Wooden wall plate 'embedded' in wall

[info_45]

My terminology might be a little bit off here, so apologies.

I discovered a slow water leak in the mains pipe leading in the hallway of my Victorian terrace. I don't think this is related to the problem I'm about to describe, though I can't be 100% sure of that, but it led to couple of floorboards being lifted in the hallway to get some air to the subfloor and allow a repair to take place.

I'll say at this point that that subfloor is not well ventilated. I asked someone to drill some holes through from under the front door, but it seems that they didn't actually achieve this.

Anyway, on one side of the hallway, the party wall, the joists seem fairly robust and are sat on a wooden wallplate. This is shown in the final photo below This seems pretty dry and there is a gap above the wallplate as though it is placed on a lip in the brickwork below. On the other side, the internal wall, its as though the wallplate is wedged between a layer of bricks. The joists sit in a little gap between these bricks on the wallplate and that wallplate is damp and rotten. I'm not sure how far into the wall the joists go, but you can see that the ends are also rotten. There is no bounce in the floor, but clearly there is or has been some water ingress. If I look a little further down the hallway, the wallplate is still under brick but, visually at least, it appears to be dry and its this fairly isolated section where this wood within the bricks is wet.

At the moment I haven't taken off the skirting board so I can't lift the other floorboard to get a proper look. Its still getting some airflow, which is more than it would have had for a long time.

So a few questions buzzing round my head (but general commentary welcome!)

1) why would they have put bricks on top of the wall plate, and why would the joists sit 'within' the wall? It doesn't match the other side, but also doesn't obviously look like its some sort of more-modern variation. The bricks seem to be flush to, as though the bricks above are actually placed directly on to the wood and this has been done deliberately.

2) It looks like the area has been damp and obviously the source of the damp needs to be located. I'm not sure what that source is. I'll also try and actually get someone to install an airbrick, though its a real mess of materials under the front door so not sure how that can be achieved. But this bit of wood is completely rotten. How do you go about replacing it if there are bricks above?

Picture one shows the first joist as you come in through the front door, along with the real muddle of stuff that is under the front door. The green and yellow cable is come kind of bonding cable, that comes in from by the front door.

 

[Cubist]

Its very common to find joists mounted in 'pockets' in the brickwork of older properties and heavier timbers embedded in walls that may form key elements of a suspended floor or to carry other parts of the buildings structure and features such as bay windows and door openings. Sometimes these heavier timbers were also used to carry brick or lath and plaster internal walls above the apparent internal floor level. Timber rot and decay problems typically arise near the end grain of such timbers as the grain structure provides a readily available, and highly efficient path for water ingress into the body of the timber - you might be surprised by just how far such water can penetrate along the length of the timber without being externally evident. Airflow is always vital and a single air-brick will not be sufficient, a second will be needed to ensure effective air-flow through the void. The key though is to track down and eliminate the sources of any water coming into contact with the timbers and you should look first to external walls in which the timbers are embedded if there are no other water sources.

 

[info_45]

My first thought is perhaps water seeping in from the outside somewhere.

A stonemason was working on the front of the house last year and said that water did pool a bit in the area roughly outside of there. It was also a bit exposed whilst the work was being completed, so a possibility of water having got in a bit. Given the lack of ventilation, its quite hard to know then whether this is ongoing or if it got wet last summer and hasn't been able to dry out.

On the subject of an air vent, I just had a closer look at what's under the door. I'm wondering if this is some mess of concrete that was dumped in here when they redid some of the path outside (no idea when). Those blocks in the photo below actually look like they could be the old tiles that used to be outside! Might I have expected this to just be bricks? How on earth might you approach putting in an airbrick (or two)?

 

[fernicarry]

As I understand it those thin wall plates as you describe them were used at construction time to spread out the point loads introduced by the joist ends whilst the mortar in the wall went off. My upstairs joists sit on a wall plate embedded in the masonry, so the masonry between the joists sits on the plates too like your first wall. Downstairs the wall plate rests on a sleeper wall with nothing in between the joists, like your second wall.

If they have rotted out and are no longer supporting the joists ends you can pack pieces of slate in instead. If the masonry needs support then clean out the remains of the rotten plate and pack mortar in. If the joist ends themselves are gone then they'll need to be cut back and new timber sistered in place.

 

[info_45]

As I understand it those thin wall plates as you describe them were used at construction time to spread out the point loads introduced by the joist ends whilst the mortar in the wall went off. My upstairs joists sit on a wall plate embedded in the masonry, so the masonry between the joists sits on the plates too like your first wall. Downstairs the wall plate rests on a sleeper wall with nothing in between the joists, like your second wall.

If they have rotted out and are no longer supporting the joists ends you can pack pieces of slate in instead. If the masonry needs support then clean out the remains of the rotten plate and pack mortar in. If the joist ends themselves are gone then they'll need to be cut back and new timber sistered in place.

What I like about this is that it makes things sound very simple! Having a few floorboards up does make it seems less daunting as something to deal with, rather than just the unknown in the void below. Is there are way to know whether its supporting the masonry or not?

 

[fernicarry]

Is there are way to know whether its supporting the masonry or not?

I'm guessing the bricks sitting on the wall plate are the inner leaf of the wall, but I'm not very familiar with brick construction. If in doubt then getting a bit of mortar in there, possibly with small stones or bits of slate bashed in to reduce the volume required, should be pretty straightforward.

