A bit of rot...are these joists ok?

[hexdex]

OK, so I'm completely renovating our downstairs bathroom. The house is an old Scottish traditional building of granite with lath and plaster walls. One of the effects of lath and plaster was for the plaster to slip down behind the laths during application and onto the underfloor joists encasing them in a nice porous bed of plaster bridging onto the external granite wall which unsurprisingly attracted some rot in the joist ends.

In the picture below you can see one of the worst affected joists with all the rot cleared away. What remains is dry and solid. In fact most of the affected joist was actually past the load bearing section as you can see as it sits on a plank of wood with a damp proof layer of slate underneath. The white residue you can see on the joist is actually remnants of the plaster bed it sat in. The whole area is bone dry. There is also plenty of underfloor ventilation.

So my question is will these joists be ok to leave now I have stopped the cause of the rot? Or do you think it would be worth sistering a length joist just in case? I'll be giving them a good dose of preservative and insecticide as well of course.

Thanks.

 

[vinn]

If you are happy to leave the joists and plate as they are, & are sure that all is dry and sound then dont do anything else.

However, I always remove all signs of wet rot damage.
I would be suspicious of the plate and deeply probe it near the wall side.
I would also probe all the affected joists for about 600mm back from the wall.

 

[hexdex]

Thanks vinn. I'm actually surprised at the short distance of the rot given over 100 years of sitting in a damp bed. They don't make timber like they used to....

I will be fully cleaning and treating all the joists ends today just to be sure. But even the plate appears solid apart from a little bit.