FAQs

External Wall Insulation

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.

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.

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.

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

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.

Different external wall insulation systems have different finishes and colours available, see all colour charts for external wall insulation systems.

Our external wall insulation systems can be finished in a range of textures and finishes – it is also worth noting that scraped texture systems can also be detailed with ashlar and quoins.

Use the buttons below to explore systems for each:

Scraped Roughcast Dry dash Textured finish Brick-effect

 

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 specification manager →

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).

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.

Yes - please consult your Operating & Maintenance manual. 

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 →

Renders & Decorative Finishes

All product and system datasheets are available from our Download Centre.

Minimum temperature: 5°C – anything lower increases the possibility of water freezing may cause problems such as cracking and debonding of the render. 

Read our guide on working in cold weather →.

Maximum temperature: 30°C – anything higher and the render would need to be applied in shaded areas and the substrate may need cooling with a mist spray of water. 

Read our guide on hot weather working → 

Product coverage varies between products and the thickness it is applied. Information on coverage is found on:

  • Each product or system page on our website
  • Each product or system datasheet, which can be found in our Download Centre.

Weep holes are a standard architectural detail and are required as instructed by the architect.

Not directly, render will not bond to a previously painted surface so you will need to either remove the paint or consider a decorative coating or an external wall insulation solution.

Read our guide on rendering over painted backgrounds →

Yes. You will need to create a cavity between the main frame and the panel being rendered — see NHBC or TRADA website for details of this.  The render system weberend MT can then be applied to a suitable render board.

We do not have a designated block manufactuer, but the type of blocks used is important. 

Typically, a medium-density (1350–1450kg/m³, 3.6–7.3kN), general purpose, concrete block with a mortar cement:lime:sand ratio of 1:1:6 will satisfy these requirements. 

Movement joints are required by the substrate and should be followed through the render. Details of where movement joints are required can be obtained from the relevant codes of practice for masonry construction. If in doubt, advice from a structural engineer should be sought.

More information can be found in our Best Practice Guide

Yes. We have a BBA Certificate for weberpral M and NSAI Certificate for weberpral D.

Lime bloom is a natural phenomenon in cement/lime based products and is neither an application or product fault. For more details on causes and remedial action.

Take a look at our guide on lime bloom →

Straight line cracking is not typical of render failure, but rather of the reflection in the render of a crack in the substrate. For more information and suitable remedial action.

Read our guide on repairing cracks in externally rendered walls →

The date on the bag is the manufacture date. The shelf life will be on the bag and for most products is 12 months.

Tile Fixing Products

BS5385:1 states that wooden substrates are no longer suitable to tile directly to, therefore it would be advised to use a tile backer board.

Consumption calculators can be found on all of our product pages on our website. However, an approximate calculation can be obtained by this equation: 1.7kg x mm x m² and dividing by 25 — alternatively, use the Consumption Calculator on the weberfloor flex product page.

No, weberfloor flex is formulated with selected products and should not have anything added to it other than 5 litres of clean water.

Quartz tiles require a highly flexible adhesive. The ideal option is to use weberset plus with weber AD250, weberset pro lite - rapid can also be used if tiling onto floors.

weberset plus requires the use of weber AD250 admixture to be used for underfloor heating or under-tile warming.

This is dependant on the substrate, typically from a dilution you should get 0.2L/m² — this information can be found on the back of the packaging.

Ready mixed tile adhesives are for use on wall tiling only. The maximum tile size would be 30x30cm ceramic only, small porcelain can be used but precautions should be taken.

Plasterboard can take up to 32kg/m² for direct fix and if it is skimmed then this reduced to 20kg/m². Please allow 3.5kg/m² for adhesive and grout.

If you are using a cement based tile adhesive, please use weber PR360 to prime the walls first.

The appropriate PPE should be worn at all times when mixing and applying all materials, Low Dust Technology™ reduces the dust cloud, but there will still be some airborne particles so it is advised to wear a suitable dust mask.

Find out more about Low Dust Technology™ →

Flooring Systems

weberfloor 4310 (and rapid-setting alternative, weberfloor 4320) are the two main products to use with underfloor heating and in most circumstances you would need to cover the pipes by at least 15mm.

Please consult with our technical team for other applications.

At least 2 coats of primer are required. Primer must be applied by brush as opposed to roller or spray application.

All the datasheets for the products can be found by either visiting the relevant product page, or by searching in our Download Centre.

For normal drying products, follow the guidance of the manufacture of the adhesive/floor covering. This will generally require the floor to be below 75% relative humidity.  

The shelf life should be on the datasheet and the packaging. For most products, the shelf life is 12 months.

No, the date on the bags is the manufacture date.

Refer to the datasheet information. A flow table and ring should be used for machine mixing.

No, never add more water than recommended or try to re-mix material after its pot life.

Technical Mortars

Minimum: Any material that requires water should not be used where there is a possibility of the water freezing before initial hydration of the cement has taken place. BS 8000 states that 5°C is the minimum temperature at which cementitious materials should be used.

Maximum: The maximum temperature at which Weber recommends the use of its products is 30°C. If using above these temperatures please contact our technical department on 08703 330070 or by emailing technical@netweber.co.uk  

The actual minimum and maximum temperature at which each of our products can be applied are detailed in the datasheets at the Download Centre.

Product coverage varies between products and the thickness it is applied. Information on coverage is found on:

  • Each product or system page on our website
  • Each product or system datasheet, which can be found in our Download Centre.

All the relevant mechanical data for our products are outlined on the data sheet in the Download Centre. For more specific information please email technical@netweber.co.uk

Minimum and maximum thickness of application is detailed on the relevant data sheets in the Download Centre. For special requirements please email technical@netweber.co.uk

Click Compare to help you choose the right product for your project, if you need further assistance please email technical@netweber.co.uk

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