Frequently Asked Questions: External Wall Insulation

Generally, cement based materials can be applied between 5°C and 30°C. Freshly applied materials should be protected from excessive temperature (either very low or very high), direct rain and rapid drying conditions. Common to all cementitious materials, inclement weather or long periods of dampness will encourage the phenomenon of efflorescence (commonly know as lime bloom).

Many of our external wall systems are suitable for use above 11 metres as stated within Building Regulation Approved Document B and Scotland’s Technical Handbook and have achieved a reaction to fire classification of A2-s1,d0 in accordance with BS EN13501-1.

It would be the responsibility of the projects design team to ensure any construction or renovations meet the building regulations. 

All of our external wall insulation systems have been tested for reaction to fire to obtain a classification in accordance with BS EN13501-1. 

Use the buttons below to view our systems by their reaction to fire classifications:

A2-s1,d0 B-s1,d0 B-s2,d0

A specification should provide performance characteristics of the system for the design team to determine its suitability for the project. The specification is also commonly used for project costing at tender and construction stages forming part of the contractual documents, helping minimise project risk if there are any disputes in the future.

If you have any questions regarding our external wall insulation solutions from Weber please feel free to get in touch with us:

Find your local Weber contact → Contact us →

Our systems are available with a choice of different insulation board types.

The thickness of the insulation board will impact the level of thermal performance the chosen external wall insulation system can provide.

The target U-value will determine what thickness of board is required. You can use our U-value Estimator tool to explore options or get in touch with us.

The number of fixings depends on the substrate and the fixing methodology of the chosen system. See relevant specification sheet.

The depth of the fixings is dependant on the substrate and the required pull out load. Contact our technical team for advice quoting the project name and address.

If using webertherm EPS, a spiral fixing can be used. Each fixing can hold approx. 5kg. Ensure there is a tight mastic seal in place to prevent water ingress.

Alternatively, there is an ISO-Dart fixing available to fix medium to heavy objects when using webertherm EPS or webertherm MFD. Unlike the spiral fixing, this fixing penetrates the substrate, again please ensure that a suitable mastic sealant is used after.

Our external wall insulation systems with BBA certification may be suitable on Government funded schemes, although it is more common that the system needs to achieve an A2-s1,d0 reaction to fire classification in accordance with BS EN13501-1. It is also required that a 3rd Party insurance guarantee is required for installation and materials used for this type of work.  

Quotes for both the system and the insulation can be obtained from applicators:

Find a contractor → Find your local Weber specification manager →

Our external wall insulation systems should only be installed by a reputable specialist external wall insulation applicators who have successfully undergone product training and registration by the Certificate holder (Weber), this is a requirement of our BBA certification and guarantee.

Find a contractor → Find your local Weber contact →

Yes - please consult your Operating & Maintenance manual. 

Yes, our webertherm XM panel systems with mineral fibre insulation are best suited for framed structures and have BBA certification for this type of construction.

In addition, our specification team will need to ensure suitability by performing a condensation risk analysis. Please refer to the webertherm XM BBA certificate (Product Sheet 6) for more information, or contact us.

Weber can work out the U-value and condensation risk for you based on the whole wall build-up.

You can use our U-Value Estimator but a full analysis is recommended. Please contact our technical team for more information.