When does a covered way become a porch?

[DIYknot]

There is a narrow gap between my house and some old, low outbuildings (about 2200mm to the eaves with a flat roof sloping away from the house. At the back of the house there is a 3m tall retaining wall. (see diagram)

I’d like to build a covered way down the sideway so that I can walk to the outbuildings from the back door without getting rained on. Simple construction, just 47 x 150 rafters going from a ledger plate on the house wall to the eaves of the existing outbuildings, covered in twin wall clear polycarbonate, open at both ends. Total height would still be less than 2.5 m.

I think I would be allowed to do this without planning permission (correct me if I’m wrong) but my question is…

If I extended the polycarbonate to cover the back door as well does that turn my covered way into a porch? In which case would my covered way fall foul of the permitted maximum area for a porch. (it would be about 11 m2)

If this is the case, could I stop the covered way just before the back door and then install a separate little bit of polycarbonate roofing, say 1000mm x 600mm covering the door, ie a small cantilever porch? Would there be any minimum size for the gap between the two?

(the garden door does already have a free hanging porch over it so I don’t know if I’m allowed to have two. )

As a further thought, if I didn't attach it to the house but just had uprights very close to the house - say 100mm away - does is now become a car port and not need PP?

 

[Deluks]

Where is the front of the property, will anyone see it? I'd just crack on and not worry about it, unless you are in a conservation area or national park. (Or if you have busybody neighbours that you don't get on with!)

I take it you own the outbuildings that you are going to attach to?
It's a large surface area, so think about where rainwater will go, and how you will get it off and away from the buildings.

 

[DIYknot]

Thanks for the reply. The front is at the top of my sketch next to a large garden that slopes steeply down ending in a vertical drop to another house (odd arrangement). The nearest road is some distance away towards the back of the house behind the retaining wall - downwards in my sketch - so you have to walk to the garden door. I don't think anyone could see the covered way from any direction due to the walls and the house. The outbuildings are part of the property. I'd thought of having the polycarbonate finishing on top of the existing outbuilding roof so rainwater would drain onto that roof and into the existing gutter.

 

[Deluks]

Sounds like a plan, you could do it in 3x2 though.
Make sure your gutters above don't drip, if they drip onto that roof it will drive you nuts.
You might also need flashing on the house side of you want it to stay dry underneath, but depending on your existing roof overhang and location you might get away with it.

 

[DIYknot]

OK, thanks for the advice about 3 x 2. That will reduce the cost and weight.

 

[Deluks]

You might want to walk on it for maintenance or to apply fixings or flashing (With a scaffold or ply board on top)
With this in mind 4x2 might feel more solid, it will probably be cheaper than 3x2 anyway.