Potential subsidence in new house

[deshg]

Hey everyone,

Myself and my girlfriend are buying a Victorian house in North London (Hackney). It's a 3 bed house with the equivalent of a 2 storey extension on the back (but it's not an extension it's original from when the house was 1st built). In the kitchen (at the back on the ground floor) is a dip of about 6" at the centre in the middle of the floor from side to side. We thought this was subsidence but have just been to the neighbours (with an identical adjoining property, the kitchen sharing the middle wall) and their kitchen is absolutely fine. They had theirs upgraded at the same time (in 1982) and haven't redone it since and the floor is perfect and the walls have absolutely no cracks. The neighbour said that the builders the owner of our house used were very shoddy and that he was meant to use them but threw them off the job. He was convinced that they'd used a dodgy mix when redoing the floor (i wonder if they filled it with stuff they shouldn't) and that's why it's collapsing.

Obviously either way we're going to get a full structural survey but I would really like to get a detailed idea of exactly what is wrong with it and whether it's just a dodgy floor or serious structural problems. I wanted to check what the best way of getting this done is, obviously the structural survey will give us an indication but i'd really like a more concrete understanding of exactly what's wrong (and ideally what we need to do to fix it). If anyone can suggest anything (or knows any surveyors in this area that specialise in this type of thing) then it would be greatly appreciated.

Thanks very much!

Dave

 

[Nige F]

you`re right about the fill under the floor Inappropriate material and not rammed down enough , probably . I`ve seen a whole floor drop 4 inches , level all round , just dropped because the builder used chalk He also dropped a bo-lok on a low pitched roof , it was cut and pitched with the members bolted through - after 20 years it spread a tad @ one end and cracked a bit of brickwork . How do I know this - cuz I lived in the house with the roof issue the floor was in a bungalow in the same development , and I had to retro fit a cavity tray for another bungalow owner . BUT the builder was not a bad guy - he was a M8 of my dad`s - even the good guys can make mistakes . PLUS I`ve seen a lot more lash up`s and " latent defects" in social housing that was thrown up in the 80`s - kept me in work and paid the 15% mortgage for half the 80`s . Dave - the only way you`ll find out what`s been done to the floor is dig a hole in it . But the good thing is if you have it re done from scratch you`ll end up with a much better insulated floor . Good Luck

 

[deshg]

you`re right about the fill under the floor Inappropriate material and not rammed down enough , probably . I`ve seen a whole floor drop 4 inches , level all round , just dropped because the builder used chalk He also dropped a bo-lok on a low pitched roof , it was cut and pitched with the members bolted through - after 20 years it spread a tad @ one end and cracked a bit of brickwork . How do I know this - cuz I lived in the house with the roof issue the floor was in a bungalow in the same development , and I had to retro fit a cavity tray for another bungalow owner . BUT the builder was not a bad guy - he was a M8 of my dad`s - even the good guys can make mistakes . PLUS I`ve seen a lot more lash up`s and " latent defects" in social housing that was thrown up in the 80`s - kept me in work and paid the 15% mortgage for half the 80`s . Dave - the only way you`ll find out what`s been done to the floor is dig a hole in it . But the good thing is if you have it re done from scratch you`ll end up with a much better insulated floor . Good Luck

Hi Nige, thanks so much for your reply that is what i was hoping to hear As you say it would appear all we can do to find out is to dig a hole in the floor, which the vendor might not be too keen on. Would we get away with drilling some boreholes to establish what's under there or are you likely to have to dig out a significant part of the floor to find out? And are there surveyors who would do this kind of thing specifically so we can establish the cause, i'd rather this than go to an underpining company or builders as they have a vested interest in what work needs to be done (and i want as much certainty as possible)?

Thanks so much for your help,

Dave

 

[joe-90]

Give us a photo.

 

[^woody^]

Most probably, its compaction of the fill beneath the floor. If so its not really a major structural problem, more awkward than anything.

However, some of these properties may have a timber floor (or have replaced timber floor with concrete) and some can have (or had) a part- basement like room between the annex and the main house - which may have been a larder or coal store.

I doubt if you will be permitted to do any destructive tests, but the problem should be fairly obvious to deduce by someone experienced.

Normally you would allow for floor replacement and reduce your offer accordingly

If you instruct someone, ask them to comment on costs as well as remedial work. Also, ensure that if you use a building surveyor, then he will comment on structural matters and remedial work, as many will just recommend a further survey by a structural engineer .... so it may be worth just instructing a structural engineer in the first place