repairing floor joists

[simba1903]

I am repairing a rotten floor joist from where water has come in under the door. I don't really think its necessary to rip up all the floorboards and replace the entire joist as its only rotten where the door is which is obviously where the water has come in.


In such a case what is the procedure for joining a new joist in? (opposed to replacing the entire joist)
Can the join be made in the air? as in not above a floor plate.
I realize the repairing as opposed to replacing means adding a new joist and bolting to old.

 

[foxhole]

What are your joists sitting on? brickwork, hangers, timber?

 

[ladylola]

In such a case what is the procedure for joining a new joist in? (opposed to replacing the entire joist)
Can the join be made in the air? as in not above a floor plate.
I realize the repairing as opposed to replacing means adding a new joist and bolting to old.

Think you've pretty much answered your own question in the last sentence . It's perfectly possible to bolt a piece on in mid air so to speak , there's no absolute necessity for the new timber to stretch from one wall to another although if one wants a belt and braces approach then a full length would be the answer.
If the new piece is bolted with a minimum of three bolts then it shouldn't deflect. In practice use more than three bolts and stagger them rather than siting them in a straight line.
Another alternative but probably unnecessarily expensive and complex for your job is to use a steel shoe again bolted in place. I've done both in my time along with other methods such as internal steel plates and have even seen repairs made with glass fibre rods and resins.

 

[ladylola]

//www.diynot.com/diy/threads/joist-repairs.229109/

One of mine from some time ago.

 

[SFK]

I also found a good response when I posted a similar question a few years back:

//www.diynot.com/diy/threads/wood-wall-plate-or-concrete-wall-plate.353169/#post-2666135

And a nice photo of the rot that I found.
sfk