What can I do about a joist sat on slightly rotten wood?

[Gary111]

One of my joists seems to be packed underneath with slightly rotten wood.

What's the best way of dealing with this?
I was thinking maybe I can support the joust, drill out the wood and try to get some mortar in the void?

Seems tricky though.

 

[Wayners]

Pack with Slate

 

[foxhole]

You could tap in steel shims, depends how thick packing is.

 

[JohnD]

Have you rectified the damp yet?

 

[Gary111]

Ok thanks, yes I've sorted the damp

 

[Gary111]

But one of the joists reads 21/22 percent moisture just on a small area.
This area looks solid.
Is that something to worry about?