Unidentified structure in garden - any ideas?

[LearningByDoing]

Looking for any suggestions on when and why someone would have built a cement and corrugated asbestos structure in the garden of a 1930s property in SE London. Nothing on planning permission and pretty sure it's 1980s or earlier.

See drawing!
- 2 parallel walls of roughly 4.2m and 2.1m length, 4.6m apart, made from gravel mix concrete lined with white corrugated asbestos sheets.

- One curved wall made from corrugated gravel mix concrete but no asbestos. Dotted lines show where we think walls would have been.

- Walls are max 85cm high and don't appear to have been broken off at the top.

Theories, no particular order:
1. WWII bunker / Nissen hut (odd shape though)
2. Garden room (very low walls...)
3. Garden landscaping as its currently piled high with earth and growing a couple of trees
4. Any other ideas?

 

[just pumps]

Friend once had a Nissen hut in his garden to keep his motorbike in.

 

[bernardgreen]

I grew up in a house that had an Anderson shelter in the garden. My parents used it for storing coal and garden tools. It was a bodge job as it was not sunk the 4 foot down into the ground as was required.

 

[JohnD]

I grew up in a house that had an Anderson shelter in the garden. My parents used it for storing coal and garden tools. It was a bodge job as it was not sunk the 4 foot down into the ground as was required.

surplus anderson's were sold after the war and mostly repurposed as garden sheds, so not dug into the ground or mounded over.

the shed ones generally have an ordinary door, and the door surround in brick or timber on the inside of the arch

not the flat panel, bigger than the arch, used on the ends of the shelters to retain the mounded earth covering

 

[Captain Nemesis]

corrugated asbestos sheets.

Looks more like asbestos cement, like they used for the roof in Marley garage kits.

Not as bad as "proper" asbestos for disposing of, but care still needed.

Do you plan on removing the whatever-it-is?

 

[LearningByDoing]

Thanks for the suggestions! After about more research we're pretty sure it wasn't an Anderson shelter or Nissen hut based on the size and footprint - neither would work with the curved corner on the right and based on Wikipedia the wall lengths are all wrong.

Happy to hear you agree about the asbestos Captain Nemesis:

Looks more like asbestos cement, like they used for the roof in Marley garage kits.

Not as bad as "proper" asbestos for disposing of, but care still needed.

We definitely do want to remove it - it takes up almost the whole back of the garden which is the sunniest spot! Not sure about getting the pros in at this point. Any tips?

 

[mikeey84]

I grew up in a house that had an Anderson shelter in the garden. My parents used it for storing coal and garden tools. It was a bodge job as it was not sunk the 4 foot down into the ground as was required.

Are you sure it was an Anderson shelter? I had what I thought was one in my garden in the same configuration.

I sold it, and a local museum owner brought it, and told me surplus Anderson Shelters were sold as garden sheds in the 50s, so lots are in gardens and not sunk into the ground

 

[bernardgreen]

Are you sure it was an Anderson shelter?

It was definitely the metal from an Anderson shelter. It was there in 1947 so could have been bought as surplus. During the war my grandmother had lived alone in the house ( grandfather died in the first world war ) and maybe she never had an Anderson installed in her garden.

 

[mikeey84]

It was definitely the metal from an Anderson shelter. It was there in 1947 so could have been bought as surplus. During the war my grandmother had lived alone in the house ( grandfather died in the first world war ) and maybe she never had an Anderson installed in her garden.

Mine was made with the metal from one too, but as I say, wasn't sunk, which is an indication that its a repurposed one rather than an original

 

[Captain Nemesis]

We definitely do want to remove it - it takes up almost the whole back of the garden which is the sunniest spot! Not sure about getting the pros in at this point. Any tips?

https://www.hse.gov.uk/pubns/guidance/a14.pdf

A roof isnt too bad to deal with, and some local authorities will allow you to dispose of a certain amount for free at dumps/tips/civic amenity sites and may even offer a free collection service.

Yours might not be so straightforward, though, as presumably its cemented to the concrete, and do you have any idea how deep its buried?

 

[Tigercubrider]

Anderson. Maybe shed, maybe shelter.

Original design was to dig out a rectangle of earth a given depth, build the semi sunken shelter, then use the spoil as added protection. I believe people even grew veg on top.
Quite possibly during the war, or after, someone acquired some concrete to reinforce it, or just shore up a rusty one. Can't see why asbestos would be used unless it was acquired cheaply. We have a ww2 or later massive shed at work that was built as some kind of barn/garage that today would be steel. A shelter of garden shed wouldn't need asbestos

 

[Harry Bloomfield]

4. Any other ideas?

Look at Google Earth's photos from above, some go back quite a few years.

 

[Captain Nemesis]

Not back to the 40s...

 

[Harry Bloomfield]

Not back to the 40s...

No, but it might go back far enough to see the progress of some of it's deterioration over the years - maybe.

 

[LearningByDoing]

Look at Google Earth's photos from above, some go back quite a few years.

Is this Google earth pro? We've checked on the free one with Timeline and can't zoom in far enough to see individual properties!