded the screw part to the top tube... on some I welded the plate to the bottom tube...I also drilled some smaller holes in the top/bottom plates so I could just screw the bottom to a short 2x8,2x6 etc. drop...and the top to whatever...
...Screw the top plate to what you are lifting and use a plumb bob from the center of the dimple and place the bottom plate (that's screwed to the wood block) at the plumb point....

 

[2manyrocks]

The termites have been into some of the floor joists, too. One of the rim joists is also shot. It has a poured concrete floor next to it, and I only have access to one side of the rim joist. I have no clue how to deal with the rim joist.

I'm thinking I may install some wooden posts in a couple of places so I can reuse the jacks that are present. It may be that the screw jacks in them are rusted solid, however.

 

[BeezFun]

The termites have been into some of the floor joists, too. One of the rim joists is also shot. It has a poured concrete floor next to it, and I only have access to one side of the rim joist. I have no clue how to deal with the rim joist.

Wow man, I'm glad I'm not you. One thing you can do with the rim joist is repair it from the inside by blocking each joist cavity from the inside. It's tedious but cheap. It's easiest to shim one side and the bottom, rather than trying to cut them to fit. So cut each block about 1/8" small, put adhesive on the top edge, on the face that touches the rim joist, and on one edge. Push it tight against one floor joist and the underside of the subfloor, drive shims underneath and on the side, then screw it to the rim joist to hold it in place. Then drill a clearance hole through the next floor joist cavity and screw into the block right through the shim. That will help stop the floor joists from rolling, and will also provide support for the floor plate above. I assume you already had somebody send all the termites to their grave.

I'm thinking I may install some wooden posts in a couple of places so I can reuse the jacks that are present. It may be that the screw jacks in them are rusted solid, however.

Wooden posts aren't adjustable, not really very easy to use. I did the same thing /pine did- I tack welded that chincy plate on both ends of the support jack, and taped that telescoping pin in place so it can't fall out. That made them much more useable. I sold a bunch of them on craigslist when I was done. I think I had about 20 of them and kept a few for future projects.

 

[KubotainNH]

That doesn't look like fun. I bet the picture doesn't tell all the hurdles that need to be jumped. I think I would brace it up on both sides of the old beam using something like 4x4 or even 4x6's with the telescoping posts supporting it. Maybe 2 or 3 feet away from the beam so you have space to work. I beam would be good but heavy. My house has an engineered laminated beam in an area that does not have a support beam. It is layered and seems quite strong and not super heavy. I don't see the bugs liking it either.

Engineered Lumber | Galliher & Huguely
Choosing Engineered Beams For Heavy Loads And Long Spans - JLC Online Page 1 of 3

 

[2manyrocks]

The scrap yard doesn't have I beams at the moment, but they have the one sided flange beams (C beams?) that are 8" deep x 20' long and a couple of 10 foot long sections. Looks to me that I should be able to bolt them back to back to make a strong enough replacement beam 30' long. A 20' section would weight about 200 lbs. Doubled up back to back would push it to 400 lbs. So it would be easier to to deal with bolting pieces together instead of welding them together and then trying to install them. I don't like the fire hazard of welding in an old building. That's why I'm thinking of bolts. The existing wood beam is spiked and bolted in a few places anyway. End result would be termite proof. I'd have to knock a hole in the outside foundation to slide in the 20' beams.