Detailed builder quotes vs much cheaper estimate for extension

muchembe

We have planning permission for a single story front extension of 40 sq m, partly replacing a side garage, to include bathroom, dining room and utility room. We have sent detailed plans from our building regs app to three builders. All have great online reviews and have provided contact details of previous clients.

The builder recommended by our designer gave a detailed quote around £100k. An FMB registered builder gave a very detailed quote also around £100k. The third is also FMB but rather than a quote gave an estimate of just over £60k.

The estimate guy says there are too many uncertainties in this kind of work for quotes to be reliable and that his experience means he is usually within £5k or so.

It feels like the £60k is in too good to be true and most likely a bid to get the work, after which costs will rise. On the other hand they'd have to raise a fair way to reach the other bids and £40k is a lot just to say goodbye to.

Should we write off the lower bid, or follow up on their previous clients and see if we can find out whether their estimates really are that reliable? If we choose between the two £100k ones how much weight to give to FMB plus super detailed quote vs our designer's recommendation?

twopenny

Really the cheap guy can't detail because he doesn't know what may arise but the other two registered can provide detailed quotes.

Perhaps they have the experience, skilled labour to hand and have done similar jobs before so are confident in giving you specifics you can hold them to.

It is true that there is no telling what may arise but that's the nature of building to that extent.

My personal opinion is a neighbour had similar done with a new extension at the top price you gave so it's reasonable. And I would not employ someone who can make no judgement on what needs doing.

muchembe

https://forums.moneysavingexpert.com/discussion/comment/81858055#Comment_81858055

Thanks @twopenny I think you may be right. It is hard to be sure what is going on. We'll probably try to chat with some of the former clients before taking a decision. The £60k for 40 sq m does seem too low to be feasible, in fact even £100k doesn't look high going by the £3-4k per m sq I've seen mentioned in these forums. The temptation is to go for the lower bid in the expectation costs will then rise but hopefully not to beyond the other builder's quoted £100k.

twopenny

Yes talking to other customers is a good way to go. I live in a small town and watch when I see a company, how they work and what sort of house. Still make mistakes though through a long life.

I do know I chose a reputable builder to do the paving all round the house despite lower offers. Lovely job, no hassle and he came to see the mens work before, after and checked all was ok. Looked brilliant, set the house off. Would do it again.

Good luck 🙂

Albermarle

The costs will depend also on what the final outcome.

Some will quote just to build a waterproof box.

Some will include electrics, plumbing etc.

Some will include fitting out the bathroom for example.