EWI is used in order to improve the thermal insulation performance or existing external walls.
EWI is the best way to insulate a solid wall property. EWI should be used only on walls that have not been affected by rising damp.
An EWI ‘system’ from PD Rendering is an insulation layer that’s attached to the wall’s exterior and then covered with a decorative and protective render, brick effect or other cladding finish.
The insulation layer may be expanded polystyrene EPS, phenolic or polyurethane board foam; or mineral wool (MWT) batts. A render coat is a cement-based or mineral- or synthetically-derived base coat that has been reinforced with mesh, and then covered with a primer. The top coat render then is applied. It can be smoothed, textured and painted or pebbledashed. Dry cladding may include timber boards and aluminium panels. Brick effect finishes, on the other hand, can be stone or clay tile or brick slips.
EWI provides many benefits including better protection of external walls from rain penetration and reduced heat loss.
Warmer walls decrease the possibility of condensation on internal walls and help with damp issues.
EWI will modify the exterior appearance of a home. Most times, planning permission or consent from the local council planning authority are required before any work can begin. EWI must adhere to the national Building Regulations. EWI’s ability to withstand fire may limit its placement and height.
Every property must be surveyed prior to installation. A wrong treatment can have a detrimental effect on the building fabric. Experts must conduct a condensation risk analysis where appropriate. If condensation will occur between insulation and walls, or between insulation and walls, a vapour barrier should be added between insulation and walls.
The existing wall type will determine the EWI that is best suited for your project. For example, solid rock walls might be breathable. This allows moisture to pass through the walls and evaporates away. It is possible to keep the wall’s breathability by using a breathable membrane insulation (MW) and an external render or other finish that is non-acrylic.
The walls of solid brick can be impermeable to moisture and non-breathable. Such walls can be made from rigid foam insulation.
In high humidity areas, window trickle fans and extract fans are required to provide room ventilation.
A high standard of installation is necessary for any property fabric work. Poor detailing e.g. Poor detailing, such as around the eaves allows water to pass behind insulation and can cause hidden damage to the property.
