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2 Storey home extension and cost estimate advice needed

Posted: Fri Nov 06, 2020 5:00 pm
by dinoman
Hi all,

We are buying an old existing 3bed semi-detached house with the plan to extend it. In a nutshell it will be a 2 storey extension where the ground floor will see the existing kitchen extended, new shower room downstairs and study room. On the upper floor there will be new family bathroom, ensuite, bedroom extension and an additional bedroom at the rear added. Total new extension part approx 90metre.sq.

Before we even start we wanted to grasp more accurately how much this project will cost us.
We've been told there is a good rule of thumb being a cost per metre/sq we can apply. Which is ground floor £1500/metre.sq and first floor £750metre.sq.

But we have no idea what this does or does not includes. We don't want to proceed on this basis assuming everything is included as that would be risky to our budget.

We was wondering whether this would be include: windows/doors? All drainage / Insulation / Roofing to new part of extension?/ Internal plastering and decorating? electrics / plumbing? Flooring?
Does anyone here know what this might be included or not? Or any other better rules of thumb we can apply?

We have so far only allowed separate cost for Architect/structural engineer fees / Kitchen fit out and some loose furniture.

Any advise from people with experience would be much appreciated!!
Thanks.

Re: 2 Storey home extension and cost estimate advice needed

Posted: Fri Nov 06, 2020 10:52 pm
by stoneyboy
Hi dinoman
Since you are having bathrooms on both levels suggest you double your sq m guide costs on both levels, if you are in the London area this may be 3x.
Regards S