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Bromley - Rear extension 5m X 3m cost

(23 Posts)
321pastamaker Mon 04-Nov-19 06:18:39

What is a realistic expectation? This is to knock down a conservatory, replace with a 5m X 3m extension, getting rid of an internal wall to make the space open plan. Ideally creating a utility space and downstairs toilet. We would then need to fit a new kitchen. Is 70-80k doable?

donquixotedelamancha Mon 04-Nov-19 06:58:06

Is 70-80k doable?

One floor? I should think easily. We went out 4m by 7m, new kitchen, new toilet and utility, open plan (so big steels), karndean floor, quite a bit of wiring and plumbing changes, extra insulation, expensive windows and doors. 55k for everything.

Not in the south, but can't imagine 70k won't cover it unless you make some very expensive decisions.

Alexalee Mon 04-Nov-19 07:31:48

Yes with a kitchen costing under 20k it should be doable

CatUnderTheStairs Mon 04-Nov-19 07:33:36

We were quoted 40k for something similar but not fitted out in an expensive area. If it’s not permitted development you’ll have to think about plans being drawn up, structural engineer etc.

321pastamaker Tue 05-Nov-19 16:39:37

Thank you, that is helpful. I wonder how significant the "South East/London" effect is, we won't be choosing the most expensive options - far from it!

Alexalee Tue 05-Nov-19 17:03:28

If you dont go for top end or crazy fittings then you should be aiming for under 50k

321pastamaker Tue 05-Nov-19 18:08:42

@Alexalee - that is my thought, just need to find a like minded builder!

minniemooblue Tue 05-Nov-19 22:32:26

We are south east. Planning a single storey kitchen extension with internal remodelling to include a utility room with shower/toilet. Our plans have gone out to tender to 3 builders and we should hear back my Friday.
We did have one builder come round and quote £72000. This didn't include the final structural beam information, flooring or kitchen. So would have been £90000++ I think.
We are hoping to come in below £80000 for everything! I will let you know when we have heard from the builders.
I will try and attach a floor plan of new extension.

SurveyorScott Wed 06-Nov-19 08:42:28

A good guide for building costs for the SE is £2200 per square metre plus VAT. Economies of scale do come in to it, so a really small project will cost more and a large extension will cost less per metre.
Usually that includes everything to a basic plaster finish, electrics and heating - things like kitchens, demolition and large knockthroughs would cost extra.
So a 5x3m extension would be approx. 5 x 3 x 2200 = £ 33 000 plus VAT.
Hope that helps!

Getitdonet Tue 12-Nov-19 05:06:09

Resently did renovations in same area & what i did is more than what you are having done. I would say your budget is good, on the assumption build cost is circa 60k or under inclusive of plastering, beams. depending on your finishes & what appliances you may need to have & being savy will determin if you can source things for the remainder. I would also budget £5k contingencies for fees- for PW if required & structural engineer & tiny misc...
Be clear what the build cost entails right down to skips so you minimise any suprising additional cost u thought was included . All the best.

TheBlessedCheesemaker Tue 12-Nov-19 05:16:44

Just finished doing exactly this in Kent. Came in at around £70k, That included a set of bifold doors, velux roof lights, shower room and new kitchen. Competent builder/s and very good quality (but slow to finish off as did the usual thing and started next job before he should have).

SurveyorScott Tue 12-Nov-19 08:39:29

Some wildly varying prices here, all I can say is get at least three quotes from reputable builders. Ask your friends if they can recommend anyone.

The basic price can be quite reasonable but it can sky rocket when bi-folds, internal rearrangements and expensive kitchens get added on.

bengalcat Tue 12-Nov-19 08:45:42

Ah this thread is really helpful . We are in a ground floor flat in west London and would like to extend out to have more floor space and go open plan .

donquixotedelamancha Tue 12-Nov-19 12:29:06

Some wildly varying prices here

Our builder quotes for the extension mentioned above varied from 40k to £60k. Our kitchen costs varied from £8k to £21k fitted, for the same (highish spec) kitchen. Our floor will be £3k sourced online, but quotes from shops range from £4-5.5k

We still wasted money on a structural engineer and drain survey we didn't need.

The easiest way to save money is to spend a very long time planning every detail and to draw out (and be sure) before you go to an architect.

Pull up carpets and boards so you know which walls are structural, so the architect draws what actually needs to be built. If I had to do it again I would not use an architect (because he was shit and expensive) but that does add on faff and time.

Mummyshark2018 Tue 12-Nov-19 13:31:05

We recently extended which included:
Knocking down conservatory
Building a 6x6 extension for kitchen/ diner/ sofa area. Bifold doors and island kitchen
4 velux roof windows. We have a high pitched roof and two other new side windows
Remodelling downstairs which included putting up a few stud walls
New utility and shower room in old kitchen
New flooring and decoration (dh did some of this)
All came in around £70-75k.
We're in the south-east so I would say totally doable on your budget.

321pastamaker Tue 12-Nov-19 17:07:50

Interesting looking at the differences for what people seem to have got for that kind of budget. Definitely not looking for high spec/fancy materials, just a good job done well! @minniemooblue what was the variation between your quotes?

Smokk76 Fri 10-Jan-20 13:00:38

I specialise in single-storey extensions In South London, and my usual costs are as follows for 3*5.

- 42K simple shell including an opening 1st fix electrics plumbing and wood. ready for finishes (excluding bifolds, including Velux)
- 6K next room renovation (typically removing the wall between kitchen and dining and refurbishing it fully.
- 12K finishes including kitchen and understairs toilet (client supply finishes)
- 2.5K Underfloor heating
- 3k upgrading adjacent room floor to extension insulation standards
- 1-6K garden works
- 1-3K other possible costs depending on access and parking

Total usually is something between 55K and 85K.

Alexalee Fri 10-Jan-20 14:19:24

So cheap at nearly 3000 per m2 for a shell

Smokk76 Fri 10-Jan-20 16:15:00

@Alexalee I assume you are sarcastic wink

The smaller the extension, the more expensive. You can run m2 calc on 30-45sqm extensions bigger will be cheaper for sqm and lower more expensive. Just imagine 1x1m extension one sqm of the floor and roof but nine sqm of a wall. The bigger it gets you mostly add floor and ceiling.
So you can assume that once you build your first 15sqm, you will need only £1200 for every additional m2. and then with substantial extensions, the cost for every extra m2 may go down well below £900 for extra sqm

321pastamaker Fri 10-Jan-20 17:04:19

@Smokk76 Thank you for the info, this is helpful.

lightlypoached Tue 14-Jan-20 16:18:44

We are in sw london. Just finishing our 5x3 extension. Build cost £80k ex flooring, kitchen and decorating.

Gulp. It's fiendishly expensive in london.

SallyA2305 Wed 15-Jan-20 10:29:16

My friend recommended this website to help with a rough cost of an extension, really easy to use smile
www.loverenovate.co.uk/extension-cost-calculator
Hope this helps!

Alexalee Wed 15-Jan-20 13:48:09

For that price I will kick dh back out of retirement... more that double what he charged 10 years ago when he retired

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