Victorian floor joists - the repair of.

[stevesee]

2 joists have been cut short by about a foot from the wall. I intend to marry up a 4ft or so section to the side of each one and to the wall with joist hangers. The existing joist measures 170mm by 35mm, an unusual size. Should I just use a 2 x 6 length, if I can't get a 170 x 35?

 

[tony1851]

As you are near the end of the span, a smaller-sized joist will be no problem and 6 x 2 will be fine. What you do have to watch out for is how you fix the new length to the existing joist. The main ways are 1). bolts (or just threaded bar cut to size) and 2). coach screws.
I would be inclined to use a minimum of 4 fixings, suitably spaced, and not too near the cut ends.
A more robust method is to use toothed connectors, which bite into each face and give a good mechanical grip. The problem with these is that they are hard to fix. You have to pull the timbers together with a high-tensile steel bolt first, and when they are tight together, remove the bolt and replace with an ordinary bolt tightened up. (if you try and tighten them with an ordinary bolt, you will just strip the threads)