Cost of an extension - Cambridge

[codeninja]

Hi all. We are looking for a two storey extension in Cambridge. The area to be built is around 55 sq.m

It includes a new kitchen, utility, family bath, and a new bedroom with an en-suite.

We have got quotes which vary a lot. What’s the average price that we can expect to pay for a solid brickwork construction?

TIA

I don't know about Cambridge but I'd hazard a guess a minimum of £150k. Could vary a lot depending on finishes (kitchens could cost £50k on their own).

I reckon you’d be pushed to do it for under £100k, tbh.

@mondaytosunday - Thanks for the quick response. Is 150k including/excluding VAT?
Understand that kitchen/bathroom fittings could vary a lot. Hence I am looking for a ballpark figure without kitchen/bathroom fixtures.

We are not a million miles from you. For a 19 square metre extension plus about 6 square metres of space internally that needed some reworking (turning old galley kitchen into downstairs loo and utility), our quotes ranged from £51k to £86k before VAT. That’s traditional brickwork construction and pitched roof to a plaster finish including second fix plumbing and electrical work. VAT, cost of actual kitchen and sanitary fittings, and fitting said kitchen, plus decorating, all on top.

Depending on whether you include the original space to be reworked into the quote, we are paying between £2.3 and £3.1k a square metre before VAT.

Given that to build to the second floor is not double the cost of building a single storey extension, but allowing for the fact that that’s probably a lot of new plumbing, I’d probably estimate yours would cost around £120-£150k before VAT and fittings. What are the quotes coming in at?

@MyBuggyIsOutToGetMe - Thank you for the detailed information. Our spec is similar - pitched roof/traditional brickwork. The quote I have received includes the following

1. second fix plumbing and electrical works
2. cost of fitting the kitchen (excludes supply),
3. new boiler, wet underfloor heating to some parts of new extension (about 20 sq.m) and digging the existing areas in the house for wet underfloor heating(about 35 sq.m).
4. Moving a manhole within the property

Quote excludes

1. Decorating
2. Tiles/Flooring
3. Supply of Kitchen and bathroom fixtures

Quotes vary from 110k - 150k excl VAT.

We haven't done any building work before and hence would call myself a rookie. So, a bit apprehensive to go on quotes at the lower end as I don't know if there would be a compromise in the quality which we may not be able to spot. At the same time, we don't want to be spending too much for the same work and hence wanted to get a general idea.

Builders we have spoken to don't seem to give a detailed breakdown of costs. They just list all the work and an overall cost.

@codeninja , those quotes sound in the right ballpark though I appreciate it’s a wide range. We also found the level of detail varied hugely. Any differences between the companies in terms of size, number of staff working for them, availability, etc? How many quotes have you had?

My not very scientific approach was to aim for at least 3 quotes so I contacted eight firms, of whom 5 went on to quote. I knocked off the most expensive one immediately as he clearly hadn’t delivered on timescales promised when doing a neighbour’s property and was open about charging “profit” on his quotes.🙄 I then narrowed it down to availability and who I liked most and thought would be easiest to work with/who was most realistic about timescales and getting the work done. Those happened to be the middle quote and the second cheapest, and we went with the middle one on availability grounds.

So I would say don’t be afraid to go with someone who quotes lower as long as you’ve checked them out properly and followed up references. A higher cost definitely doesn’t mean a higher quality of finish.

Also don’t be afraid to ask what is included - eg is the kitchen fitting cost dry fit only or does it include fitting/re-fitting appliances? If so, which appliances? If not, how much extra will this cost? Etc. I would not have had the knowledge to query the hidden stuff with our builder - I expected him to build to the standard specified on the building control drawings.

The obvious stuff that makes a difference in terms of finish is things that you either source yourself (kitchen, etc) or that you upgrade from the standard in the quote (eg different light switches to standard white plastic). Where we’ve accumulated expenses is where we’ve decided we wanted stuff that wasn’t in the original quote (but where it made sense to do it now, like add on a patio).

Not sure how helpful this is but we’re about 45mins from Cambridge and have recently been quoted between £260-280k for 100m/sq extension which would give us a larger kitchen and 2 en-suite bedrooms upstairs.

@PointyMcguire - is that including all the fittings for kitchen and bathrooms?

@MyBuggyIsOutToGetMe - I have got 3 quotes. One is for 100k but didn’t hear good reviews about the builder. The other two come recommended and both the quotes are around 150k. So was wondering whether to get more quotes or just settle for one of the builders. Based on the input from you and others in the group, seems like 150k is a reasonable quote. So might just go with that rather than shopping around more.

Thanks to everyone for helping out

In Cambridge a couple of years ago, I paid £104k inc VAT for adding 35sqm, about 2/3rds downstairs and 1/3 upstairs, plus conversion of a bedroom to a bathroom and a bathroom refurb. Then there was £10k of other stuff, patio work and a long list of things that you end up needing like decoration, flooring, stuff etc. Bear in mind that raw materials cost for steel and timber are now a lot higher.

I was told in 2020 that reasonably quality would be to allow approx £2000 per square meter for ground floor and £1000 per square meter first floor above for a completely finished product. Then 20% VAT. That felt a little light to me at the time.

I'd watch out for bargain quotes as they won’t get it complete and/or there would end up being over costs etc.

Ours was 55m2, kitchen, utility, bathroom. £210K inc VAT. Nothing fancy such as lantern lights or underfloor heating, most fancy was the hot water tap and the 3.5m bifolds. Very expensive out there now. This was April/may this year.