Ballpark estimate for small ground floor extension

Leaseholder49

Is there anyway to get a ballpark estimate for the cost of a small extension without having a builder look at it in person? The scope would be a single story 'infill' of the gap across the back of the house between kitchen and property boundary to create a downstairs toilet/utility, area approx 5sqm. The access would be through an existing door from house to garden, no changes to kitchen. Small town in West Midlands.

It's a very common extension on this type of 1900s terrace but I don't know any builders who I could ask informally, nor anyone who lives in such a house who's had an extension done. 

I'm not at offer stage yet so can't ask anyone to go and look, but I'm trying to guage whether houses with the extension in place are better value at ~40k more than one that needs the work doing (work which I might well not bother with myself but would probably be of interest to future buyers).

Thanks!

BonaDea

Around £2000 per square metre.

Albermarle

BonaDea said:

Around £2000 per square metre.

So a brick built extension, with a solid roof, with plumbing, drainage and electrics for £10k ???

FreeBear

BonaDea said:

Around £2000 per square metre.

More likely £5K per square metre. Small projects are usually more expensive than large ones on a square metre basis.

Leaseholder49

Thanks - in this specific case there would only be 1 new wall being built (along the ~2m end) as the other 3 sides are already walled.

In any case, it sounds as if it wouldn't be a hugely cost-effective solution considering prices of houses with the work already done, and the potential hassle involved.

FreeBear

Leaseholder49 said:

Thanks - in this specific case there would only be 1 new wall being built (along the ~2m end) as the other 3 sides are already walled.

In any case, it sounds as if it wouldn't be a hugely cost-effective solution considering prices of houses with the work already done, and the potential hassle involved.

One wall plus a roof shouldn't be hugely expensive, but.... Consent from the neigbour might be an issue, and a party wall agreement could get expensive to service. On top of that, if the foundations for either existing walls are not deep enough, underpinning may be required (more money). You also need to consider where the drains are and consign yourself to having to move some/all of them (more digging, more money).