Why would this 100 year old house collapse like this?

[bibbitybobbityyhat]

This story caught my eye because it is quite near me and I walk through street after street of London terraces like this every day.

I can't remember anything like this ever happening before.

not a Daily Mail link

SE London clay is a bugger for subsidence
dodgy ground + dodgy builders can't be a good combination

we elsewhere in the country live in an old house in an area known for subsidence due to mining. every now and then we ponder on knocking through from the galley kitchen into the dining room, and always chicken out due to fear of upsetting what's probably a very finely-balanced load on ropey ground...

Cracks in a victorian house don't necessarily spell disaster but should be monitored.
We live in an area of clay soil that can have significant movement depending on the weather this is fine in most of the house but as victorian bay windows often weren't built with a foundation the movement is more obvious at the join and we have a crack that appears here when it's dry but as soon as it rains closes up again. It's been doing this for probably 140yrs (definitely 30yrs according to neighbour who have the same crack) without any actual problems except for the decor

Another one today
Penarth house collapses during basement extension - www.bbc.co.uk/news/uk-wales-south-east-wales-36502418

Maybe...

Dr specialising in botox and fillers? And there was me thinking it would be boobs.

house near my children's school is having a massive basement dug out - a few weeks ago the whole thing collapsed internally. It is an old church. It clearly wasn't designed to have massive cinema room and pool beneath the vestry. The damage was incredible. The whole of the two floors (of previous conversion) have gone.

A lot of older properties have shallow foundations by today's standards. One of the reasons why digging out a basement where there wasn't one previously can be risky.

My mate bought an old Victorian terrace some years ago, around the time of the first wave of Eastern Europeans arriving. He wanted to make some changes and a very nice Romanian man arrived to quote. This man told him cheerfully they could knock this and that wall down, no problem.

Mate fortunately got a second opinion. English builder turned up and said if he removed one of those walls, the chimney would fall into the house and probably take my mate with it.

The English builder just knew that kind of house like the back of his hand, having worked on them his entire career. He saw lots of things that weren't obvious to the naked eye.

I can imagine a lot of people working in London construction during this property bubble (whatever their nationality) are just crossing their fingers and hoping rather than having real knowledge. Competition is fierce and everyone knows it can't last, so there is a 'get rich, quick' mentality all round.

The owner should not have started without approval from the Building Control Inspector. This is what the Inspector prevents.

The Lewisham house was under Building Control supervision and had the relevant planning permissions in place for the internal alterations plus an extension at the back. They've now got a new application in to replace the collapsed roof and front facade. Feel very sorry for the couple involved here, hope they get it sorted.

You can remove internal walls if they are genuinely non-load bearing, and/or you put an RSJ loadbearing beam in where the wall was.

My grandad's house has recently been re-developed, and it's a late Victorian town house, 4 stories including basement. I was quite horrified to see that ALL the internal walls had been removed in the basement (not in the upper floors though) but the builders did know what they were doing in that case and the RSJs were put in. It's still standing! (Also a terraced house, but mid-terrace rather than end terrace, which would also make a difference as it has a house on either side to help hold it up.)

Sounds like this was a bunch of cowboys who have now ruined a very expensive home! AND probably made the next door home structurally unsound in the process.

You can take out loadbearing walls and replace with RSJs, but you need to put in temporary structural supports in the mean time.

house near my children's school is having a massive basement dug out - a few weeks ago the whole thing collapsed internally. It is an old church. It clearly wasn't designed to have massive cinema room and pool beneath the vestry. The damage was incredible. The whole of the two floors (of previous conversion) have gone.

Yikes, what a mess

You can take out loadbearing walls and replace with RSJs, but you need to put in temporary structural supports in the mean time.

Putting in a steel beam to replace the wall only does one part of the job that the wall was potentially doing - taking the weight of what is above. But the wall could be providing support in other ways, such as horizontal stability. It doesn't mean that you can't take the wall out but you may need to do other work too, such as putting in a 'goalframe' sort of structure. Foundations may also need looking at.

I often get people calling up saying they want a beam design for a wall removal, but don't want to pay me to go to the property and check it out properly. The beam design itself is simple, spotting other issues maybe not so much.

And yes, temporary supports are usually needed and are often the most difficult part of doing the work.