cracked Joist?

[eyeball]

I recently gutted my basement and I was just cleaning up some of the joistswhen I saw that one of them is cracked. The crack goes on a 30 degree angle and is at about the midpoint of the joist.

As I understand general construction for houses of two story construction, there are typically single joists spaced 16" on center and for the loadbearing wall for the second floor, there is a double joist, right?

I only have one joist where I suspect there should be two, and it so happens that it is right at the point where I believe there should be joists doubled up for the load of the second floor.

To fix this, I am thinking of slowly jacking the joist that is cracked and sagging back up. I would then bold or screw a 2x10 (same as existing joist) to each side of the cracked joist. At each end of the 2x10 sisters I was also thinking of putting a (what would it be 10x14.5) members perpindicular to the joists to distribute the load to the other joists better.

My question is how long do the new 2x10s have to be and does this sound like the proper way to do it?

Tommy

[Mr T]

Can you post a pic?

[eyeball]

I am trying to upload photos, but they don't post when I submit the post. What am I doing or not doing?

Tommy

[suemarkp]

Generally, walls that are parallel to joists are not load bearing. Although you may find doubled joists under these walls, you don't always. There is usually a main girder or band joist in the middle of the house where the first floor joists terminate. The wall above this is usually load bearing. Cracks in that girder would be bad. Cracks in an individual joist may not be all that bad, but if you can fix it I would, as why push the safety factors when you don't have to. Gluing and nailing or screwing 2x10 sisters would be good. Adding the blocking can help stiffen the floor, but that may not be necessary if there is a wall above, as a sheetrocked wall nailed to the floor provides some decent stiffness.

Posting a picture would still be a good idea, as you could have something unconventional.

[mdshunk]

Here's a few general thoughts....

A cracked joist has a load bearning strength of -zero-
attaching a "patch" just over some section in the middle of the joist would need an engineer's seal to be approved, since the code does not address this type of connection.
the repair would be best if it spanned the full length of the broken joist, and would bear on other structure at both ends.
Screws have no shear strength, and should not be used for such a repair. Bolts are the recommended fastener.

[eyeball]

Thanks for the responses. Going the entire length would be a pain, but I can see how it would be the best thing to do.

The house is 80+ years old, but is it common for joists to crack?

How does 5/8 or 3/4 in bolts with 1 1/2 washers sound?

Tommy

[mdshunk]

I'd think that if you're going the entire length, connection to the old one might not even be required since it has effectively been replaced entirely.

[eyeball]

Good point MD. Since it cracked in the first place, and I am not really sure why, I figure it is best to try and make that area as strong as possible to avoid the same problem.

Thanks a lot for the comments and advice.

Tommy

[mdshunk]

Since it cracked in the first place, and I am not really sure why, I figure it is best to try and make that area as strong as possible to avoid the same problem.
If I had to make an educated guess, I'd say that it was native, non-grade stamped lumber that was improperly selected for use as a floor joist. May have had a grain defect that predisposed it to crack in that place. On the other hand, maybe your house is falling down one floor joist at a time:questionmark:

[eyeball]

Given this hell whole, your second observation might be right on point.

Tommy

[Under_Miner]

I'd think that if you're going the entire length, connection to the old one might not even be required since it has effectively been replaced entirely.

Since you can't nail through the floor to the joist, you'll have to laminate your new joist to the existing in order to prevent twisting (which may the cause of your problem to begin with). Or you could use cross-bridging or solid blocking to prevent this.