replacing termite eaten center beam?

[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.