We've an old house from 1890 and are replacing rotten and wood worm eaten beams and floors.

But, whilst doing this we've found that the internal walls have been built on top of planks of wood placed on top of the foundations ... this has also rotted, but has been so compressed from the weight of the walks and the upstairs flat that they don't look like they're going anywhere!

Is there some kind of treatment I can use that may strengthen the edges of these compressed planks to strengthen what's most exposed to stop any more deterioration and crumbling away?

I'll try and include a photo as an example.

Thanks, Tim!

small section of wood supporting walls enter image description here

  • Do you know that the wood goes all the way across the wall? My first thought was that it might be a sort of furring strip that's been embedded for nailing other stuff to it. That said, they sell wood consolidation epoxies, but I have no firsthand experience to share. May 27 '15 at 3:23
  • Hi Aloysius, yes they go all the way through. They sit below floorboard level resting on the foundations.
    – mrtimdog
    May 27 '15 at 9:17

My guess about these planks are that a builder made outer walls (that are carrying the loads) first, as well as interior support walls (if any present) and then laid a wooden floor. Just then, he(she?) managed to place internal walls that were not for supportive matters (dividing into rooms) on this floor. Years passed, loads made under-wall-planks to go deeper, while floor lasted on the same level. (all that I said was assuming that builder knew better; I'm afraid that past-technologies and construction commons were less sophisticated)

No matter what was the reason, it will be nice to do something about that. Leaving this as it is may or may not cause any problems in a near future, but making a reconstruction with that good access is tempting to solve this now.
Aloysius Defenestrate put an advice in his comment about wood consolidation epoxies. It may work, though I would hesitate to use it if the plank can be accessed to water/is totally rotten. Still, given a proper support from epoxy producer, it can be worthwhile.
Another way of 'replacing' that plank (or what is left of it) is putting concrete instead of it. It is something done in monuments or to make a less-harming change within older buildings' structure. You can replace the plank with concrete partially, say - by 20cm of plank per 1m of a wall. The wall will lose some of it's support (for a short time), but I guess it will handle that at ease. After some 1-2 weeks make another 20cm replace and so on. It's best if done by a specialist and I would advise consulting these distances (20cm replace per 1m of a wall), but I think that it will make this repair more solid.

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