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Sewers, certificates, neighbours and timings: the parts of a London extension that nobody mentions until you are halfway in.
Do I need a build over agreement for my extension?
You need one if the extension will sit over, or within 3 metres of, a public sewer. On a London terrace that is common, because one shared sewer often runs across every back garden in the row. Ask the water company before the design is fixed.
Do I need a lawful development certificate for an extension?
It is not a legal requirement, but for a modular extension in London it is close to essential. It is the council's written confirmation that the extension is permitted development, it costs £274, and it protects you before the factory builds anything and when you come to sell.
How does the neighbour consultation scheme work?
It is the prior approval route for larger single-storey rear extensions. You tell the council what you plan, it writes to the adjoining neighbours, and if nobody raises a valid objection about their amenity, or the council does not decide within 42 days, you can build. The fee is £249.
Do I need a party wall agreement for a rear extension?
On a London terrace, almost always. Digging foundations within 3 metres of a neighbour's house, or building on or against the boundary wall, falls under the Party Wall etc. Act 1996. You serve notice; the neighbour either agrees in writing or a surveyor draws up an award.
Get a quote for your extension
Postcode, four quick questions, then your contact details. It takes about a minute.
We are an introduction service, not a builder. We look for a firm that works in your borough, tell you who it is, and pass your details on only when you say yes.
Got it. Thank you.
- We look for an extension builder who takes on jobs like yours in your part of London, and we email or phone you with the firm's name.
- If you are happy with that firm, we send it what you told us. If not, nothing goes anywhere.
- The firm arranges a visit, looks at the access and the ground, and gives you its price.