So, I own an old bungalow built between 1910 and 1922 (found conflicting dates). It has what was a cellar or crawlspace and was dug out in the 40s or 50s. It now has bench footings and the ceiling (floor to bottom of 1st floor joists) is ~ 6ft. I'm planning on doing some work in the near future and am trying to get my plan set in my head before hand. I have a 2 part question:

1) There is a main 8 x 6 beam about 23 feet long. It is supported by 2 TREE TRUNKS as beams (you can see where branches used to be, pretty cool). The beam is fine almost level, may be sags 1/4 inch in the center. Not too bad, not to worried. The beam, how ever has cracks through the middle parallel with the beam. They don't go all the way through. Here's some pics:

100_2436.JPG - Windows Live

They are a bit worse between other joists. My question is will it help if I cut 3/4 plywood ~ 14 x 8 and attach it in between the joists on both sides of the beam with 10d nails or deck screws to help keep it from cracking further? I'm not worried about cost or time for this project. Just wondering if it will help. Also, not planning on replacing the beam in the foreseeable future unless something happens.

2) The joists for the 1st floor are 2 x 8s and span ~ 11 ft. which of course under sized, its old. There is a decent amount of flex in the floor (which is visible in the basement when people are walking heavy footed). I want to stiffen the floor up with out adding larger lumber (head clearance is already tight.)

Will sistering same sized boards to the existing joists with a piece of plywood laminated in between the 2 work? If I'm going to add new boards, what about adding new joists ~8 inch on center and not sister the joists? Any ideas?

Since I am planning on doing #2 if #1 is feasible I plan on doing it first so the joists hangers in #2 will be attached through the plywood to the beam.

Thanks for reading!!

 

I wouldn't worry about those cracks. That is typical of large beams. You will see that in any timber frame structure.

Check out this link: 6 Ways to Stiffen a Bouncy Floor - Fine Homebuilding Article

I like the version that uses the metal strapping.

 

Tree trunks to hold up that beam may look cool but it also makes a great ladder for termites, As the trunks rot there going to fall apart and sink.
That beam also should have had far more support along it's length, with full footings and piers or lolly coloums.
Also if someone dug out that crawl space why close to the outside walls did they get. If there's nothing supporting the outside walls there's a real danger of the walls also sinking.

 

Thanks for the replies so far!!

The tree trunk beams are in footings. The is also a concrete slab floor. Basement wall is now a double wall: Blocks outside, brick inside. Sitting on old concrete footings which are now on bench footings.

There are no termites in the house and the trunk posts show no signs of rot. If anything they are very dry just like the old joists; dry but very sturdy/dense.

Not sure why you say the beam should have more support.

There is foundation -> 7' <- "post" -> 7' <- "post" -> 7' <- foundation.

Oh, and house is Balloon construction if that makes a difference.

Any opinions of 8" on center joists. (well, splitting the difference of 16" OC)?

 

Did you look at that link I posted? There is an option you can do that doesn't involve more joists to take the bounce out.

 

I did. Thanks! Just like to ponder all the options.