Extension expense and planning permission orders

[Hann12]

Hi
I was quoted for our extension (we are in Surrey) last year at £175K including vat for ground floor out the back extension (5m x 8m, and side 1.4m x 8m) and first floor extension out the back by 3 m ( 7m wide) and rebuild of a utility room (currently a lean to). We committed to the builders (paid a £3k deposit) and having plans drawn up but wanted to add a bathroom upstairs so wanted to go out the side upstairs too, effectively mirroring below, so out by 1.4 metres). Anyway they have come back with an updated quote coming in at £213k. This is way above what we expected. Maybe I was being silly but I didn't expect that small space to add £40k.
I'm trying to get hold of the builder to talk it through but if we can't come to a price reduction we need to decide what we can do.
If it came to it is it possible to put planning permission in for the ground floor and middle floor mirroring the top quote of £213k but only actually build the ground floor initially next year, and then in 18 months build the middle floor? Or would you have to make that decision now before we submit planning?
We might end up having enough to do the whole thing but it depends on bonuses so we don't want to commit if we can't but equally don't want to lose the opportunity to do it.
If anyone can help please let me know, thanks!

Your first quote is around £2400 per m2. As it has to be joined to an existing house it feels a bit high but it would depend on construction methods and finishes such as bricks, roof and windows etc.

You are now adding another 1.4 x 8m (is that right?) so around 12m2. This may cause the ground floor extension to need strengthening and deeper foundations. Hence extra cost. However 12 x £2400 is £28,000 so £40,000 looks expensive. I think that as you are captive, so to speak, they have tried to get money out of you. When you add the two extensions together though, that is the size of a small house!

Yes, you can stop part way through an extension but obviously it needs to be watertight. Would you put the roof on and then take it off again as you build the first floor later? This is expensive and will eat into the budget even more.

Present the builder with both £ per m2 calculations and ask why the 1st floor extra extension is so much more at around £3333 per m2. This doesn’t seem reasonable to me. I guess there needs to be access to this new space and further joints with the existing house but I would ask for a breakdown of the pricing because it seems unreasonably high.

Get planning permission for the whole lot. Why have you paid builders anything without pp? Get pp, get detailed plans and then get various builders to quote. Getting piecemeal planning costs more. It is more difficult to build on top of a building than it is to build from scratch. As I said above, you should be looking for a variety of quotes. You have very high quotes too.

Thank you, thats helpful. I paid the deposit to them to secure the date of the build (March) and for them to pay the architects as we are using theirs. So will will have all that done at least. I'm waiting for them to call me to find out about why the cost has gone up so much. Admittedly its a huge extension, which we knew, but we thought we'd be able to do everything including kitchen, flooring etc for £250K whereas now its looking more like £300ish, which blows the budget

It's seems very expensive in general - I assume it's fully finished and it includes the actual bathroom for that? We paid £1300 /sq m which I thought was high but all the cheaper builders seemed dodgy.

Is this new quote including plumbing for the bathroom though?

If the bathroom is above the kitchen it’s easier than if the plumbing has to be changed significantly. £1300 would be cheap for Surrey but the new price is too high. I think you are paying the price of gong to a “one stop shop”. A separate architect would have known several builders who could have quoted. You could have asked for quotes from different architects and talked to them for ideas. Unfortunately you have backed yourself into a bit of a corner so try and negotiate out of it.

The trouble is that we were okay with the original quote, so it’s annoying it’s been upped so much. The builder is off work today so he’s going to call me tomorrow so i’ll be able to find out what he’s done. Perhaps i’m missing something vital but it’s still very pricy.
The price includes an allowance for bathrooms and plumbing (3 bathrooms but i’m not putting 3 in so that needs to be adjusted, although doubt that will remove £40k off the price!). It includes an allowance for electrical of £9500, which seems huge but apparently their electrician is excellent, although we don’t have to use them,
It also includes huge flat roof windows - i’ve Asked a local company to quote for me on those now.
So in total it’s for the actual build, the installing of a kitchen, windows (but not 2 sets of bifold doors), internal doors, an internal glass balcony, electrical allowance, plumbing, a sunken living area, external door, allowance for bathrooms, radiators.
I think that’s about it.
So we still need to pay for: actual kitchen, tiling for bathroom, flooring throughout, bifold doors x2, decorating

Your quote seems really reasonable actually. We're in the NW and paid about £2k per square metre 2 yrs ago, plus VAT, which is what your original quote works out at (roughly).

You're then looking to add another 11.2 sq m so that's roughly £27k inc VAT and it's gone up by £38k. Arguably it's £11k more than it should be using the same pricing structure. But maybe this particular addition means more steels / more plumbing / more internal works / a different pitch to the roof. It's worth asking the question for more of an explanation but if it's a reputable builder that's come recommended, I wouldn't be losing the March slot over what you perceive as a big increase.

I don’t want to lose the slot to be fair, and I want to do everything, it’s just more than I anticipated. The builder turned out to be on leave today so i’ll have to speak to him tomorrow and see how it’s worked out

Have underfloor heating! Radiators are not brilliant in new builds. Sunken floor (?) is expensive. Your roof lights will be expensive if they are big and costly to install. They are worth it though. I have an internal glass wall and door and a glass balcony won’t be cheap. I think you don’t have a standard extension so the price is quite high.

It’s definitely not standard which I appreciate does bump the cost up.
I’ve now spoken to the builder and he’s revising the quote downwards. This should mean we can do it but just may not be able to do the second floor side part, but in the scheme of things that’s not the end of the world and not worth the £40k price tag for it