Creating an external door opening - any idea how much it would cost?

[thesaurusgirl]

I want to knock a door through an external (so obviously load-bearing) wall so I can have access to a flat roof. This I plan to turn into a roof terrace when budget allows.

It's a low priority (my flat needs everything doing to it) but I'd like to have it done at the same time as the kitchen so all the joinery is identical, and so I'm not looking at complex 'making good' when the roof terrace is installed.

I presume I will need to allow for a concrete lintel, the door itself (wood or steel and double glazed), labour, and VAT.

If you've done anything similar, please help me work out how much I need to save!

I believe you need planning permission to use a flat roof as a terrace. It usually overlooks neighbours. Our neighbours did this, another neighbour complained to council=no roof terrace.

You might also need to reinforce the roof. Sorry I have not helped with price.

Thanks Superram, knew about both of those issues. There are quite a few roof terraces round here (am in SW London) so enough local precedents to ensure planning will hopefully just be a formality.

Also know about the roof - in fact offering to pay my downstairs neighbour's share of the roof renewal is what persuaded her to let me go ahead with my plans .

So now I just need an idea of price - can anyone help me on this?

To nick through: between £1600-2300 at a rough guess.

This will get you a door hung too

*someone I know has just don't the same thing on a brick internal wall and cost £1500 approx.

Thanks Beaver. Ouch. More than I thought, by quite a long way .

If there is a window overlooking the flat roof, you could use that existing opening as the structural opening, allowing that the height of the lintel is correct for the required door. Or if it needs to be raised, you could technically re-use the existing lintel

You would also have to look at strengthening of the flat roof joists, as the load requirements for flat roofs and balconies (which this would be treated as) are quite different. This increased load would need to be followed down to the foundations and you'd need to check they are wide/deep enough for the proposed new load. You would also probably need planning permission for altering the elevation.

I'd suggest getting advice from a structural engineer or building surveyor.

I hadn't thought of re-using the lintel, that's a great idea.

At what stage should I get advice from a structural engineer? I know I'll need one, but was hoping that wouldn't be until I was ready to do the roof terrace itself.

Would it look very odd if I just left a space within the run of kitchen units, in readiness for the roof terrace knock through (which may not be for a couple of years)?

Depends how big your kitchen is, you could always put a moveable bench type unit there (like the ones in IKEA) as a temporary solution and some basic shelves above.

If you go to a company that do the whole package for you, ie planning, building control, building, then they will usually have their own engineers that they use regularly. If you want to get an opinion as to the feasibility of it, then the Institution of Structural Engineers have a database of practising Engineers

I'm a lapsed engineer