Advice on extension please

[bokkie]

Hi all. We are in the process of buying a new house and have fallen in love with one in particular, but would like to extend if possible.
It already has a side extension, which is bedroom 4/family room and the utility room. We have asked the vendor and they said that when they did the extension, they paid extra so that the foundations were ok to build another floor.
If this is correct, what would be a very rough price for building another floor making bedroom 2 a bit bigger, with an ensuite and another bedroom. would be somewhere in the region of 14 square meters.
From what I've read the rough cost here in the south east would be £1000 - £1500 per square metre is that correct, or would it be less as I already have the foundations?
Just a rough guess would be most helpful. I have attached a floorplan, Thanks for your time.
http://media.diynot.com/127000_126433_78751_45120292_thumb.jpg

 

[freddiemercurystwin]

Your cost estimate is about right.

 

[noseall]

It is unlikely to be any less because of the roof issues i.e. one will need removing and another building.
Logistically a second storey is harder to build than a ground floor building.
You may also have the headache of protecting from the weather what is currently within the ground floor structure like electrics etc.
An upstairs knock-through will also need factoring in.

 

[bokkie]

Thanks for your replies. so I should budget £15000 - £20000?
Would that be a good estimate? This would all be subject to planning permission of course.

 

[freddiemercurystwin]

That would be a rough estimate which is about as good as you'll get on here.