The rough rule of thumb is that the basement space is worth roughly 60% of the above ground space.

I’m not sure what Herne Hill house prices are at the moment, but I’ve had a quick look on Rightmove let’s assume £1.3-1.5m for a 2,000sq ft house, which is £750/sq ft at the top end of the range

The basement space will be therefore be worth around £450/sq foot
so a typical 650sq ft basement (about the footprint of the ground floor, less stairs, corridors etc), you’ll be adding just under £300k to the value of your house.

And as the previous poster said, you will be looking at around £500k to get the work done.
So you’re losing £200k, plus whatever additional costs if you move out

It would be far, far cheaper to move house, even once stamp duty goes back up.

Unless you’ve got an exceptionally unique house (and it doesn’t sound from your description of it as a Victorian mid-terrace that it is?) there is no economic point in doing the basement.

The reason basements are popular in other areas is because it’s a cheaper way to add space than moving to the next size up house, but when you’re house is worth under £1,000 sq/ft, it’s almost always cheaper to move

Agree with the previous post. A basement was something we were considering a few years ago - my husband was a proponent.

We had a couple of quotes including Estbury (who were great) they came out around 500k to get second fix in the basement which would go under the full house around 60 sq metres. We lived in the Hyde Farm Estate in Balham there was no precedent on our street. Unless we were to live there for ever I felt we would never get our money back (value of house + basement) and was afraid it would be a white elephant - why would the kids play downstairs when they could be above ground? Would I really want to be going down to referee on arguments etc etc?

A good company like Estbury should help with the planning phase including planning permission. Why go to this expense and stir up local hatred until you know you will go ahead.

We visited some similar houses with basements and eventually decided moving would be the best thing. We managed to upgrade to a larger detached house a couple of streets away renovate and extend to exactly how we wanted it. All in all we had change to spare compared to if we had stayed put and dug a basement!

You live in while you dig a basement but despite all the efforts to seal off the work, it will be noisy and dirty. If you can possibly afford it, move out. For most builders, it will be cheaper and quicker to get access from your ground floor

In terms of companies, most of the branded design and build firms will sub contract the work. One or two like Estbury will have their own teams and probably get some economies of scale doing that. Despite the apparent complexity of a basement dig, it’s actually a fairly straight forward job to quote for which is why most price it up on a £/sq metre basis. The only real surprises will come with where the water table is (will you need a temporary pump during the dig. And are there any drains to move.

Go for high ceiling heights (2.7m minimum). With the standard northcote road terraces there is a tipping point where too high makes it look like a corridor

Bear in mind the quality of the fit out has a huge bearing on the cost, but also how much value you add. A well located stair case, good quality integrated lighting and nice rooms you actually want to use will make it more desirable to a buyer . There are a lot of basements round here which don’t get the use they were expected too

Finally be realistic about how long it will take. Probably a year start to finish. Your neighbours - with some justification- may hate you for a while. Often moving is the simpler choice.

Hi Dan,

Silly question but have you already had some quotes, and also spoken to an estate agent to get an idea of the post-basement house?

We stupidly went through the cost and hassle of getting planning (including having one of our neighbours start a street petition to get people to object to our application on the basis that they were worried it would cause the terrace to fall down, so that’s been fun...)

It was only after we got awarded planning that we compared the cost vs the new valuation and found... we were adding less value than it was going to cost to do the work.

So we moved instead

That said, we had several people recommend Estbury, who use a technique which means you don’t need to move out.
Other companies are cheaper but leave so much of the house out of action that it makes it very difficult to stay in the house during the main part of the work

Hi, 

We're just about to apply for planning permission for a basement conversion (late-Victorian terrace in Herne Hill/Loughborough Junction in Lambeth) and would be grateful for any advice on:

- recommendations for people to use - shell/core, structural engineers, party wall surveyors, fit out, etc (both good and bad feedback is helpful);

- whether you moved out (or would recommend it) - and, if so, for how long;

- general tips, tricks, advice and ideas (including on how to keep the neighbours happy!) - basically anything you think might be helpful.

I'm having a trawl through the site here generally (and elsewhere) for this too, and there's some great advice already (so no need to repeat yourself if you've said something recently on this). I guess one of the concerns is finding good builders (rather than those that regularly dissolve and re-form their companies to avoid liability/claims issues, etc, as quite a few do) at a sensible price. There's also quite a few "reviews" that appear to be self-promotion/from connected parties, so it can be challenging to filter out the noise from the genuine feedback. 

Many thanks in advance. 

Best, 

Dan