SE London extension cost

[Lilyrenovations]

Hi all,

I've just had an offer accepted on a house in South East London, or more specifically Welling.

Can anyone tell me how much I should expect a 2.5m*9m (22.5sqm) single story side extension to cost near the area? Ideally this would create a single bedroom and a small bathroom.

Additional questions if I may:

• How much will the cost increase be if I were to opt for a 2 story extension?
• Does anyone know if the single story side extension would fall under permitted development?

Thank you in advance!

Following with interest.

Op is yours a proper side extension or a side return?

Might be a stupid question... but what's the difference between a side extension and a side return extension?

Other houses on the same street has an attached garage on the side of the house but the one I am purchasing doesn't. I'm effectively looking to build where the garage would usually be, except to use the space for a bedroom and a shower.

Are you looking to do an extension nearby as well?

I presume you just need a doorway cut through to the extension from the house, and not a giant steel to support that entire side of the house? That will help with pricing, compared to e.g. a side return extension with lots of glazing. Any drainage on that side of the house that would need re-rerouting?

Builders are in high demand and materials prices are off the charts. I’d take a rough guess at £70-£90k, depending on the standard of fit out.

Would it not be cheaper to buy a house that already has an extra bedroom? Likewise a loft conversion may be cheaper.

Yours is a side extension then. A side return is the little narrow bit that runs to the side of Victorian terraced/semi detached houses. You can’t usually make them into a whole room on their own as they’re so narrow but they can make a nice big kitchen diner. Like PP said the cost implications are different.

I’ve just moved into my house and am wondering if we have enough to do our side return. I suspect the answer is no - we have £140k for renovation and that would have to account for everything including fitting a new kitchen. Think I’m just going to have to reconfigure the internal space that we have instead. Keen to hear people’s experiences! Our extension would be 1.9x8m and the whole affected area would be 5.9x8m (existing plus new areas).

Here’s a lovely side return extension for info and for drooling over 🙂

We live about 5 miles away from you. We've just had a kitchen extension and the prices at the moment are off the scale. Builders are in high demand and charging accordingly. Building materials have risen sharply in cost. Ours has cost over £125,000.

@LeavesOffTheCactus wow, isn't £140K enough for the side return you want? But the pic you attached does look amazing and will probably cost an arm and a leg!

@MyAnacondaMight @SummerSeaSwimmer I am gobsmacked by these numbers. I was thinking 2k per sqm! Do you guys know how much a loft conversion would roughly be?
The good thing is that this house needs no work, albeit a bit small. Was planning to extend out to get a bigger 3rd bedroom and use the existing box room as a study... maybe I need to rethink!

[quote Lilyrenovations]@LeavesOffTheCactus wow, isn't £140K enough for the side return you want? But the pic you attached does look amazing and will probably cost an arm and a leg!

@MyAnacondaMight @SummerSeaSwimmer I am gobsmacked by these numbers. I was thinking 2k per sqm! Do you guys know how much a loft conversion would roughly be?
The good thing is that this house needs no work, albeit a bit small. Was planning to extend out to get a bigger 3rd bedroom and use the existing box room as a study... maybe I need to rethink![/quote]
We had a loft conversion about 10 years ago, I think prices have risen so much in the last year or so that there would be no comparison to costs nowadays. But it was so much easier than the ground floor extension we've just had done, so much simpler and more straightforward.

We're looking at £60-£80k for a loft conversion in SW London.

It varies. We are doing something similar in S London and it's about £70k, though we did get quotes up to £100k. Our garden slopes upwards so we've had to pay an extra £15k to dig out and build a new retaining wall. Things like moving drains, putting in steel beams, etc can add to the cost.

Permitted development rules depend on lots of things, like your overall plot size, how the extension will look from the road, etc. There are some details here: ecab.planningportal.co.uk/uploads/miniguides/extensions/extensions.pdf

Builders are in high demand at the moment so if you can wait, I expect prices will drop. It's probably also worth living in the house for a year or so to see how it flows, where the light comes in, and how the space works for you.

You've picked the absolute worst time to do work such as this. Give it a few years, when builders will be looking for work and materials costs will have returned to normality. To say you might pay half your current quotes isn't an exaggeration.

Thanks all for your input, this is hugely appreciated.
I've gathered that I should get saving instead of dreaming about extensions! All the builders must be rich...

I have just priced a similar side extension with glass roof etc in west london , worked out at £2.5k a square metre plus some remedial work

No parking outside and access through the house pushed this up by £500 square metre

If things calm down in a year or so, you might hope to pay a bit less - but still probably £55-70k. If it’s a 1930s type layout then you could probably get a bedroom and bathroom in the loft for £10-15k less than the extension version, and still keep your off street parking.

I find £/sqm totally unreliable in terms of pricing a job. Once you have a price, it’s a useful reference point in terms of checking whether your build is likely to pay off in terms of adding value - but you can’t price a job based on size. The biggest price drivers tend to be groundworks and drainage issues, access, glazing, and structural demands. These can make a tricky 10sqm extension cost more than a basic 20sqm.

About £2000/m2 for a shell. Then factor in electrics, plumbing, plastering, flooring, heating, decorating etc. It costs about 50% more for it to be two storey.
As for the PD you'll have to check with the borough, but I believe usually no if it's to the side and can be seen from the front.

OP we’ve had our first quote back! Big company that’s got a really good reputation so that will add cost (eg VAT).

Extension including electrics and plumbing, 4m bifold doors and glazed roof but excluding kitchen fitting and decorating etc = £65-70k plus VAT.

Lots of other cost estimates came back too.

Decorating per room: £900 + vat
Moving manhole: £2k + vat
Tiling and floor laying: £40 per m2 + vat
Kitchen fitting: 3k + vat
Building inspection: £900 + vat
Asbestos survey: £300+ vat
Making good the garden not included and not quoted

The reason that building costs are so high are the rise of cost of materials (combination of covid and Brexit) and a change in the labour market. A few years ago huge amounts of labour in London was provided by eastern Europeans who were highly skilled in the trades. They were cheap and excellent. This source of labour has reduced significantly (again partly covid and partly Brexit). Now you are paying local builders who have living costs similar to yours and therefore charge you more. They aren't rich.
None of these issues will change in the next few years.
I wouldn't hold off life plans thinking things will get cheaper, it's just not going to happen.
I would budget around 80k for the work OP has described as there will always be knock on issues in the existing house that will then need dealing with.

Thanks all for your extremely helpful input!

@LeavesOffTheCactus which company is this, if you don't mind sharing?

I think my best bet is to get some builders in to quote once the purchase is complete and see where I can go from there. House is in ok condition so might worth me saving up for a couple more years.

We are in the south London/Surrey border area. We've just been quoted 35k plus vat for a 10m utility room extension. Ouch. We are waiting for other quotes and hoping they will be a bit more reasonable.

@Hothammock they're not all rich but most builders do alright!

@Lilyrenovations they’re called north london lofts - I’m sure they work in south london too (and they don’t just do lofts)

@SD25 probably because they aren't squandering all their wages on renovations and extensions like the rest of us