What will I have on my walls?
In all cases, Greenhus aims to improve the thermal performance of your walls to the equivalent of a new-build, i.e. with a u-value of 0.3 W/m2K. (See our section on heat loss for a simple understanding of u-values). We achieve this thanks to the heart of the system – the insulation board.
This is either Expanded Polystyrene (EPS) or Mineral Wool. With most wall constructions, we will need to use a 90mm thick EPS insulation board or a 120mm thick mineral wool board to achieve the desired thermal performance. (Mineral Wool does not have such good insulating properties, so a greater thickness is required to achieve the same thermal improvement.)
How long will it last?
Greenhus uses only BBA-accredited systems, which are required to demonstrate a 25-year life expectancy. (The earliest example of External Wall Insulation that still performs as installed dates back to 1957, so you can be confident of at least 25 years.) As the system uses inert products that won’t interact with the environment, there is no reason why your installation should not give decades of trouble-free benefits.
How thick will my system be?
To achieve our target thermal improvement and reduce your wall u-value to 0.3 W/m2K, Greenhus will typically apply 90mm of EPS or 120mm of Mineral Wool. In each case, the associated layers will add further thickness. With EPS, there will an additional 12mm (approx.) and for Mineral Wool there will be an additional 15mm (approx.).
The rule is:
EPS total thickness = Insulation board + 12mm (so 102mm/4” in most applications)
Mineral Wool total thickness = insulation board + 15mm (so 135mm/5.5” in most applications)
How will this affect my window sills and other fixtures?
At Greenhus, we take a “whole property” approach and will amend all your external features to accommodate the increased wall thickness. This will involve extended window sills and the extension/re-routing of wall-mounted pipework.
How is it installed?
You can find a full step-by-step description here, including actual photographs of Greenhus installations.
System detail – What is EPS?
EPS foam is a rigid, tough, close-cell foam. It is made using solid beads of polystyrene which are then expanded during production to form perfectly-closed cells. The production process increases the volume of the cells by up to 50 times. Once cooled, the foam can be cut or shaped depending on its intended use, in our case for External Wall Insulation boards.
It’s important that the boards are dimensionally stable for use in EWI – we don’t want movement. To achieve this, the manufacturing process includes processes to age and cure the boards.
When used for External Wall Insulation, boards can be supplied in thicknesses of between 20mm and 380mm. The thicker the board, the greater the insulating qualities. We will recommend the necessary thickness as part of our free quotation service.
- Close-cell foam insulation board
- Inert and non-toxic
- Does not contain Chlorofluorocarbons (CFCs) or Hydrofluorocarbons (HCFCs)
- 100% recyclable
- Global Warming Potential < 5
- Thermal conductivity (K-value) of 0.030 W/mK (use this value as a comparison with other insulation products)