First time extension

[Jellybabies123]

Just looking for a bit of advice, we are looking at doing a ground floor extension. We've had a look online but we just don't know where to even start! We are looking at going out approx 5m, width approx 8m. If anyone know roughly how much we would be looking at cost wise to get it watertight that would be amazing as well. Thanks

Our builder said £1200 per sq m (+VAT) for a standard build, £1500 per sq m for us as we need Cotswold stone. Plus £500 per velux and £5000 for bifolds. We used that as a guideline x

Thanks so much. Thats really helpful!

Seems cost of building is more like £3k+/sqm in London.

We the adding approx 60sqm and our quote is approx £280k (including a fair bit of internal remodelling).

Do you know you can go out that far? You'll need planning permission I think (rather than it coming within permitted development). We've just had a double storey extension (usually slightly cheaper than single storey extension), not London, and it was roughly £2k per sqm, plus VAT to a plastered finish (kitchen / bathrooms / doors etc on top)

We've had plans drawn up for a 6m x 3m extension, and are just waiting for planning permission atm. I'm waiting for a quotation from one builder, and am planning to email some more this weekend, so I'll update when I hear. We have had an unsolicited flyer in the post (because off the planning I assume) offering £1500 per sq m. But round here at the moment (south east not London) decent builders are booked up at least 6 months in advance, so I won't be going with someone who's having to cold call for business.

Be aware that the price to first fix (a watertight shell with the basics of plumbing and electrics in) is considerably lower than the price to second fix (fully done). Finishes are more expensive than you think - even if you don't have expensive tastes.

Budget for an architect, structural engineer, planning, building regs in addition to the actual build too.

You may be able to go for permitted development (depending where the property is for example England or Wales) but under neighbour counsultation scheme they call it, by submitting householder’s prior approval notification for a larger dwelling or to that effect (can’t recall the exact wording) BUT it depends as well on other conditions/limits that the proposed extension and the existing site scenario/layout have to satisfy. You should set aside budget for an architect, structural engineer, planning application cost, building regs cost, etc too.

Yep I would think £1200-£1500 per square metre for watertight would be about right, depending on where you are. Good luck

Thank you all so much its so helpful. We have looked it up and it falls under permitted development until 2019. So need to get the ball rolling as it were. Now to try and find an architect to draw up some plans!

@Jellybabies123m , well I’m one, registered with ARB, just started my own architect’s practice now (so I’m quite cheap), though I’ve been doing it for larger practices for the last 15 years. The last three years I’ve been designing/drawing up lots of rear extensions & planning applications for houses including permitted developents, so sounds pretty much like what you want to do.