Lime mortar against inside of syllstock?

Svensk översättning längre ner.

When removing and patching rotted material from our syllstock, we found that it had been partially patched from the interior side of the wall with lime mortar, making the sill log not as thick as the other logs in places.

Unfortunately I didn’t think to photograph the spots before patching them. I don’t know how far the line mortar against wood goes (I’d need to pull up flooring to see).

Advice?

We can also see that this lime mortar encouraged the syllstock to rot from the inside, in some cases leaving a hard looking shell on the outside and rotten material up against the mortar itself.

We had a timmerman come to evaluate damage previously and he said we could go with short patch sections. Now I’m not so sure and wondering if we might need to put jacks on the wall and do a full syllbytt. The wall is holding but the rot damage extends more than halfway through the log in multiple places.