Damp beam in the middle of the house
RogW
| Posted in General Questions on
Hi, I’ve got an old house (probably in excess of 200 years) through the middle there is a beam sitting on a couple of courses of bricks. I’ve noticed that the bottom of the beam is wet and starting to crumble (although it could have been like this a very long time) The wooden floor was replaced with concrete about 35 years ago. I am assuming that the water is coming up through capillary action. I was wondering if there was a substance to stop the rot and seal the beam?
Many Thanks
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Replies
Roger,
We need more information. Is the beam in a crawl space, a basement, or in the conditioned area of your house?
When you say "the wooden floor was replaced with concrete," are you talking about a crawl space floor, a basement floor, or a floor that is part of the conditioned area of your house?
Roger,
Is the beam supporting your first floor? (If so, it is probably in your basement or crawl space.)
Or is it supporting your second floor? (If so, it is probably in your living room or kitchen.)
Is the concrete slab below grade (that would be a basement slab or a crawl space slab)?
Or is it above grade (a slab poured over subflooring and joists)?
Ah right, the beam is at floor level, the concrete slabs have DPM that come up and finishes at the bricks.
Roger,
I didn't notice the photo before; now I see it.
That looks like the bottom plate of a wall, not a beam.
Yes the beam is supporting the first floor, this was between the old kitchen and the living area, the old Kitchen floor (bricks on sand) and the old living area (approximately 1 foot under the old wooden floor) were both replace with concrete on top of a plastic membrane.
sorry this appears to have loaded twice
Sorry, yes my poor knowledge of terms yes it is the base plate of the beams of the dividing wall that had the lathe and plaster removed
Roger,
I'm going to translate; tell me if I have it right.
The bottom plate of a partition wall in your old house is sitting on bricks in contact with soil. On either side of the bottom plate, concrete slabs have been poured, but the concrete slab does not extend under the partition with the rotting bottom plate.
Is that correct?
That's what I was trying to say, thanks
Roger,
If the partition is load bearing, you need to excavate a trench under the wall and pour a new concrete footing to support the partition. The footing would need a capillary break and/or polyethylene to prevent wicking, and the new bottom plate would need to be pressure-treated.
If the partition isn't load bearing, you can remove the rotten bottom plate and replace it with a stack of new pressure-treated 2x4s or 2x6s. Don't forget to install polyethylene under the bottom-most plate.
Thanks Martin,
Wow that sounds like the nightmare I was fearing, yes it is load bearing, so it's the whole nine yards.
Thanks for the advice. I was hoping that I could find something to harden the wood - I guess it's time to talk to the bank manager.
Rog
I'm not sure Martin has called this one correctly. Is this home located outside of the US by any chance? This not not standard North American stick framing, these are heavy timbers, oak I'd guess, and as such they can often be repaired and stabilized by resin injections which will also prevent further wicking of ground moisture into the assembly. I recommend you contact an experienced historic repair specialist for an assessment before you start in on expensive invasive procedures based on an internet diagnosis. And I would only undercut the assembly to install a new footing if the structure above is showing serious signs of recent movement via growing cracks in finishes etc. A big ground beam like that can often be sufficient to transmit a fairly substantial evenly spread load to the ground so long as it's protected from decay. I would also check the external perimeter of the house to identify any addressable source of water intrusion. If the beam had been wet for two hundred years it would have rotted away long ago. What has changed recently? Is there ponding, are there changes in surface water dispersal from adjacent development? Are there rainwater pipes discharging directly onto the foundation?
Thanks James, yes we are in Essex, some 40 years ago we replaced some of the front of the house and am convinced that is OK the back has been replaced with part of an extension so that should also be OK. I am going to look into stabilising the oak and possibly enlist a building expert. It's probably been like it for the entire existence of the house (cottage) which I believe is in the region of 250 to 300 years.
Rog
James,
Thanks for your comments. I agree completely that Roger shouldn't make any decisions based on an internet diagnosis; that's a good caveat for all GBA readers to remember. I'll be the first to admit that I am not experienced at renovating English oak timber frames.
Here are a couple of observations: Roger has had a few problems with his home's wooden floors -- problems that were serious enough to lead him to pour concrete slabs to replace the historic floors.
Roger also apparently had enough worries about this load-bearing wall that he decided to remove the lathe and plaster from the wall (unless, of course, the plaster was removed for aesthetic reasons). These clues lead me to suspect that Roger's rotten bottom plate may need more than resin injections.
I'll offer no more opinions on this matter, however. The best advice will come from a local contractor experienced in historic renovations.
Hi Martin, you are right It was the lathe and plaster was removed for aesthetics, I'll come back when I've had another think and taken some local advice.
I am very grateful for both yours and James advice on this, money is tight so thoughts have helped my focus..
Very Very many thanks.
Rog