# Common Extension Problems in London — and How to Avoid Them

Canonical URL: https://mirion.uk/blog/common-extension-problems-london/

> Extensions in London come with specific challenges — from Victorian foundations to party walls to drainage. Here are the most common problems and how we prevent them.

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Extensions in London come with specific challenges — from Victorian foundations to party walls to drainage. Here are the most common problems and how we prevent them.

*AI-generated illustration; not a completed Mirion project.* A small brick rear addition with a low dark roof, gutter, downpipe and glazed door.

## Extensions in London are not like extensions elsewhere

London properties — especially Victorian and Edwardian terraces — come with specific challenges. Here are the problems we see most often and how we prevent them.

## Unexpected ground conditions

**The problem:** London clay soil expands and contracts. Old properties often have shallow foundations.

**How we prevent it:** We carry out a ground survey before quoting.

## Drainage issues

**The problem:** Many older London properties have shared drainage near the extension footprint.

**How we prevent it:** We check drainage plans early and include any required approvals in the timeline.

## Party wall disputes

**The problem:** Extensions near shared walls need a party wall agreement.

**How we prevent it:** We advise on party wall requirements during the survey.

## Poor communication during the build

**The problem:** Many extension problems are communication problems.

**How we prevent it:** We give you a single point of contact throughout the project.

## The best extension is a well-planned one

Most extension problems are preventable with proper surveying, honest communication and realistic planning.