Rough estimate on extension

[NotAGolf]

We've found a house we like the look of, but it needs a fairly substantial amount of work. We're trying to get a rough estimate for the work involved.

The work is as follows:
- Removal of a coupe of internal walls, which will involve fitting at least one hefty steel.
- Knocking down the garage, rebuilding a double story extension in it's place. The garage is currently ~1m away from the house and not attached. Assume we will have to knock it down and build in approximately the same footprint (attaching it to the house obviously)
- Replace kitchen
- New bathroom in upstairs extension
- New toilet in downstairs extension
- Replace existing bathroom suite
- New boiler
- Move gas and electric meters,
- Move consumer unit
- Wiring, plumbing, plastering, flooring, etc for 4 small rooms in the extension

Here's a floorplan of the property for an idea of dimensions/layout etc

Assuming the finish is average quality. I.e. not cheap, not high-end. Any rough ideas of cost? In our highly uneducated opinion, I'm thinking possibly around the 150k mark? Possibly edging nearer 200k.

I realise this is very rough, but even to the nearest 50k would be helpful. We're based down on the South coast.

 

[Deleted User 298457]

£150k probably gets you a two story extension and the demolition work. I'd factor another £50-70k for fixtures and fittings in the boiler/plumbing/kitchen/downstairs wall removals.

Not much change from £250k basically..........a lot of the work you are planning will present opportunities it'd be mad to not exploit e.g. re-wire/insulation under floor/ground source heat pump etc...

 

[Hedge]

Have you checked if any similar houses in the area have had extention work like it? Check how much extended homes have sold for too because you could end up in negative equity if you go over the top in a place where values don't reflect it so well.

 

[NotAGolf]

Have you checked if any similar houses in the area have had extention work like it? Check how much extended homes have sold for too because you could end up in negative equity if you go over the top in a place where values don't reflect it so well.

Negative equity isn't a concern as our LTV very low. We're not concerned whether the work will pay for itself either, as this will be our forever home.

We're trying to work if a) we can afford it, and b) would we be better off waiting for a house with a larger footprint that doesn't require quite so much work.

There's also a concern over whether we'd get planning permission, but that's another story!

 

[Buffman]

At a real rough finger in air I'd say 200 to 250k. If you get a reasonably priced builder might be a lot less but thats rare as rocking horse ****

 

[Rob200sx]

Negative equity isn't a concern as our LTV very low. We're not concerned whether the work will pay for itself either, as this will be our forever home.

We're trying to work if a) we can afford it, and b) would we be better off waiting for a house with a larger footprint that doesn't require quite so much work.

There's also a concern over whether we'd get planning permission, but that's another story!

If it were me, I'd want to be as sure as possible it would get planning permission, otherwise this is then not your forever home, it's just another step towards it. A local architect should be able to give some advice as they'll have experience with local planning.

 

[Gav_r26]

From doing our extension, my advice, would be anything that involves utility companies moving services will be expensive and painfull! We needed an openreach telephone pole moving and it was the worst part of doing the renovation, and took nearly the longest! So it you can avoid moving it, do! I assume they are on the wall in the alley between the house and garage, so maybe look at boxing them ina cupboard or the like.

 

[sovietspybob]

From doing our extension, my advice, would be anything that involves utility companies moving services will be expensive and painfull! We needed an openreach telephone pole moving and it was the worst part of doing the renovation, and took nearly the longest! So it you can avoid moving it, do! I assume they are on the wall in the alley between the house and garage, so maybe look at boxing them ina cupboard or the like.

Yeah that's a good point, we did a new build 8 years ago and just getting BT to put up a pole took wayyy longer that seemed reasonable and cost 5k, plus they had an entire empty plot to plonk it into and still seemed to faff about forever.

 

[Hedge]

Negative equity isn't a concern as our LTV very low. We're not concerned whether the work will pay for itself either, as this will be our forever home.

