Rough idea of extension cost? Floorplan...

[LovesFood1987]

We're considering buying a house in the perfect location with a really good plot... From reading on here I understand we can't trust architect figures on costs. We're in the South East if that is relevant.

Not sure whether it would be stupid to only do downstairs in terms of resale value but for us 3 bedrooms is fine? So not sure if double or single story extension.

We'd have about £100K after buying the house.

(To be clear because of my terrible image, it's just a side extension and removing internal walls)

From our experience, given that you have a fair amount of structural work, I think £100k will not be enough. Looks more around the £150k plus decorating, new kitchen, etc could well be near the £200k mark.

Yes around £200k, maybe more in SE.

Our single storey extension (20m2) has come in at £68k plus vat. We have to supply roof lights and glazing (another £12 k plus).

We were working to a total renovation and small extension budget of £120k with the architect. It will be coming in at almost £95k more than that

In the SE by the coast, I’d say at least 150k but a lot will depend on cost and how much glazing you want/ the spec of things like floors, kitchens, windows etc.

Also on your plans, I’d definitely try to separate the new front bit off and make it into a study/ bed 4, if you’ve only got 3 beds upstairs. And are you getting rid of the separate utility- that would put me off, especially as there is no space to hang washing upstairs.

TBH I think with 100k I would open up the back of the house- so combine the family room and kitchen/ breakfast room with sliding doors to the dining room (but keep the dining room walls so it’s not so much structural work and it can be closed off to be a study/ bedroom if needed) and bigger doors across the back, keep the utility and concentrate on internal renovations. If you really want the side extension I’d do it at a later point. I’d also live in it for a bit before making any decisions ideally.

I also think if you’re worried about selling you’re correct that it might be odd for many buyers to have such a massive open ground floor (the back room would be enormous- i make it 30 foot by 19 foot which will be extortionate to heat) and then only 3 (reasonably modest) bedrooms and no en-suite upstairs. If you don’t have plans to extend the upstairs at a later point (like a loft etc), I’d definitely incorporate a space which could be used as a guest suite downstairs in any renovation you undertake. Otherwise you may well not make your money back (ask a few estate agents if you decide to proceed).

That is an enormous kitchen/diner which I think would look disproportionate to the house. Scale back a bit and keep the utility room.

And yes, north of £100k as is.

How big is the actual extension? Our single storey 11x5m extension with internal reconfiguration, including shower room and kitchen was £210K first part of last year. Were in the south west.

I would say knocking down all those walls and putting a new kitchen in, fully finished and decorated would cost you around the 100k with no extension
What you have drawn there will be 200k+ unforunately

I agree re disproportionate. Our rental's kitchen/diner lounge is the same size, if not slightly bigger, but on the same floor we also have a 15 x 15ft snug, 8 X 10 utility and 8 X 10 shower room. Upstairs X2 large bathrooms including one en suite, two bedrooms 15 x 15 and one 15 x 20 with a tiny dressing room. Each floor is exactly the same proportion of around 1200 sq ft.

I look at the floor plan and it feels like upstairs is really squished in comparison to downstairs.

How much garden will you be left with?

I often see people with fantastic extensions who have eaten up most of the garden and whilst that doesn't bother me (no kids) I nope right away from the advert because they are far harder to sell on.

I second pp on getting EA valuations before doing the work.

From what I read, doing big extensions never ever recoups the full amount spent, it will put you in the top of the pricing bracket for a house with that number of rooms. If you want to recoup building costs, I believe the best way to do that is to add another bedroom.

We are doing very similar and it’s close to 200k. Also in the south east.

Sorry I can see that there is an en suite upstairs but it looks a bit odd (does it have a loo) so my point about buyers who want a 29 x 20 kitchen also wanting good bath/ bedroom space probably still stands.

Thanks so much for your replies, really good to know will be approx £200k-ish, we definitely appreciate we need all the help with can get with the decision to buy/not to buy because we have a really small search area (walking distance to sons school) so not many options unfortunately.

Garden is really good size, not going to take up any garden space for the extension because it has a large gap down the side that we'd extend on :) we'd still be left with off-road parking for at least 4 cars.

My gut instinct is that it would need to be 2-storey extension too or the upstairs will be disproportionately small.

We've just put in for planning for a 2 storey extension, our architect advised that we're looking at approx £2.5k per sqm.

From our experience, do not underestimate the cost of a new kitchen (or bathrooms). Costs of ovens/hobs/fridges etc. Plus work top! And that looks like a large kitchen with potentially plenty of work top.

My general rule of thumb, whatever you think it will cost, multiply by pi.

Once you add in everything, I'd be surprised if you got change from £250k

We were advised this also at building regs stage, for a single storey extension. After going to several builders, we are looking at £3400 sqm to a shell finish plus having to supply the glass and skylights

One of the various problems with the "£X per square foot" thing is that on jobs like this the extension is only what part of what's needed. The OP's project will likely cost as much for the remodelling and refurbishment of the existing shell as for the actual extension.

There are a lot of unknowns here. How much remodelling is proposed upstairs? Are there new bathrooms to go in up there? In any case, I'd be surprised if it cost less than £250,000 with a two storey extension and fitting everything out. Even that won't get you top end finishes, just reasonable quality normal looking stuff.

Oops