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Specifying External Wall Insulation

We understand that it can be a complex process specifying the most suitable external wall insulation system and that many factors can influence system choice and the decorative finish proposed.

Our technical representatives provide detailed design and technical assistance and with early engagement in the design process, we can advise on system selection and produce specifications that are closely tailored to the individual project requirements.

This provides opportunities for cost reductions associated with time and material waste whilst maximising value for money and maintaining the highest quality standards.

PermaRock offer systems based on a range of modern insulation materials that include firesafe mineral fibre, mineral fibre lamellaenhanced expanded polystyrene and high performance phenolic foam.

These systems have been designed to enable various methods of fixing to be employed, depending on the substrate condition and type i.e. blockwork/masonry/timber frame/lightweight metal frame/structural building systems.

When choosing a system, designers and specifiers must ensure that the following factors are taken into consideration to ensure the best solution for the project is adopted:

  • Type of Building/Wall Build-Up: system type should be chosen to suit the wall construction, type of building, design loads, and structural movement, etc.
  • Fire Performance: the system should be suitable for building use, low rise and/or high-rise application, as appropriate, and where required, should incorporate fire performance or fire-breaks to meet with Building Regulations and BR135 requirements.
  • Thermal Performance: what is the required U-value of the building envelope or SAP rating requirement? Are there limitations to the thickness (zone) of system which can be accommodated?
  • Aesthetics: is the desired type and colour of decorative finish available and suitable for the design and its intended location and exposure? 
  • Detailing and Interfaces: full consideration needs to be given to the interface with other materials and how the system is protected at edges, overhangs and abutments. 
  • Impact Resistance: the decorative finish may be selected primarily on the desired aesthetic appearance but must also take into consideration the level of impact resistance required. 
  • Cost: a number of design factors can have an effect on the cost of the system, including, insulation type and thickness as well as the selection of decorative finishes and fixing methods.
  • Exposure of Site: resistance to wind and impact loads, high/low traffic, local pollutants (e.g roads/ railways), etc. may need to be considered for system and finish selection.

All our systems are complimented by an extensive range of renders and decorative finishes including acrylic and silicone based textured renders, brick finishes and scratch renders.

PermaRock technical representatives are always on hand to assist and answer your queries, call them on 01509 262924 or email

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