In certain areas of the UK it is best advice to insulate a cavity wall from the outside using an exterior insulated render system as opposed to in-filling the cavity.
The map opposite represents the official British Standard Wind Driven Rain Index with the darkest blue sections showing areas in which homes should not be cavity insulated due to wind-driven rain causing damp.
The areas coloured yellow and the lightest blue are suitable for cavity insulation and those coloured purple and deep blue are deemed unsuitable.
The medium blue areas such as Cornwall,Devon and Dorset signify homes that can be safely cavity insulated but only if they are sheltered from driving rain.
What Are The Risks ?
Originally cavity walls were used in areas at risk of wind driven rain to prevent water penetrating through to the inside by creating an air gap between two walls.
In seeking to cut heat loss and lower heating bills you should not in-fill these cavities as it creates a bridge for water to pass across to the inside and cause damp patches.
Advice, Quotes & Grants
If your home is in one of the risk areas and you would like to find out more information on externally insulating these walls, get in touch. We offer sound advice,free no- obligation quotes and in some instances can even get you a grant to help towards the costs.