Rough cost of these extension plans? (London)

Doozergirl

itravelforchurros said:

Had a builder round yesterday and somehow he quoted a grand total of... £40,000!... for the finished ground floor rear extension of 36 sqm (Zone. 4). Pleasantly surprised/shocked...

Not a hope in hell.  We didn't even build our own house for that little per metre.   You will regret choosing them.  

It's been nearly 20 years since I first heard people batting the £1,000 a square metre price around and that was for a basic new build, without VAT.   He's not even quoting that.  He's deluded and you won't be pleasantly surprise if you give him the job.  

itravelforchurros

Doozergirl said:

itravelforchurros said:

Had a builder round yesterday and somehow he quoted a grand total of... £40,000!... for the finished ground floor rear extension of 36 sqm (Zone. 4). Pleasantly surprised/shocked...

Not a hope in hell.  We didn't even build our own house for that little per metre.   You will regret choosing them.  

It's been nearly 20 years since I first heard people batting the £1,000 a square metre price around and that was for a basic new build, without VAT.   He's not even quoting that.  He's deluded and you won't be pleasantly surprise if you give him the job.  

For context, it's a company (with fancy vans and stuff as opposed to a singular builder) and they're currently close to completing an identical house opposite ours with the same rear extension, which they let us view and it was great. What would be his incentive to grossly underquote here? 

ObserverOfLife

I was going to say that you will get what you pay for. 

He either did not plan out his cost estimate right and you will be left picking up a lot of hidden costs later that will end up costing more. 

Have you spoken to the neighbour directly and asked if the final total matched the original cost estimate and what it covered?

FaceHead

When it looks like a great deal, but you don't know why, it's a great deal, but not for you.

You know roughly what it should cost on a /msq basis. It will cost what it costs, and there is only so much wiggle room in the builders profit margin. 

Yes chat to the neighbour about what they paid, for what, and what extras came out of the woodwork. If there are any highly likely extras, try to agree them up front when you still have some bargaining power. 

 
Consider getting it professionally estimated so you know exactly what it should cost. 

You might as well get a written quote to try to figure out what's missing, but given there's something fishy/mistaken going on, it's best to steer clear.

GDB2222

Have you worked out how much the house will be worth after all the work is done?

As a rough rule of thumb, Zone 4 London property prices are something in the region of say £6k psm. So, adding living space at a cost of £3k psm ought to be highly effective. Of course, there’s a limit for the road, and there’s a limit to what people in the area can afford.