How Much Can You Actually Add? Cockfosters Builders, EN4

We do not publish a rate per square metre. On the Green Belt edge the number that matters is not the size of the extension you want — it is the size of the extension you can have, and that varies enormously between two houses on the same road depending on what previous owners already used up.

So the sequence runs: establish the original building and the remaining allowance, confirm the conservation position, then design to what is achievable and price that. A written itemised scope, a fixed sum against it, contingency stated openly. Modest deposit, staged payments against completed work, balance at handover — never a large sum up front and never cash.

Through the build: one project manager, one programme, all trades ours, and drawings and structural calculations handled in house. Where a shared wall, a boundary wall or excavation near a neighbouring structure is involved, the Party Wall etc. Act 1996 applies and we serve and administer the notices. When the work is done: building control sign-off, the certificates and warranties handed over, snagging closed out rather than logged and forgotten, and a written workmanship guarantee. There are completed jobs in the gallery if you want to see the standard first.

We cover EN4 and the surrounding area — Cockfosters, Hadley Wood, Oakwood, East Barnet, New Barnet and Southgate.

Am I in the Green Belt, the conservation area, or both?

They are separate designations with separate tests and they overlap across Cockfosters. Green Belt asks whether your addition is disproportionate. Conservation asks whether it preserves character. A scheme can satisfy one and fail the other, which is why both need checking at the outset rather than sequentially.

How much has already been used up?

This is the question that decides most EN4 projects and the one homeowners rarely think to ask. Extensions built by previous owners count against the original building, so your starting allowance may be far smaller than the plot suggests. Establishing it takes historic records, not guesswork.

Can I go up instead of out?

Often the better route here. Loft conversions and roof alterations generally read as less harmful to Green Belt openness than building further into a garden, and the interwar semi-detached form suits hip-to-gable work particularly well. Worth testing before assuming an extension is the answer.

Start With the Numbers

Send us the address and an idea of what you want. We will establish the original building, work out what remains available, confirm the conservation and Green Belt position, and tell you honestly what is achievable — before you spend anything on design.

Call or email us and we will book a survey and put a fixed price together.