Estimating extension cost for remortgage

[kingandy2nd]

The build will be later this year, we're still awaiting planning and moving into the house, I'm still not sure we'll go with a builder as I fancy having a go at it myself as it's a relatively straightforward build.

Surprised any reputable builder would give you a quote before you had planning. If you can get a couple of similar quotes to confirm the price or some reliable references from the £55k builder then happy days for 128sq m of build. I suspect one of two things will happen for you with that builder, either you'll end up with a lot of additional costs added on, or you'll end up with a shoddy job as they penny pinch on materials, cutting corners, etc. Happy to be proved wrong though

To put this into to context for the OP, a couple of things from my experience when starting my build in 2018:

Loads of builders were busy then (and are more busy now as everyone has lockdown projects). I contacted about 12 builders and ended up with 3 quotes for my double story, 92sq metre build. My quote was for water tight shell only: Two quotes around £120k, one quote was £80k.

Great I thought, £80k is more like it maybe the others we just busy and didn't want the job. Had a few more conversations with Mr 80k builder, but they were one of these dad and son firms, no accounts, not vat, no history and although they'd been doing some jobs locally no local references for me. Then, the deal-breaker, they want a third of the money up front 'to get it out of the ground'. I declined of course, and since then I've seen a different builder's van outside one of the jobs they were doing locally, and I've never seen them around doing any other jobs. That might just be coincidences, but I think it confirms my fears.

Since then I've been self-building. Mine is a somewhat complicated build, with piled foundations, some steels and a re-reroof of my entire house. By the time it's water-tight I'm going to have spent £55k, and will still need everything internal done. It'll be £75k by the time I've done inside, but that includes about £10k for new kitchen/appliances, £4k new boiler. It's also been a year of hard slog and a hell of a lot of shopping around to get the best prices for everything...

 

[thomp1983]

I understand your concerns Andy, fortunately I've known the builder for a few years so I'm happy he knows what he's doing and he's got a good reputation, he's done some odd jobs for us in the past.

 

[Notch7]

I know 'cost' questions are everyone's pet hate.... and i'll fully expect the usual replies..... anything from a pound to a million, how long is a piece of string etc. But, never the less, ill try anyway.

I live in a 3 bed house that has a garage attached to the side. I have planning permission to remove the existing garage, and to rebuild it 1.5 meters wider, and then have a bedroom built above it. Its gonna be built in block work at the front and gable end with k rend, the rear elevation will be brick. I'm having the existing roof retiled at the same time, so it all matches. I have no idea how much to look at borrowing. I only need the shell building. I'll do the internals myself.

Am I looking at 50k? 60k? 80k? I have no idea at the moment. I'll attach the plans.

I'd guess at £15k founds to DPC, £20k roof, £20k walls, floor, ceiling =£55k for shell.

No plastering, plumbing, electrics, floor finish etc.