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Extensions

Pricing single story rear & 2 story side extension

Anonymous user 09/03/2024 - 3.00 PM

Hi. Any help here would be very much appreciated. I’m trying to get an idea of how much the following would set me back. I am looking to carry out an extension on a standard semi-detached just outside of London. Ideally what I would love to do is build a single floor open plan rear extension approx 20m2, and a 2 story side extension of footprint approx 18m2 (This would also include extending out the existing roof). What I would be looking for is just the shell. Eg. Walls and roof, plumbing, electrics, plastering & windows. But with exception to these I would do everything else myself. I’ve seen prices about £1500 per m2 and slightly less for a 2 story extension mentioned online but I’m struggling to really get a grip around how much less just having the basic shell built would be. Appreciate it would be impossible to give an exact number but if anyone has any ideas/experience how much this would cost then would be great if you could share. Building regs should be fine by the way. Quite a few down the street have done similar or even larger extensions. Thanks!

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2 Answers

D&E Designs

Rating: 5 out of 5

Ormskirk

Building Regs and Planning and separate and both would apply in your instance. For London £1500/m2 is probably on the cheap side and more likely closer to £1800/m2 for the single storey. For the two storey you're probably looking at £1300/m2 (combine ground floor and first floor area) You mention extending out the loft,I'm not sure if you mean just a standard loft for storage or a loft conversion if it's a conversion you'd be adding more to the cost again.

Answered1 February 2019

Anonymous user

Yes £1500 per square meter is usually the going rate in south west. However London and outskirts could be considerably more. As just a rough guide I would expect you would still be paying for £1000 - £1200 per meter squared for the shell to be built as most of the money on extensions is swallowed up in ground prep and foundational works up to damp course. Would be a bit cheaper if you are going to be using suspended floors rather than solid concrete and screed floor.

Answered1 February 2019