 

[Stevers]

When I was sorting the sodden corner of our living room where there were some Victorian French Windows that are not quite original to the house, I found an airbrick under the door cill that was clearly expected to communicate with some sort of void under the large slab outside that presumably had once been a step. Needless to say the worms and other critturs clearly weren't informed of this and no void remained when I investigated. I added an air brick to one side of the doors and the damp smell in the floor void disappeared almost overnight.

To compound the issues I had, there were two other air bricks in the front of the building and these were in front of some panelling in the window splay and the narrow gaps left under the floorboards for air to circulate were also blocked with over one hundred years of dust, dirt and cobwebs.

 

[fernicarry]

with some sort of void under the large slab outside

We had the same arrangement. A window that had been cut down to be a door and a slab poured in front of it with a sort of tunnel inside it made up of bricks and slates. The tunnel itself was still clear but the exit had been blocked by the lawn advancing over it. Now rebuilt with two air bricks under the door cill and the paved area lowered. I can feel air movement through the bricks on the back of my hand.

Maybe the OP could post a picture from the outside of where he wants to put the air brick.

 

[info_45]

Apologies, I didn't get a notification of these responses. I'll get some photos of the possible airbrick location and post.

 

[info_45]

So, this is from outside. The path immediately in front of the door has clearly been replaced at some point. It looks very similar but the tiles are thinner and don't quite match those infront of the rest of the house.

The holes in the centre of the sill were drilled through last year, with the intention of adding ventilation. Unfortunately I didn't take the floorboards up to actually check what they led to inside and it wasn't the void space. There was no airbrick prior to this. I'm wondering whether at some point the door sill was replaced, maybe at the same time as the path was relaid, hence that mess of concrete inside (previous photos) which also seems to have some of the original tiles are stuck/embedded within it.

Ground level (i.e. the tiles) is probably just about below the underside of the joists. But, if you went horizontally from the face of the door sill (outside) you would hit the first joist in the hallway. That's the joist which I've shown in the photos. That would also be perhaps double or triple the width of an airbrick anyway. If anyone has any suggestions for how best to get some ventilation in there with this arrangement it would be appreciated. If there was some fix that didn't involve lowering the ground outside then that is much more likely to be workable at the current time. This seems like a telescopic air vent might work as a concept, but I'm not sure if those are really designed to go through a solid wall as opposed to a cavity wall.

 

[Stevers]

There really should be a gap between that joist and the wall. Those terrazzo style tiles don't look original, so I reckon it's been messed about with.


In our case, even though there had been a gap between the outer joist and our front wall, it had filled with 120 years of dust, dirt and cobwebs. As a result the whole length of joist was damp, wet rot had taken hold and it was very wormy where it was against the wall. Rather than mess about, I replaced the entire 30' run of joist along the front of the house with new treated timbers on DPC where it sat on the stone sleeper walls and ledges. This is the new joist going in where it runs in front of the window splay in our living room - five years into our renovation. The halving joint being from when I tried to replace just the end and then thought better of it. I added the batten on brick pads so that there was something to fasten the floor boards to in the splay, something that the Victorians didn't seem to think was necessary. Either the floor had dropped, or the panelling had risen - requiring a significant gap to be filled for the floor to be level into the splay!

Thinking of @Coles quest for 'natural' looking wood, that nasty looking white panelling was subsequently oak scumble grained with only minimal paint stripping.

 

[fernicarry]

Tricky one. Best I can suggest is removing the weather bar/wooden cill and see if you could gently lift the tiles for a bit more an exploration (not sure if that is even possible, it looks like a PVC door so the whole frame and weather bar might have gone in as one unit). Find a way to go down through that concrete and out under the noggin that carries the ends of the floor boards. Cut the upstand tile and set a metal air brick in for sufficient air flow.

Or is there any easier way to the side of the front door?

 

[info_45]

There really should be a gap between that joist and the wall. Those terrazzo style tiles don't look original, so I reckon it's been messed about with.

Do you mean a gap at the ends of the joists? My best guess if that there isn't on the side where I can see water has got in, but I can't confirm without removing more boards. Where I've highlighted the first joist in my post, there is a tiny gap - maybe 5mm - between hat joist and the sill. Its just full of dirt and dust.

And yes, I think this has probably been messed with. I'm not sure if the terrazzo style stuff is tiled though. When the holes were drilled through last year, the guy suggested it might be some kind of resin bound blocks. Again, not quite sure what the terminology is!

Tricky one. Best I can suggest is removing the weather bar/wooden cill and see if you could gently lift the tiles for a bit more an exploration (not sure if that is even possible, it looks like a PVC door so the whole frame and weather bar might have gone in as one unit). Find a way to go down through that concrete and out under the noggin that carries the ends of the floor boards. Cut the upstand tile and set a metal air brick in for sufficient air flow.

Or is there any easier way to the side of the front door?

As above, I think they may not be tiles but rather some sort of resin-bound block. As you've said, its a PVC door so tricky to remove any bits or get underneath.

It might be that a bit of skirting and the floorboard against the wall can be removed, to get a look from above.

So far my best option for getting ventilation in there (which is slightly separate from how the water is getting in, but will be a good thing to do nonetheless) is a periscopic vent. There is otherwise no way at all for the air to be moving under there.

 

[Stevers]

Do you mean a gap at the ends of the joists?

There should be a gap between the sides of the joists and the wall. Mine was full of rubbish, it doesn't look like you have one for air to circulate. I've never given terrazzo much thought as to what it was, I had I suppose assumed it was a posh concrete requiring a cementitious binder, but they can also be polymeric or use both - so I'm none the wiser as to what yours are, but they do go back a long way in some parts of the world.