Anyone done a garage conversion? Expected costs?

Soldato
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22 Jul 2006
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Hi all,

We are currently in the process of getting quotes for a garage conversion...well if people actually turn up!

We live in a 4 bed detached with a integral single garage, the usual 7 year old new builds.

I'm wondering if anyone has done similar and could tell me rough costs.

Basically it's a window to be fitted at the front approx 1800x700mm bricked up the rest.

Floor is already concrete and level, just a bit if insulation needed at the front and then made to a finished room excluding decoration and carpets.

4x spot lights needed and 1x radiator to be plumbed in.

I would imagine a pretty straightforward job.

Should I be looking at £4,£5,£10k??

I know it can be a bit of, how long is a piece of string but need some ideas in my head so I'm not underestimating the costs.
 
Soldato
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Isn't there some regs around turning garages into rooms, a mate had major trouble getting it agreed from the council if I recall correctly?
 
Associate
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You would need building control sign off as you are making it a habitable space, as a starter for 10.
We got a quote recently to do something similar but our garage is on the side of the house. Chap quote just under 10k.
The other half spoke to him though and I told her they would need trial holes to check the foundation depth as it would likely be negligible so the quote we got could well have included other bits like underpinning and altering the joists to allow for higher ceiling (I haven’t actually looked at the quote).
 
Soldato
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In addition to building regs, for a new build I understand you need to check planning consent as they will have been allowed planning from the council under the proviso there is a certain quantity of parking spaces, and effectively you are removing one.
 
Soldato
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Cost me 20k to turn an already roofed ally (between house and garage) into utility room + garage office..

Spoke to several friends / builders seems it cost more that you might expect as it's a smallish job requiring various trades for short periods (which a lot don't like doing) bit of roofing, but of bricking bit of electric bit of plumbing bit of decorating a bit of windowing..
 
Soldato
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Thanks all.

In relation to the building regs we have a 2 car driveway already and if they kick up a stink can extend to a 3 if needed very cheaply.

It seems there are too many variables so will wait and hear back from the builder!
 
Soldato
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£10k as a minimum, maybe even more depending on the level of finish you want. The building control alone will be ~ £1k, £1k for the electrics, maybe similar for extending the plumbing for a radiator, £1k for the window. Then you need stud walls building and insulating, plasterboard over the top then a full plaster skim on walls / ceiling. If the garage has any external walls, you may even find that the cavities aren't filled.

The concrete floor won't be insulated either so it's going to be hella-cold, make sure you invest in a decent underfloor / carpet to minimise the impact.

Do you have gas / electric meters to be boxed in / moved too?
 

Jez

Jez

Caporegime
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The concrete floor won't be insulated either so it's going to be hella-cold, make sure you invest in a decent underfloor / carpet to minimise the impact.
He'll need to insulate the floor properly anyway to pass thermal regs :) I converted an old garage (double storey due to 45deg roof) at the back of my house, i used 100mm PIR Recticel over the existing floor, then a floating (chipboard) floor over that.

My conversion cost me around £4.5k-5k including French windows where the main door was (now faces garden, as it was at the back in the garden anyway), putting the first floor and stairs in, Velux windows upstairs etc, but i did all of the work myself bar the BC sign off.
 
Soldato
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He'll need to insulate the floor properly anyway to pass thermal regs :) I converted an old garage (double storey due to 45deg roof) at the back of my house, i used 100mm PIR Recticel over the existing floor, then a floating (chipboard) floor over that.

My conversion cost me around £4.5k-5k including French windows where the main door was (now faces garden, as it was at the back in the garden anyway), putting the first floor and stairs in, Velux windows upstairs etc, but i did all of the work myself bar the BC sign off.

OP has said that floor is already level with the house, in that case they'll be some serious remedy work needed to dig that out so he can add sufficient insulation to meet the thermal requirements
 

Jez

Jez

Caporegime
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OP has said that floor is already level with the house, in that case they'll be some serious remedy work needed to dig that out so he can add sufficient insulation to meet the thermal requirements
Yep he’ll need to dig that out then…or accept a step.
 
Soldato
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However much you think it will cost, double it.

Seriously. We had four builders to quote last year to basically build a wall, and fit on a new roof. Single detached garage into nearly a double. Back wall already in place.

£20k
 
Soldato
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Converted ours maybe 8 years ago and it was circa 18K I believe, cant remember exactly, possibly a bit more. The boiler was already in the garage so we converted the small back portion into a utility room, sink/washing machine/dryer and the front larger area into a 2 desk office. New window in the front and new door off the side into the hallway.
 
Associate
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£10k as a minimum, maybe even more depending on the level of finish you want. The building control alone will be ~ £1k, £1k for the electrics, maybe similar for extending the plumbing for a radiator, £1k for the window. Then you need stud walls building and insulating, plasterboard over the top then a full plaster skim on walls / ceiling. If the garage has any external walls, you may even find that the cavities aren't filled.

The concrete floor won't be insulated either so it's going to be hella-cold, make sure you invest in a decent underfloor / carpet to minimise the impact.

Do you have gas / electric meters to be boxed in / moved too?

Trades must be silly priced in Hants. My total bill for my plumber and my spark (combined) was under £1k in total for a 30m2 kitchen extension. Windows were around £300 each - glazed. Plasterer was around £600 inc materials. Building control was £450.
 
Soldato
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So price from the builder I was expecting to be the most as his top class is £4900. This is to get the room to the stage of decoration, so plastered with skirting on, additional electrical sockets and 4 additional spotlights and plumbing for the radiator.

This is only a 7 year old house so the floor is exactly the same concrete throughout so it's already insulated etc.
 
Man of Honour
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Echoing the 20K numbers - my brother converted admittedly an ageing garage with a few issues, added a front window and 2 sky lights, didn't get change out of 20 grand. That was a double length garage though, had a en-suite style shower installed and a reasonably expensive external finish.
 
Soldato
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Trades must be silly priced in Hants. My total bill for my plumber and my spark (combined) was under £1k in total for a 30m2 kitchen extension. Windows were around £300 each - glazed. Plasterer was around £600 inc materials. Building control was £450.

That sounds ridiculously cheap to me, but it depends on the extent of electrical and plumbing (was the plastering for the whole 30m2? Also sounds far too cheap!)
 
Soldato
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That sounds ridiculously cheap to me, but it depends on the extent of electrical and plumbing (was the plastering for the whole 30m2? Also sounds far too cheap!)

Yeah room is approx 30m2, the boiler and fuse box are all in the same room so not really too much bother.

I should have maybe put a photo in to make it easier for people to picture as going by some prices being thrown about.

osx7yhp.jpeg
 
Soldato
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Had another estimate of £4k.

£1k for the window and bricking up of the door then £3k for the internal works to get it to a level ready for paint.

This quote is an estimate as the fella is booked up most of the year and as I'm not in a position to book right away didn't want to fix in which is fair enough.

With this in mind I hope I can get my preferred builder down to atleast meeting in the middle at £4.5k.
 
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