Internal Wall Insulation (IWI)

When we think of wall insulation we generally think of cavity wall insulation which is no solution for the many solid wall properties in the UK. Insulating the internal walls could make a big impact on annual heating bills. According to the Energy Savings Trust this could save up to £650 on annual heating bills. If your property is built before the 1930’s highly likely to be a solid wall property.

It’s common knowledge that solid wall properties perform less favourably to cavity wall properties even when a cavity wall in unfiled. The countries grant schemes have focussed heavily on cavity walls being insulated in the based which has neglected the hardest to heat homes. The most expensive to heat properties in the UK have no access to main gas and are generally heated either by electric, solid fuels, LPG or Oil. Now focussing on the hard to heat homes grants are available and are financially viable on all off-gas properties. Although also available to on gas properties large customer contributions would be required to cover the installation costs.

For solid wall homes they can be insulated either externally or internally, whilst both perform with similar heat retention and savings, although the cost of external wall insulation is significantly higher which comes at the cost of losing the original external character of the building. The installation also required scaffolding and is weather dependant which in the UK can result in long delays and inconvenience

Internal Wall Insulation, by comparison, is a more cost effective option where the install is more straight forward and items such as kitchen units, radiators and electrics can be removed and reinstated once the walls have been insulated give the property a free new look internally. Installing a Damp Course behind the insulation can also protect the interior of the property from future risks of penetrative damp

Internal Wall Insulation involves the application of insulation board to the interior face of external walls to improve the thermal performance of the building.

Current building regulations require all new build properties to achieve a U-Value (rate at which heat is lost) a maximum of 0.3W/m² and realistically 0.2W/m. Please Note the lower the U-Value the better. In comparison an uninsulated Solid Brick property 225mm wide has a U-Value of 1.9W/m². To Achieve this a dense high performance insulation board is required to be fitted

It has been well established that improving airtightness has a greater impact on heat loss than insulation. The solid elements of the wall will naturally be fairly airtight — but it is the gaps, cracks and penetrations that can be problematic. These tend to occur as much in awkward places floor/ceiling voids, below the ground floor, the first floor ceiling“ as on the accessible areas of the wall. The insulation applied to the wall can form the airtight barrier, but the benefit will be reduced by up to 50 per cent if the gaps, cracks and penetrations are not also dealt with.