Converting + Attaching Detached Garage

kitkat9933

kitkat9933

kitkat9933

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We are looking at purchasing a new property (Georgian House) that has a large but basic 36m2 garage about 1m away from the side of the house.

To make an additional large open space, we are thinking about opening up what's labelled the Kitchen/Dinning room (moving the dinning room to one of the other sitting rooms) and then bridging into the detached double garage (which will mean we will need to knock down and connect the two buildings together) to make a large open plan kitchen/living space.

I've no idea how much this type of project should cost and no builders will estimate it as we don't own it yet. So was wondering what sort of costs I should plan for so if anyone could help it would be much appreciated!


Some things I do know the price off:
  • Large 5m wide patio aluminium sliding doors + some velux sky lights+ some front windows into the garage ~ £7000 inc ifitting
  • The garage has power, water and drainage already.
  • Roof is in good shape
  • the garage has front and rear doors that will need bricking up/replaced by windows.
  • a steel beam will be needed to extend the kitchen/dinning room

Is £50-60k for the building works (excluding fittings/furniture and the kitchen itself etc) realistic?


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I can't give an expert opinion but when I was looking at a new house with a detached double garage (around 2 feet from the house) it was estimated at about £30k to make it a habitable space and attach it to the house but I wasn't going to have the house wall taken down so that will likely add a fair bit more.
 
I think your probably 20k short opening up the wall of the house to make it feel open plan is going to be costly and that garage is huge!
 
It'll make a huge difference to the property, an open living space that big.

If the garage has a flat roof you might need to factor in some reinforcement.
 
Participant said:
It'll make a huge difference to the property, an open living space that big.

If the garage has a flat roof you might need to factor in some reinforcement.
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And I think i’d Want a roof light or three to really brighten up the place that’s the sort of thing you don’t want to do post completion when you realise you wish you had!
 
fastwunz said:
You also need to focus on making sure it doesn’t look like a garage that’s been converted into a glorified conservatory - not easy
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Will be impossible to integrate with the rest of the house as it will be totally out of keeping so will always feel like the hanger on the side! Will make the house epically bottom heavy as well I guess.
 
You are probably going to have to consider digging the floor slab of the garage up, to install insulation. Otherwise that space will always be cold. If you are going to dig it up, you may want to look at installing underfloor heating ? Even if you dont put underfloor heating in, will your current boiler be big enough to heat that space (especially as you are looking to add some largish heat-sinks in the ceiling). I am guessing (assuming good insulation in the walls and roof) that you are probably going to need at least an additional 15,000 BTUs in heating
 
Psycho Sonny said:
you can add another £15K onto the budget then. Large glass panes aren't cheap especially if being used as walls.

why not just keep it separate and turn it into a games room?
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As we want a very large open kitchen/living space. The house is fairly large with many rooms, but being an old house, not many make sense for this type of space.
 
You have a change of use. Prepare for lots of planning and regulation..

If you did this and tried selling the property you may have issues.
 
kitkat9933 said:
As we want a very large open kitchen/living space. The house is fairly large with many rooms, but being an old house, not many make sense for this type of space.
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I think your quote is way out then.

Knocking down the wall if doing it completely open. Will need a beam putting in and proper support.

Again on both sides. Could be £30k just for that.

I'd say if you can get it done for £100k with the glass link then that would be good.

For this type of job though I would only get pros in. No cowboys who will take shortcuts with a poor finish.

I know builders who have been building houses for 30 years and still cant make a straight wall or fit a door properly. They are cheap though so constantly busy with work.
 
I would knock down the garage and build something purpose built. Garage conversions always look like garage conversions and pretty much all garage conversions look naff.

As others have said, you'll run into issues that make it not impractical like insulation, heating, floor heights and looking like a garage with windows instead of doors. To make it look right you'll probably want to put on bi-folds in the back to get the light in and open up the space to outside.

The other option is to buy a house with enough downstairs space instead of trying to 'bodge' on an extension on the cheap.
 
b0rn2sk8 said:
I would knock down the garage and build something purpose built. Garage conversions always look like garage conversions and pretty much all garage conversions look naff.

As others have said, you'll run into issues that make it not impractical like insulation, heating, floor heights and looking like a garage with windows instead of doors. To make it look right you'll probably want to put on bi-folds in the back to get the light in and open up the space to outside.

The other option is to buy a house with enough downstairs space instead of trying to 'bodge' on an extension on the cheap.
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thanks for the advise. I’m not trying to build an extension on the cheap, but work out what I should put to the side to do it properly. Cheap is not in my vocabulary ;)

There aren’t many houses over 2,500 sq ft in the area we want to move to for work, except new builds which are a no no.
 
No worries, I get you don't want to cut corners but the whole point of using the existing structure is to cut costs at the expense of aesthetics, particularly the roof-line and it looking like a garage that has been attached to a house when it wasn't meant to be. I just don't think you can do it 'properly' using the existing structure.

By re-suing the existing structure you are certainly making compromises and risk having other issues like insulation and floors not lining up correctly. The glass bridging roof will also be annoying, it will be loud when it rains (it rains a lot here) and will need constant maintenance to keep it clean. For example I have a small sky light on my en-suit and its 'sub-optimal' if the door gets left open and it starts pouring with rain in the middle of the night, if your trying to watch TV it will just be incredibly annoying. It will also haemorrhage heat in the winter making the room feel cold.

For me knocking down the garage and building a purpose built extension onto the side of the house would look so much better. You could go the whole depth of the property and create a really nice, large space. You could put on a nice high vaulted ceiling to make the space light and airy. You get the light in using large bi-folding doors on the back to the garden and a window on the front.

You would probably still have enough room for a single garage on the side, personally I wouldn't consider a house without one so it also has the potential to devalue (or not really increase its value even though you spent tens of thousands on it) the property because of the loss of utility and the inevitable odd looking frontage.
 
I think that the OP needs to engage an architect and / or a QS to give him a professional opinion based knowledge and experience. This is likely to give him the best options available and accurate costs.
 
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