Reassure me - foundations of old lean to extension

[Cellophaneskies]

Hi.

My house is mid 60s. It’s had a lean to extension installed at some point in the past. It’s single storey, flat roof, roughly 3x3m. My neighbours tell me it has been around since at least the mid 80s, so it has been standing for a long time.

It’s all square and true outside, but weirdly the bottom half has been rendered, and that is very wobbly - some of the render depth is shallower than the brick above it so I suspect that’s hiding something.

I was wondering how secure and stable this extension is. On both sides, one spot on each, I have dug into the earth and I can actually dig under the wall in that spot! As if it has no foundations and is sat on the earth at normal ground level.

Now this seems weird to me. Surely if that was the case, it would have sunk by now, over the course of fifty years, if the foundations weren’t solid.

Is there some non-usual construction technique that may be supporting this? Perhaps a metal frame supported at corners or something similar?

obviously without knocking it down or digging it out it’s hard to tell, but i thought I’d ask here in case this sounds normal or indicative or some sort of unusual construction type.

Thanks!

 

[tony1851]

You need to post a few pics - hard to understand what's going on.

 

[Ivor Windybottom]

Dig out alongside it. If this is enough to make it fall down then you've answered your own question!

It should sit on concrete, which should sit on clay, sand or rock - not black topsoil.

As it's only 9sqm then if it's substandard you could either not care about it or replace it. It's very unlikely to make sense to try and fix it. It's very expensive to build downwards under something. If they didn't bother with foundations then you can guarantee there will be many other issues too.

 

[Cellophaneskies]

Reviving my thread as I’m curious again. Photos attached this time of where I have done small test digs..

One corner. The left wall is the garage. The wall on centre of frame is the bottom of the extension. At first I was reassured I was seeing bricks deeper into the groin but then the appear to end just two bricks below ground level

Hole I dig with a trowel under the extension. The concrete around the edge I think is added after the extension, it doesn’t seem I have an equivalent on the other side

Small hammer for size comparison

Brickwork underneath the crabby rendering. This is an old photo, I can’t recall if the flat concrete under the bricks is still there or not. I chipped some out in the past as it was like 2cm thick and appeared do be added after the extension

 

[Ivor Windybottom]

Looks like junk, but as you say it hasn't fallen down so presumably the soil is holding it up OK.

I guess your approach depends on whether you need to eliminate future risks or not - probably whether you're going to live there for ever or tart it up and flog it on at some point.

 

[noseall]

Reviving my thread as I’m curious again. Photos attached this time of where I have done small test digs..View attachment 379183
One corner. The left wall is the garage. The wall on centre of frame is the bottom of the extension. At first I was reassured I was seeing bricks deeper into the groin but then the appear to end just two bricks below ground level

View attachment 379184
Hole I dig with a trowel under the extension. The concrete around the edge I think is added after the extension, it doesn’t seem I have an equivalent on the other side

View attachment 379185
Small hammer for size comparison

View attachment 379186
Brickwork underneath the crabby rendering. This is an old photo, I can’t recall if the flat concrete under the bricks is still there or not. I chipped some out in the past as it was like 2cm thick and appeared do be added after the extension

It's a low-end structure built upon either a slab or shallow strip foundations. Initial thoughts are the ground looks good, but that could change.

What is your actual query or issue with the extension?

 

[Cellophaneskies]

It's a low-end structure built upon either a slab or shallow strip foundations. Initial thoughts are the ground looks good, but that could change.

What is your actual query or issue with the extension?

My main reason for asking is that I want to relay patio next to it. Which would involve digging down 10-20cm or so beside it for the sub base or drainage channels to be laid.

I’m paranoid that disturbing it more would cause issues. But then I imagine the garden has been through many changes in the last 60 years and this has (supposedly) been standing since then.

There is some rough, wobbly rendering around the bottom third, only at the front, which I suspect is covering some sort of bodge or issue..! But I’ve been here for 9 years and I was concerned about it from the start, and I’ve not seen any changes to its structure in that time

 

[Ivor Windybottom]

Do it, if it falls down as a result of some soil being moved next to it then you needed to find this out.

 

[Cellophaneskies]

Do it, if it falls down as a result of some soil being moved next to it then you needed to find this out.

Fair. Bloody thing. I darent spend too much on it or around for fear it will sink but it’s been fine for so long it’s sort of proving its worth despite the general crap factor.