Strange wood layer in base of wall?

[randomfactor]

Hi,

I'm a new member here, but been lurking/browsing for a few months reading up. Hello everyone

I bought a small old end terraced cottage (built ~1900) a few months ago that needs some work (more than I originally anticipated by the looks of things).

As I'm ripping off plaster and pullling up floor boards etc., I've run across a few things that have me puzzled. Had a guy out to have a look at things for me to give me some advice. He's more of a carpenter than a builder - but he's been involved with the building trade all his (fairly long) working life and he's helped to point me in the right direction in a few places, but this one has him a bit puzzled too:

After ripping up layers of carpet, underlay, lino and hardboard I found damp and (active) woodworm damage to the floorboards of areas of the living room, so in the process of investigating, pulled up a few floor boards in the corner of the room next door to it to check the joist ends and have a look under the floor.

I found what appears to be a wood plank running the length of the (solid brick) internal wall. While most of this wood layer (of the parts I've got at to check so far at least) seem sound. The end closest to the corner was crumbling and rotten.

I'm confused. Anyone got any idea why it's there in the first place?

It looks to be part of the original buildings construction, but I can't be sure.

My first thought was to try to remove it in small sections, lay sections of damp proof material and fill with mortar (or some other hard/strong water/rot resistant material) bit by bit. But the guy who looked at it with me thought it might be best left well alone and treat.

I'm not sure if this is the best course of action? Or what it's best to treat it with?

I'm trying to do things properly so they'll last well into the future, and leaving a layer of wood in there in a brick wall seems like a future weak spot, particularly as it has a (currently) poorly ventilated under-floor sitting on an unsealed earth base.

What would be the best course of action to deal with this?

 

[vinn]

What you describe is a "built-in plate" & it was a common building practice 100+ years ago.
Plates might run internally or around the external walls of the building.

We always remove all trace of such plates, even where they appear sound, and, after chemically treating the recess with anti-fungal chemicals, infill the chase with masonry.
There's a slight danger that, without adequate under-floor ventilation, wet rot can turn into dry rot, & you dont know what fungal activity might be taking place at the"back" of the plate.

Any joist tails sitting on these plates might possibly also have rotted, and need remedial work.

Why not post photos the areas of concern & if you want help with any remedial works then come back here.

 

[randomfactor]

Thanks Vinn. That's very helpful, and your approach sounds much better to me than leaving it there.

I spent ages trying to find information about this online, and didn't have much luck, but you mentioning it's called a built in plate has helped to bring up some results. That does indeed look like what it is.

I haven't moved into the place yet, and it'll be a couple of days before I can get back there to take a photo, but I'll post some up here as soon as I can.

I haven't noticed these plates in any of the external walls yet (thankfully), just this one internal wall so far. Though there's still some more areas to look.

I was eluctant to dig very much of it out in case it was bearing any load (the rotten bit I did dig into with a screwdriver seemed to go very deep into the wall ). I'll try to see how deep into the wall it goes the next time I'm over there.

The (currently) non-existent underfloor ventilation is something I'm also going to have to sort out, but that's a whole other awkward story in itself.

 

[womble69]

What was the purpose of such a thing?

 

[randomfactor]

The only thing I can think of is that it was to lay the joists on, though why it runs the whole length of the wall even where there are no joists, puzzles me, so I may be wrong?

I'm going back over there later today so I'll try to get some photos to post up.

 

[Gerrydelasel]

Maybe it was to nail the skirting to, but they installed it a couple of courses too low!

 

[vinn]

They were built-in with the belief that they would bond the wall or the whole structure.
Like a belt they were supposed to keep it together.
How that would work I dont know but the old ones were anything but fools so there must have been something in the practice.

 

[stuart45]

Timber was sometimes used as the external bricks could be a different size to the ones used on the inner walls, so the odd timber course was used as a levelling course.

 

[theprinceofdarkness]

Err, No joists in pics, I thought that the Edwardians chiseled out a slot on the inside face of the wall, inserted your long straight bit of wood then put the joist end on it ("wall plate" ). This then set all the joists level, perhaps using better skilled crafts the using brickies to set all the joist end level in holes in the brickwork. If the joists are fixed else wise just take the wood out, it will only encourage damp and rot.
Frank.