What is it?

A method of finishing the external envelope of a building to:

• Meet the Building Regulations for the external wall
• Achieve higher levels of insulation value in the external wall and dramatically reduce heat loss
• Achieve high levels of acoustic performance
• Achieve low fluctuations in internal temperature
• Create a heat store in the external fabric thus eliminating problems associated with cold bridging
• Provide protection to the structure using High Polymer or Silicone based render finishes
• Allow for the implementation of complex design arrangements and allow for design freedom in aesthetics and colour choice
• Be innovative
• Allow for fast track construction
• Add value to the building

Insulation Type Selection

Typically the following insulation mediums are used in the UK marketplace for EWI:

• Mineral Wool 0.036 W/M2K
• Polystyrene 0.036 W/M2K
• Cork 0.034 W/M2K
• Pheonolic 0.022W/M2K
• Urethane 0.027 W/M2K

Invariably in new build applications EPS and mineral wool are the most common specified insulation types as these are used with lightweight thin coat renders with silicone finishes. In this market Cork is offered as an alternative where environmental considerations are paramount.

Phenolic and Urethane insulation mediums are much more used in social Housing where the thickness of the insulation must be kept to a minimum without impacting on thermal performance. A range of finishes can be applied to these boards.

Specification Issues

In determining the correct system specification for EWI the following factors should be considered:

• Insulation Type - Mineral Wool , EPS, Cork, Urethane and Phenolic.
• Adhesive Coat - Acrylic, High Polymer
• Reinforcement - Glassfibre, Heavy duty glassfibre , Stainless steel lath.
• Choice of finish - Silicone/ Acryllic self coloured, brick effect render, brick slips , scratch plaster, smooth finish and dry dash finish.
• Supporting medium - monolithic(masonary), NHBC drained cavity, structural rail support (nontraditional housing)
• Lifecycle support - warranty options available.
• Cost - accurate budget cost predictions as system build up affects cost.

The above issues are not exhaustive and good technical advice should always be sought prior to specifying external wall insulation.

SYKES Specialist Contracting Ltd has vast knowledge in the systems available in the Uk and can provide impartial advice on system selection ensuring that the system selected is fit for purpose .