Cost of getting a 2 storey extension on side of house

[Jennywren8]

We have four children and the two youngest share a bedroom but are getting sick of being together and arguing a lot more. It's unlikely my eldest will move out of the house for at least a couple more years (if ever!)). We are a detached house with a garage on the side. We have enough space to knock down the garage (which isn't load bearing) and build a two floor extension on the side of our house but literally have no idea how much this would cost. We live in the midlands. Would anyone even be able to give me a ball park figure so I can work out if it's in the realm of possibility. Thanks!

We have a single garage which is attached to the house. We were quoted 25k about 3 months ago. This included digging up and raising the floor and creating a doorway through to the house through the downstairs toilet. We are in the south east so I would expect it to be similar or less in Midlands.

There might not be much difference in cost between a warm roof and a cold roof in new construction but when converting an existing building there would be a difference in cost.

Those days are gone. Or at least we have seen more like 3.5k to 5k and gone out to tender for our extension.

In OPs case yes.
I looked at their latest pic after I posted.
They’d have to remove the tiles and battens and replace so yes in OPs case certainly.

Could you tell me what the difference is between a cold and warm roof and what it would mean for us, which one would we need and would it add cost? Thanks

For recent reference; We're doing a decent size rear extension for 160k + kitchen, bathrooms & flooring. Quotes ranged between 140-220k

A cold roof has the insulation below the roof finish.
In your case very easy to do as long as your floor to ceiling height
, after the insulation and boarding is added, is ok.

A warm roof means the insulation goes in above the roof finish. So let’s say an existing concrete roof.
Insulation below concrete = cold roof
Insulation above concrete = warm roof

For you I’d think it is cheaper to put the ins below. But check your heights.

Here’s a nice pic too

You could extend the garage to the front boundary of the house and have a bedroom behind it if you needed more room . A garage conversion would be around £15 k I would think depending on where you live

This thread is really helpful, thank you so much for the input.