[OT] rough guide to cost of extension?

[Dr Zoidberg]

This is pretty much directly opposed to on-topic as it involves getting builders in but I thought people here would be knowledgeable on such matters.

I'm idly considering an extension to my house and wondered if anyone has a rough idea how much it's likely to cost. I was thinking of a fairly lengthy 2 car long single width garage on the ground floor , then an extra bedroom above part of the garage on the first floor. That's probably about 8ft*30ft ground floor and 8ft*15ft first floor.

Obviously it's impossible to give anything like exact figures but it would be nice to have an idea of if I'm talking 10 , 20 , 30 , 40k etc

Yes I realise I could phone a couple of builders but in my experience they don't like to give even rough guesstimates on the phone and I don't want to waste their time getting them to visit as this isn't something I'd be getting done for a long while. Oh, and it's in the west midlands as that will obviously affect the price.

[The Wanderer]

A *very* long time since I did the same, and TBH, I really can't remember what the bottom line total was, all I would say is when you come up with a ball-park figure, double it and you won't be too far out from the final cost. :-(

As an aside, having lived through the experience once, I vowed I'd never do the same again. The aggravation and hassle just ain't worth it. I'd move every time to get more room.

[Dr Zoidberg]

Theoretically , what I have in mind shouldn't cause too much disruption or mess in the rest of the house as the extension would start behind the existing front door and the only access would be converting a window on the landing at the side of the house into a doorway to the new bedroom , but I do know how building works can find themselves taking a very different course to plans.

Moving house means a lot of "wasted" money in stamp duty , estate agent and solicitors fees and other costs and isn't exactly hassle free either.

Still , I take your point and when this comes to a serious choice rather than idle speculation I'd have to think long and hard about how much potential saving there is by extending Vs moving.

Another factor would be the difference in value of my house before and after extension compared to the cost.

I think in general a good extension adds more value than it costs , but I know that isn't always the case.

[.]

here's a gift to you and the other diy'ers who ought to know better.

get a copy of UK building costs blackbook from Franklin + Andrews

it's not THE bible but it's what quite a few tradespeople use to generate /estimates/ from.

estimates, mind. not quotes, but it will give you your ball park figure from which to gauge your opponents. it will also help you to think clearly about exactly what you want by way of building works.

hth

[OG]

I've heard the current figures are about £1000 - £1500 per square metre, the lower figure for basic rooms with electrics & plumbing - the upper for 'ready to live in' standards of finish. If you go for quality flooring and high standard fittings, you can be looking at £2000 per square metre and above.

I would estimate about 50 - 60k.

[dg]

Several of my clients have had quotes from =A340k to =A370k recently for the same job - two storey side extensions. These were from builders in the Birmingham area off the Quality Mark list or referred by the FMB.

A builder will need some plans and a specification to give you a meaningful estimate. And this will change if you don't intend to build in the short term. Specific foundations. roof construction design and structural alterations can have a big impact on any estimated price.

But your proposal is unlikely to be less than =A330k from 'proper' builders.

dg

[John Rumm]

I would guess that even with a flat roof you would be looking at the top end of your scale there as a minimum figure. With a nice pitched roof then you could easily run £60k+

You could however DIY for £20 - 25k I would have thought.

To get a decent idea it would help to have a set of plans drawn (may cost you £350) - may also cost as much again to get them submitted and approved by building control.

[Dr Zoidberg]

Pitched for the first floor bedroom and flat for the section of garage roof that would extend further back into the garden.

From what you and others have said , the average guesstimate could be 45-50k and I suspect that it would work out easier and a similar cost to simply move to a 4 bed house with garage.

Some of the work I'd be more than happy to do myselft , but I'm sensible enough to realise my limitations and wouldn't want to attempt the project entirely without professional assistance.

Proper plans are one thing that I would be happy to DIY - I may as well get some use out of a civil engineering degree :0)

[The Wanderer]

Doubtful

That's a specious argument put forward as individuals try to convince themselves of the merits of a particular course of action. Been there, done that, never made as much as I thought I would when I moved! :-)

What *really* affects the resale value of any property is the nominal value of all the other properties in the vicinity. If they're selling for £200k ± a little bit, you'll be lucky to realise more than a few £ks over the norm.