Uncovered rotten joists. What next?

[japher]

I'm trying to refurbish my bathroom, but (as is always the way) I keep uncovering whole new avenues of work that need to be done . The bathroom is an extension to the house, with its own flat roof. After what looks like years of leaking (before my time), we've had the old past-it felt roof replaced with a more hi-tech solution.

Unfortunately, the ceiling of the bathroom was shot from all the water that has come through it over the years (not smooth, lots of patching up, sagging at one side). Long story short - we've ripped down the old ruined ceiling and exposed the joists, however many of them are rotten at one end.

The rot is bone dry, and a couple of the joists also show signs of wood worm. Most of them are perfectly solid until they reach the last 1ft. They are just over 2m long (so quite a small room).

Here's some pics:

http://www.imagefilez.com/show.php/111839_joist1.jpg.html
http://www.imagefilez.com/show.php/111840_joist2.jpg.html

Has anyone got any advice on how this should be tackled? Is this a job I can attempt? I'm tempted to leave this to the Pros, if I do then how much would you expect to pay to sort this (ballpark ).

Cheers,
Joe.

 

[^woody^]

You will have to insert a new joist to the side of the existing, and support it off a hanger from the wall rather than build it in.

You should also cut out the rot plus an extra 500mm. Also get the woodworm treated in all adjacent timber.

Bolt the remainder of the existing joists to the new ones