Closed cell foam can be applied in two different manners; spray application and slow pour formats. When insulating between the exterior walls of a house, the slow pour method is used. As its name implies, it is poured slowly, it gets into every nook and gap and is designed to adhere to the inner and outer blocks thus creating an airtight and waterproof barrier. This method is also ideal when an older house was constructed with no insulation between the two block walls.
Traditionally, rigid boards or polybeads were used to insulate, however, these systems do not offer the airtightness that is achieved with foam nor do they compare with the insulating qualities of spray foam. The application of closed cell foam, because of its high density, results in an airtight, waterproof barrier and achieves the high u-value requirements all in one application.
It also restores the structural stability of older builds where mortar, brick or stone have degraded or where the conventional wall ties have corroded. By creating this water tight membrane, it has excellent resistance to driving wind and rain ultimately reducing air leakage from the external environment to to zero.
It is quick and easy to apply with a minimal amount of disturbance and mess and can usually be completed within a day.
Basically, holes are drilled in the external wall at certain intervals. The spray foam is then introduced into these holes creating the airtight seal. This process is continued horizontally and upwards of the walls until the entire structure is insulated.
Spray foam insulation can also be applied as a “Partial Fill” where there is existing insulation within a cavity wall. Often when polystyrene boards are used to insulate a home they are ill fitted and a residual cavity ranging in thicknesses from 25mm to 50mm exists. This, of course, reduces the overall U-Value. Spray foam insulation can be injected into this cavity filling all spaces thereby creating an airtight, more energy efficient, watertight insulation layer which dramatically increases the heat resistance of the wall.