House extension

[kkgirl]

Nothing much to do with chidren, except that they take up loads of space.
We are thinking of building an extension on the back of our house, full width and about 8-10 deep.
I can imagine how it would work with the roof really, but we are thinking double storey would be good, but have no idea about cost and don't really want to start the idea off if it wouldn't work.
Has anybody had any experience of extending their house at all who could give some general advice on this.

I would plan on minimum around £60,000 and with fancy finishes you can easily get into the 100's. You will probably need planning permission and i would recommend hiring an architect (though i am an architect, so i'm a bit biased).

I used to go out with a builder and I typed up his quotes. I think that house extensions worked out roughly as £1,000 per square metre. This was actually some years ago and probably now out of date but may give you some idea.
Also, he always advised friends never to go for the cheapest quote because the chances are that "extras" would be added on once the job was underway.
Hope this helps.

I had a demolish and rebuild of the rear third of my (small terrace) house done whilst pregnant. This is in Cambridge, so prices may be cheaper than where you are, KKGirl. Basically we had 48 sq m built (on two floors ie 24 sq m per floor) with a total cost of about 43k including finishes, new kitchen and new bathroom. So £1000 per sq m probably not a bad rule of thumb for here (although this was 18 months ago).

The big difference with having a second storey (I think) is the footings you need to put in. Mind you the planners round here insist on pretty substantial foundations even for a single storey extension, on the grounds that a second floor may be put in it later.

Try talking to an architect for some idea of how the process could work and costs. You may find your job is too small to hire one as a project manager, but it's worth thinking about.

Oh and don't do what I did and forget to budget for contingencies! Basically, if you can't afford to add at least 10% contingency to the job, then don't do it.

HTH

Thanks for your help on this one.
Just to expand a bit, do you draw out your rough plan and then ask the architect to look at it, or do you tell them your ideas and then they draw it up. I feel a bit of an idiot but we have never had any building work done on any of our houses.
I'm not sure how we could have a full width double storey how it work with the roof, could they change the roof or would it have to be a complete reroofing

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kkgirl, the architect will draw up the plans for you. You just take them around and show them kind of what you want and they will suggest ways to do it. It's important that you make clear to the architect what kind of things are important to you because not everyone has the same priorities in a house and there is no single right way to do it. As robinw said, it is important to make sure that the architect is really an architect. A registered architect is required to carry insurance and deal with disputes in a specific manner. If something goes wrong then you will be covered. It is illegal for someone to represent themselves as an architect if they are not registered. There are lots of draughtsmen out there who can draw up adequate plans, but who are not actually architects. This could be ok if you have a good builder and know what you are getting in to and it could save you some money. But it does mean that you have no recourse if the plans are not correct. Also a proper architect will do more than just plans. They will do a specification that tells the builder the correct way to build it and the right materials to use. You are more likely to get things that work properly that way. A proper architect will charge somewhere between 10 - 15% of the construction costs. Ask around to your friends and neighbors whether they have an architect they can recommend. Are you in London? If so I might be able to make some recommendations.

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robinw, I agree, architects do get things wrong too, but things like showing the client all the tenders would be something that a "real" architect would be required to do. You unfortunately ended up with someone who was pretending to be a licensed architect but who wasn't and therefore wasn't sticking to required procedures (and also probably wasn't fully trained). A registered architect could lose his license for not following the "rules" and the RIBA is quite strict about following up complaints.

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