Choosing a roof for a single story extension

[JohnyG]

Hello, I'm in need of some advice regarding a single story extension please.

 

The section of the house relevant to the extension looks like this.

At the far side is a large building attached to the house.

 

We'd like to extend the house outwards by 3m and I'm unsure what kind of roof to use particularly because of drainage. 

 

Ideally we'd like some ceiling height so I was thinking of something like this below. The red arrows show how drainage might work, I assume it would need some kind of central valley gutter made from lead?

 

A

 

Here are some other options.

B

 

C

 

D

 

If anyone can give me some advice if pic A is feasible or whether I should be looking at other solutions for this?

 

 

Many Thanks

[kandgmitchell]

Well D has to be the easiest to achieve with the flat roof covering taken up under the existing tiles and a simple abutment flashing against the house (plus cavity tray if applicable). A probably the worst as it's a stepped flashing against the house and a central gutter to form amd maintain. B and C are variations of the same thing with a secret gutter against the house. Myself I've always thought getting the rainwater off over the edge of the building straight away is the best option rather than collect it and rely on transporting it across the building.

 

Looks wise I'd say B and C but for ease go A.

[crispy_wafer]

C, would be my vote, alternatively lift roof off, and new roof trusses to span across the old and new.

[goodbyegti]

On 25/03/2025 at 10:40, crispy_wafer said:

lift roof off, and new roof trusses to span across the old and new.

^ this, if planning allows!