Don't let drains put a stop to your extension plans – take note of the 6 things experts want you to know in order to ensure a smooth-running project

Process of building an extension to a older white rendered house.

Are you planning on adding an extension over where a drain sits? Don't, in all the excitement of planning your new space, neglect to take into account the less glamourous aspects of the project – including how it will affect existing services, like your drains.

Building an extension can throw up all kinds of unexpected issues, be that a planning constraint you weren't previously aware of, unsuitable ground conditions or the need for a Party Wall Agreement. Being aware of these 'hidden' complications early on means no pesky delays or the need to unexpectedly spend more than you had budgeted for.