Estimating extension cost for remortgage

[williamglossop]

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.

 

[kingandy2nd]

Work out the floor areas in square metres for both floors, add together, and multiple by £1,500.

 

[williamglossop]

Does that still apply when the ground floor is a garage? And to what level of finish?

 

[denso13]

Does that still apply when the ground floor is a garage?

Yes, but it is only an estimation. If you need a precise figure you'll need to get some quotes.

 

[williamglossop]

Coming in at 85 grand. No way that's right for a garage with a bedroom above it with no internal finish. I don't wanna mess anybody around by getting a quote and realising there's no way I can afford it.

 

[denso13]

I don't wanna mess anybody around by getting a quote

It's the only way you'll know for sure.

 

[^woody^]

The problem is that if things are tight and you underestimate, or if there are problems or unforeseens you don't take account of then you are stumped. Is an over estimate a bad thing? Can any excess be added back to the mortgage account to reduce the payments?

Look for similar two storey jobs recent or ongoing around you, and ask the builder for a rough estimate. Pay a few quid for a builder (who you have asked if he has done recent similar work) to visit and give you a no-obligation estimate.

 

[kingandy2nd]

You can times the sq m by 1,000 if it makes you feel better about it.

Even if you only want the shell built you’ve still got to kit out the insides eventually and that stuff costs money too

 

[denso13]

You can times the sq m by 1,000

Or £500, even better.

 

[kingandy2nd]

Or £500, even better.

That’s what I did for mine - even building it myself it’s cost more than that in the end.

 

[A_Novice]

The rate per square m would be dependent on where you live as well. £1500 in the Southeast where I am would be cheap

 

[Old Salt]

I used £1500 and should have doubled it for the SE. Did it for £20k as a shell and finished modernising the whole house for the other £20k. Maybe slightly over that by the time we finished the bathroom.

 

[thomp1983]

In Nottinghamshire we were quoted £55k for a 14mx4m single storey extension across the rear and 6x6m garage with 2 rooms on top on the side they were both just to be watertight shells.

 

[kingandy2nd]

In Nottinghamshire we were quoted £55k for a 14mx4m single storey extension across the rear and 6x6m garage with 2 rooms on top on the side they were both just to be watertight shells.

Bargain! When do the start?!

 

[thomp1983]

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.