House extension

[canary19]

HI all, thinking of making an offer on this house - does anyone know how much it would roughly cost and how long it would take to square this house off with a side extension at the back - it would be and downstairs and upstairs extension. Many thanks x

£2000 per cubic m. Depending on location, problems encountered, cost of materials and finishes. It’s about what you want it to look like really. Cheap as chips or a well finished job that matches the existing bricks etc. Don’t forget the garden and how it will work with the existing rooms. There is an additional cost of internal walls are altered.

I'm confused about the cost when people state 2000 per square meter. Is that for ground space or up and down? So for a 10 sqm ground space, double story, would it be £20000 or £40000?

Depends entirely where you live ... I'd say about £25-40 depending on area and finish .. also you may need a new kitchen which could be any price from £3k upwards .

Definitely tens of thousands, price per square metre is most reliable for a simple box.
We did an extension to match in with the existing house which involved restructuring the roof, and lots of steel, neither of those added any square metres but they were important to us.
I think in the end it worked out over 4k per square metre excluding electrics and plumbing, kitchen, and all the internal finishes. Also windows were additional.
We also paid around 10k of non builder things eg professional services and permissions/legalities.

You could use this: www.homebuilding.co.uk/extension-cost-calculator/#help

I found it very useful.

And if it's a 2 storey build then 10m2 ground floor is 20m2. But the price for the top floor is usually cheaper than the ground as that's where the expensive groundwork is needed.

You also need to add planning fees and maybe an architect fees.

Hope that helps.

Wouldn't that make an internal room with no window though? How would the layout work, particularly upstairs? Also need to look outside and see if there are any drains in the bit you want to build over.

THanks for your help everyone - does anyone know how long it would take roughly? OliviaBenson - I'd make the smaller room the bathroom upstairs so that wouldn't have a window but downstairs would have the whole back wall with window-doors to add light through the bottom I think. x

Ok but moving a bathroom you need to think about plumbing and where it will drain. It will cost more to do that too...

If it is not a detached house, you might not be allowed to do a two story extension?
Is there not a rule regarding habitable room windows??? I might be wrong though.

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