Do I really have no footings?

[Sunshine99]

Just started on a zebcolm trench (ish) project. This is a three storey 1840s house, which has been much altered (ground levels changed, major changes to the landscaping) in the past. On the face of it we had a perfectly normal brick wall, with a flat gravelled area running up to it. We start to dig and find this. Can anyone offer any pointers as to what's happened here?

 

[Sunshine99]

Adding for clarity ... it's not the whole house, just one corner. Digging elsewhere I find the bricks carry on downwards as one might expect.

This has probably arisen because of earthworks carried out by the previous owner - this part was previously several feet below ground, and I am thinking that when they excavated they went a bit too far. Do I just quietly fill in the hole and pretend I never saw it, or do I need to pay someone to look at it?

There's clearly no point in making a ventilation trench if there aren't any bricks to ventilate!

 

[stuart45]

Does the rest of the house have footing courses, where the brickwork is spread out each course a bit more for a few courses to spread the load?
Are there any signs of movement in the brickwork in that corner?
You definitely don't want to dig down any more.
Walls generally settle for a number of years when first built and then stabilise. It's only when the situation below changes that more movement happens. For example leaking drains, new tree roots taking moisture.
People often worry when they find that their house has shallow foundations, but walls built with lime mortar could normally cope with the movement, especially if it was reasonably even over the footprint. The movement normally stops in time.
If a building was badly designed you could get what is known as differential settlement, which was sometimes confused with subsidence.

 

[malcolm]

I have a wall like that. It started off as a lean-to in the 1700s and was built up to 2 storeys in the 1800s.

Mine does have the trench running past. I filled the bottom with concrete to resist any sideways movement from the soil under the bricks. You only need the bottom of the trench a couple of bricks below internal floor level.

 

[Sunshine99]

Thanks for the responses. The house is on sloping ground, we're looking at the "high" side here. What seems to have happened is that the bricklayers, nearly 200 years ago, saved themselves a bit of time by laying fewer courses on the high side ... working along this wall at some point another course appears, and then further along another one. That wouldn't have bothered anyone at the time because the high side was then backfilled.

Then, 20 years ago, a lot of that backfilling - and a lot more besides - was excavated to give a level area at the back of the house. My view today is that they excavated just a little further than they should have done in the pursuit of a "perfect" flat area. The interior floor level was lowered as well, I think.

The additional layers along this side of the house are indeed set out as footings, protruding half a brick from the main wall surface. Its just this section (and actually probably a bit more that I can't see) that is missing these footing courses.

If the house were unmodified since it was built then I'd be happy to take the view that it has stood all this time and is likely to stay that way. But the work carried out 20 years ago may have had the effect of undermining it. Having said that, I can't see any sign of the bricks having dropped out of alignment.

 

[Sunshine99]

I have a wall like that. It started off as a lean-to in the 1700s and was built up to 2 storeys in the 1800s.

Mine does have the trench running past. I filled the bottom with concrete to resist any sideways movement from the soil under the bricks. You only need the bottom of the trench a couple of bricks below internal floor level.

That would be nice. There aren't two bricks below the internal floor level at this point - just one and a tiny bit. Hence abandoning the idea of any meaningful trench at this point - I am currently thinking I might just put the soil back to about half way up the brick and then just put gravel.

What that leaves, though, is uncertainty about stability - the idea of dumping some concrete there is a distinct possibility.

 

[stuart45]

The weight of the house goes down to the bottom of the brickwork, and then is transferred to the ground at an angle of around 45°. This is known as the angle of repose. As long as you don't dig this area away you won't have an issue. It looks like you've taken a couple of inches of it away, so a bit of concrete might be a good idea.