Is this a crazy idea for a conversion?

[HarmonyHedges]

I have a maisonette apartment on the top floor of a converted church, which looks similar to the building in the picture—without the dormers (as indicated by yellow arrow) in the roof.

I'd like to add two of these style of dormers to my roof to convert the attic into living space.

Any ideas on approximately how much this would cost? Even a rough ballpark figure would be helpful. I'm in SW England.

If anyone has done something like this please tell me all about it!

You need to check if the loft is demised to your flat.

www.designingbuildings.co.uk/wiki/Demised_premises

Where I live in London every other top floor flat for sale the first thing potential buyers want to know is if the loft is demised.

So if it doesn't say that on your lease then it's not yours & you'll have to purchase it from the freeholder.

Around here dormers are generally permitted on the rear of properties, virtually never the front & costs start at £40,000 but are often more.

@MooseBeTimeForSummer

But if the roof leaks, are all owners expected to contribute to the repair?

Yes, that's correct. The freeholder doesn't cover any of the maintenance costs of the buildings so the leaseholders have to pay for anything designated as 'communal' (roofs, walls, windows, external doors etc).

@Dogsandbabies

The fact there is no lease doesn't mean you own the attic. The freeholder does. And they can create a lease and sell it to you.

Hopefully they would do that. Or just give permission to alter the roof, for a fee.

Around here dormers are generally permitted on the rear of properties, virtually never the front & costs start at £40,000 but are often more.

Yikes!

The loft is definitely not demised.