How much for extension of this type?

[Equimum]

We currently have a large conservatory across the back of our house. It measures roughly 2.3m x 5.5m and has brick up to thigh height, then UPBC glass panels. Next to this, there’s a small brick build structure of about 2x1.5m.

Ideally, we would like to take all of this down, and build one 7x2.8m extension, which would become a kitchen-diner. We would still need lots of glass as this room brings light into the rooms if attaches to. Without the kitchen etc, but with electrics, plumbing etc, what would you expect to pay for the demolition and reconstruction (SE)?

We’ve had one rough estimate of £100k, which seems very high to us, but we’ve never done anything similar before so can’t be sure. I don’t want to waste lots of tradespeople’s time if this is what it would cost, so just interested in what other’s have paid for similar, so we can gauge if we are being unrealistic.

Usually basic finish, so walls, plastering, floor etc is £1500 (plus VAT) per square metre and high end finish with underfloor heating and lots of glass etc around £2500 plus VAT per square metre. That's what our architect told us three years ago.

We did a ground floor extension about 9m by 6m over two years ago. Our overall cost, minus kitchen, just under £200 000. We had a large space and many high end finishes in the floor/light switches etc so obviously this was our choice and you could choose less expensive things. This is SE London.

Unfortunately £100 000 doesn't sound too far off for me.

We are currently doing a 2 storey extension with a lot of glass measuring 8m x 4m. It is 110k excluding the kitchen and flooring.

We had quotes for a similar size extension (slightly smaller actually) £100k without finish - so no kitchen etc. Total cost was looking at above £150 for a good finish. So we decided not to do it!

Thanks Auntimmortale, that’s a really useful guide. On those calculations, a mid-range finish works out to around £50k (obviously, excluding demolition and fixtures and fittings). We had hoped to get the whole lot down for around £100k. There is no knock-through or anything, as we want to keep the existing entrance, and we were planning on around £25k for the kitchen.

I might look into how feasible doing some of the demolition ourselves would be.

We are paying 1800 (including vat) per square metre to a plastered finish (including electrics) and includes roof lantern, windows, door and bifold doors. Does not include kitchen or flooring

Thanks Hisashiburi. Do you mind me asking which region you are in, please?

I'm in NI and that seems quite high to me but maybe a regional thing.

Hi, ours was to a plastered finish, full-length bifolds on both external walls and a latern (smaller than we'd like) was £2500+ vat per square metre. No electrics as that was part of a bigger job. No underfloor heating. South.

Thanks.

Mytimetogo we were told it would cost substantially more than quoted if we wanted bifold doors, so it’s interesting that you got them included in that price. Thanks.

I will have a call round tomorrow and get some more quotes.

Fully finished you should get that under 100k even with a 20k kitchen

And that should get you bifold and any other high end finish

I'd guess 65-85k based on what others have paid near me. Maybe I'm unrealistic

Oh plus 20k kitchen, not far off then

Hi. This is in the South East

We had similar except it included a side extension of 4x3 (so plus at the back 3x 8). Approx sizes only btw.

For the build including fitting the kitchen and flooring we paid £50k. Adding everything else we had done including the cost of kitchen plus appliances, utility room cupboards, the garden turfed and patio laid, toilet fixings, had some minor bits done indoors, meters moved, cost about 95K total. Nothing there to start with to knock down.

So get more quotes. Greater London here.

Ask them just to price on the build and you supply (they fit) all the 'finish' items, floorings, kitchen, doors etc then you have total control and it's not left to the builder to have their own special interpretation of the level of finish you asked for.
Build I'd guess at 50-60. Plus demo and waste removal, plus whatever finish you want... I'd consider sliding doors over bi-folds.

100k sounds quite a lot for basically an oblong box with no e.g., extra bathrooms added.

Fully finished with a kitchen maybe, but it's only 20m2 of additional floor space. Think of whether that will take you over the ceiling price for the area.

And yes agree sliding doors are fine - unless you want it to run the whole 7 m length or something. I've never seen the appeal of bifolds really. It's not like you need a 5m aperture to exit/ enter, and visually there is still a lot of frame obscuring your vision. They are also excellent for trapping your fingers in.