Joist and rafter trimmer replacement

[blup]

Good evening - I have found some wet rot in one side of the two trimmers in the loft space which respectively support four rafters and three ceiling joists where they butt up to a chimney breast which is flush with the side wall. The loft is unconverted and unused.

The source of the damp appears to be the defective lead back gutter of the chimney.

As far as I can see the trimmers could be removed and replaced if temporary support could be given to the joists and rafters that sit on them.
How would this be achieved typically? - by acrow props in the floor below whilst the work is being carried out, or would some temporary solution in the roof space?

The trimming joist (6 x 2 ) isnot doubled up, are supported on 4 and 1/2 inch brick work with a span of approx 3.5 metres. The rafters are also 6 x 2, approximately 5 metres. The joists are at approx 16 inch centres,

Your thoughts would be greatly appreciated as I plan to put the work out quite soon.

Cheers Blup.

 

[HERTS P&D]

Fix the leak first and let everything dry out, then take it from there. Normally it doesn't seem as bad.

Andy

 

[blup]

Thanks HD, the decay seems to have occurred over time, and the wood is pretty dry at the moment. The problem is that the board under the lead gutter - where the rot set in - is connected by various timber pieces (which are themselves decayed) to the trimmers so it all needs to be repaired as a whole.

I suppose I could cut back the trimmed joists and fix them by joist hangers further back along the trimmers. It would also move the trimmer back from the exposed chimney breast. That would just leave the rafter to be temporarily supported.

I was really after advice on what methods builders would use in these circumstances, so that when I get quotes I am ready for the alternatives that might be suggested.

Blup