We're trying to work if a) we can afford it, and b) would we be better off waiting for a house with a larger footprint that doesn't require quite so much work.

There's also a concern over whether we'd get planning permission, but that's another story!

When we extended ours I looked at the council planning portal which helped me see what kind of things had been approved in my area. Worth a look if you can find a similar site for your area.

 

[daz]

The biggest variation is going to be related to the quality/expense of the kitchen and the bathrooms. Also flooring can add up significantly. We did a similar 2 storey extension in 2021 and it came in at £175k approximately. We had issues during the build related to supplies, so we ended up with scaffold on the house for much longer than expected, but luckily we mainly came in on budget. That's in the South East, and I'd probably expect it to be nearer £250k now with labour and materials going up significantly since then.

The other option you potentially have is to do one storey now, get your open plan downstairs area etc, but build the foundations strong enough to potentially support an upstairs extension later? It will be the roof coming off your house that in my experience will be the most disruptive part of the build.

 

[Gav_r26]

The other option you potentially have is to do one storey now, get your open plan downstairs area etc, but build the foundations strong enough to potentially support an upstairs extension later? It will be the roof coming off your house that in my experience will be the most disruptive part of the build.

I believer these days all extension have to have foundations for 2 storey, even if only one, incase someone adds a second floor at a later date. Think building regs spec it.

 

[ttaskmaster]

I would say, 'bout tree fiddy....

Partly for the obvious reasons, but also because so many of these things seem to overrun nowadays. It's certainly worth having a good chunk spare in addition to the highest estimates.

 

[Demon]

Yep, just based on post COVID inflation, £250k+ for that lot would be my reasonable estimation.

If you can handle some pain, then you can always do it more cost effectively..
1. Get a good builder to just do the fabric, many more builders will be happy and some prefer just getting to a plastered finish with electrics and basic plumbing done.. then get different trades/companies in for kitchens, Toilets, decorating etc..
2. For electricity, if your meter is already on an outside wall that will become an inside wall, you can save money by leaving it roughly were it is.. that's what we did, it sticks out 4cm from the plaster so got the carpenter to build a small hidden door cabinet around it. that saved £6k.
3. For gas, if main feed intersects the new boundary wall, then your builder might as well excavate the feed pipe back and create a 1m2 access patch around it, probably take him a couple of hours whilst he's digging foundations, ours did, and capped off the gas meter/main feed (using an appropriate Gas engineer), it only cost £600 for the ground box and meter connection, saving another £2500

The problem is
1. You need to be more organised and know where you precisely want your hot/cold feeds and wastes, so have to have planned kitchens/bathrooms etc and thought about things carefully so the builder puts everything in the right place.
2. It will take longer.. so living more ad-hoc and being creative should be something you are prepared to do.. we used a lashed up electric oven on a table, that and a single camping induction hob and combi-microwave for 9 months was OK, I even lashed hte washing machine up in the middle of a room.. it got us through.. and because the gas was being moved, I did have an electric shower installed for £500 prior to work starting..

I found a great builder, and effectively we paid £75k for the 9m x 4m double story side extension (plastered finish + electrics + basic plumbing) and £29k for the 6m x 3m single storey rear extension (including electrics/basic plumbing and 3 x electric velux windows).. then I DIY'd a lot.. so kitchen and utility to highish spec was £14k inc appliances for both rooms.. flooring was £1.5k.

Neighbours 3 doors up have planning for a similar side/rear extension (slightly smaller, but fiddly) and opening up inside, with kitchen and boot/shower room and doors/skirting/painted finishes came in at £275k! They have had a quote off our builder, £148k to the same plastered/electrics/basic plumbing spec, and they've had quotes for Kitchen/boot room/shower/carpentry and flooring for £48k, so £196k total, saving a fortune..

Ironically I thouight that OK, but they aren't planning on staying and it only adds £165k max to the value, so have decided not to bother..