2 storey side and rear extension in Northwest… 150k enough?

[Lenor]

MIL isn’t in very good health, and has made the decision to sell her home. From the proceeds, she’s like to extend our current family home with a granny flat for her. Due to the layout of the garden she would have to be attached, and she is incredibly keen for it to be two storey (we have 3 daughters and a 3 bedroom, she thinks it’s very important they have a bedroom each).

The extension at the side would be adding a living space, kitchen, shower room and bedroom for herself, two extra bedrooms upstairs and the extension at the back would be to our current living space and would include a new kitchen and downstairs toilet. We’d be looking to add roughly 52sqm on the ground floor and 32sqm upstairs.

MIL is adamant that 150k will be enough to cover all this, but I’m worried it won’t be. We’ve reached out to local architects but I’ve heard often time on here that architects idea of costs aren’t very accurate. We’re still waiting for them to get back to us.

Those of you who have done similar extensions, what do you think?

We're currently doing a loft conversion in the north west. 2 bedrooms/shower room and don't need planning permission as it just comes under permitted development. With the new roof and render to the whole house it's coming in at around £88k if that's any help. The double dormer is a significant cost so you might get some back that way?

Architect reckoned on about £50k, builder base price was £66k without the roof/render/bathroom & labour and fees. We've added 49.48 cubic metres

I think you’ll have to get local quotes. You can Google cost per sq m of build in your area? I think prices will come down this year.

I have just finished a wrap around single story extension. 2.5x 5m at back and 2m x 5m at side. Construction costs were £65k. With kitchen, utility room, flooring, new downstairs loo etc the total budget is £110k.

I think £150k would be tight for what you have described

Remember the build cost estimates don’t necessarily include plumbing and electrics.

I planned quite well but forgot about the cost of radiators!! And redoing the paths and patios outside.

We are in the northwest & have just done a small extension. As a guide , our builder suggested approx £3k per square metre.

@Lenor I'm in the North West and we completed a double storey side and single storey rear extension last year. We paid £3.5k per square meter plus having the driveway and garden sorted following the build so I think your budget will be tight.

Thanks everyone. I believe cost per sqm in our area are 2.5-3k, but I didn’t know how to factor in the second story. My MIL seems under the impression that adding the additional floor is much less than 2x the price, would anyone be able to advise?

It is cheaper as you already have the foundations and you have to add the roof anyway. £150k sounds plenty.

My DH works in construction and says (although not his specialty!) that 150k to build, put plumbing / electrics in, board and plaster out, fit out (flooring fixtures and fittings etc), get doors and windows etc is sounding light to him for almost 100sq m. Let alone furnishing etc. He said although local builders might have more availability currently because people are cancelling work, they're not expecting a huge drop in materials cost (some will be getting even more expensive). He says also take what you think it will cost, what you get quoted and add another 20% on for a slush fund.

Builder told me £2K per square meter for single storey.

i am intrigued that you think the £150k
is plenty. Can I ask if you have had works done recently? I really struggled to keep by budget down.

maybe it’s the two stories that makes it cheaper? Do you thinking the £150k is plenty including the electrics, plumbing, new kitchen and new show room?

I know you can spend as much or as little in a kitchen as you want. My kitchen and utility budget is £30k - but that includes some luxuries like quartz worktops, drinks fridge, boiling water tap etc.

So we did a similar extension - we did a single extension out the back of ‘our’ house, then we did double height down the side.
We added 2 bedrooms, 2 bathrooms, kitchen and living room in the side extension and then a big kitchen dining room and another bathroom in our bit.
We are SW and all in I reckon we spent a good £230k. We started in jan 2020, so we didn’t suffer from all the price increases post Covid.
We saved in some areas and spent in others, but some things aren’t cheap and not cheap to do (tiles and tiling for example!). Oh and VAT. The architect had no clue about pricing.
We had to upgrade our central heating system as well - we have kept the boiler (was a bog standard combi boiler) but we had to add a water tank and expansion tank thing to cope with now being a 5 bed house. We then put a cupboard all around it all and put the washing machine and tumble dryer in there, so my mum didn’t have to have one in her kitchen.
I think it’s the best thing we could ever do house wise.

For starters, don’t use an architect. Look at your local weekly planning lists and find an agent that submits regularly. Having a RIBA architect just adds to the cost when a competent technician will do plans for much less.

I think 150k is reasonable for 84sq m, but only just and it doesn’t leave you any contingency.

Thanks everyone, these replies are really very helpful.

Whilst 150k is how much my MIL wants to spend, it isn’t the maximum she can afford to spend, if that makes sense. Obviously it is entirely up to her how much she contributes, but it’s useful to hear that it may well go over and to start preparing her for that now. There are several things we would compromise on… her not so much. I’d rather we all went into it with our eyes fully wide open.

www.mumsnet.com/talk/property/4609943-how-much-did-your-double-height-extension-cost-please

some good discussions here

also be prepared for how long it will take and if you can live in the house while work is ongoing.

We live in Manchester and did our extension in august 2020.
We did a 2 storey extension and added a 4th bedroom and extended the box room to make it a double upstairs, downstairs we added a utility, shower room, new kitchen and reception/dining room, all in it was 90sqm.
The build was £120k but that only got us to 1st fix. It cost £18k for the kitchen and another £1.5k for the shower and utility fittings, and another £4k for flooring. I decorated it all myself to save a bit of Money.
I used an architectural technician to do the drawings, then you have the council fees for both planning and building regs as well as a structural engineer for any steels you’re using, So maybe another £2.5k.
Also don’t forget to factor in VAT which adds another 20% to your bill.

You might squeeze it in for that. Can she wait that long though? The builder we used for our extension is now taking work for 2024. We booked him about 12 months in advance for a 2 storey extension that took 5 months to be a livable house. We needed to move out for most of it .
Unless your property can hold the investment, her money could be better spent else where.
You may be able to save some of the VAT as you are doing work to accommodate her health conditions, eg her bathroom, but this is 0 rated at source so you need to find a supplier who runs the scheme. A builder may also be able to do this section of the work at 0% VAT.