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  Good Repair Guide: Leaking basement walls

Residential basements are common in houses built on sloping ground and can be valuable and useful spaces if they are dry and warm. In many cases, the use of a basement changes over time as households sizes, lifestyle and interests change. 

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The environment that was acceptable when the basement was just a store for garden implements may no longer be good enough when a new purpose is planned. Work may be required to upgrade the space. High internal humidity, musty odours and efflorescence in below-grade basements are all signs that moisture may be entering the space through porous concrete retaining walls. 

This Good Practice Guide covers only basement walls of residential buildings on sloping sites that are no more than one story in height below natural ground and not subject to hydrostatic pressure. Where a wall is subject to hydrostatic pressure from groundwater or a spring, seek specific design advice from a specialist damp-proofing company.