External Solid Wall Insulation
Circa 35% of heat is lost through external walls.
Our preference is to insulate walls externally. The reasons are because your solid walls are an excellent thermal store of energy when insulated externally, air tightness can be controlled, thermal bridging is virtually eliminated, there will be less disruption to your family, and the internal area of rooms is not reduced. However, external wall insulation cannot always be used due to Local Authority restrictions. In such cases, you would need to insulate internally.
External wall insulation consists of a water proof insulation layer which is mechanically fixed to the outside face of an external wall. Various flashing and water proof details are fixed at the junctions with other surfaces such as the roof, window reveals and at ground level.
The insulation layer is usually 100mm thick, but it can be up to 300mm thick, dependent on the required thermal performance. The completed installation is usually has a rendered finish. Systems are also available should you require other finishes e.g. brick slips, timber cladding or tiles hung horizontally. Some homes are finished with a combination e.g. brick slips to the ground floor, render to the first floor.
External wall insulation causes little disruption to the occupants of the home, but can be more expensive than cavity or internal wall insulation.
Typical costs are in the region of £9,400-£13,000, giving annual savings of £475. The payback period is up to 27 years, with annual carbon savings of 1.9 tonnes*.
If you would like to view the blog on the green conversion and renovation of a Victorian London apartment, click here
*Energy Saving Trust 2011.