Fact sheet
7 - 2011

Part 1: Tile adhesive quality and criteria for use

By Senior Researcher Arne Nesje, SINTEF. Commissioned by the Norwegian Building Ceramics Association

It is important to choose tile adhesive according to the strains the construction is exposed to. Shorter construction time has led to a development of tile adhesive and adhesives that are designed for quick progress and ability to absorb movements. Tile sizes have increased, from relatively small ceramic tiles to larger formats. Everything from small glass mosaic tiles to tile formats up to 600 x 1200 mm must be able to be mounted. The tile adhesive must also be easy to use. This variation in use requires several tile adhesive qualities with special properties. The increased use of tiles outdoors also requires frost resistant tiles for the Nordic climate. This article focuses on the right descriptions of tile adhesive and selecting tile adhesive for different purposes. The next article will talk about execution.

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Figure 1: The tile adhesive must be used for different purposes.

Terms, properties and requirements

The tile adhesive must be user-friendly, and at the same time have good strength and durability properties when it has dried out. Both Norwegian and foreign manufacturers must adhere to the common European standards concerning properties, classification and labelling. All packaging must be labelled and might look like e.g. figure 2.

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Figure 2: Example of labelling on the packaging.

How to select the right tile adhesive

If you are familiar with the classification and labelling system you will easily be able to see which properties, the tile adhesive has and if it is suitable for its intended use.
The tile adhesive must be user-friendly so that the tiler is able to mix the tile adhesive with water and work quickly. At the same time, it must have good strength and durability properties when it has set.
Table 1 shows the code system for classification and use.
The most commonly used tile adhesive type is cement-based tile adhesive (type C2). For special use, reaction resin adhesive (R) or dispersion tile adhesive (D) is used. Depending on usage there may be special requirements for:

  • bond under certain conditions, such as exposure to water, heat and frost
  • elasticity, i.e. ability to absorb movements between the tile and the surface
  • properties in wet condition
  • chemical resistance, e.g. the tile adhesive can be used in a dairy with a lot of chemicals or in chlorinated pool water
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ClassificationClass descriptions and requirementsUse
C1 Normal cement-based adhesive. Requirement: Bond strength >0.5 MPa On stable mineral foundations, e.g. older concrete floors with no heating cables. Rendered concrete- and clay walls
C2 Improved cement-based adhesive. Requirement: Bond strength >1.0 MPa Same use as for C1 and also: Fresh concrete foundations, concrete elements, LECA walls, concrete layers with heating cables, wet rooms and membranes, framewalls with boards, on old tiles
D1 Dispersion tile adhesive Dry wall areas
D2 Improved dispersion adhesive Dry wall areas that require high bond strength
R1 Reaction resin adhesive Areas exposed to chemicals aggressive to cement-based tile adhesive types og high strength is needed.
R2 Improved reaction resin adhesive
F Fast setting adhesive. Should obtain bond strength of min. 0.5 MPa after setting for 6 hours Same as C1 and C2 where short drying time is needed
T Adhesive with redused slip. The tile adhesive should move max. 0.5 mm on a vertical surface. The limit of non-sealable glue is 2 mm. Same as C1 and C2 on walls where you wish to lay tiles without support during the fixing process
E Tile adhesive with extended open time. Should be able to be adjusted up to 30 minutes after the tile adhesive has been applied to the surface, while a standard adhesive has an open time of 20 minutes. Same as C1 and C2 where fixing takes a long time
S1 Deformable adhesive. Should be able to tolerate at least 2.5 mm deflection in a deformation test according to NS-EN 12002 Fresh concrete underlayer, concrete elements, LECA walls, concrete layers with heating cables, wet rooms and membranes,framewalls with boards, on old tiles
S2 Highly deformable adhesive. Should be able to tolerate at least 5.0 mm deflection in a deformation test according to NS-EN 12002 On foundations with a risk of deflections or especially large cross motions

How to specify and describe the correct tile adhesive type

In work- and tender descriptions, e.g. after NS 3420- Specification texts for building, construction and installations which tile adhesive type is required must be specified. The more precise the description is, the better.

Experienced planners and professionals are quite familiar with which tile adhesive types are suitable for which uses. Many also turn to the manufacturer or the tile store directly to get some advice on choice of tile adhesive. Many tile stores have project divisions that work with advice on choice of tiles and tile adhesive. A description that is supposed to be put out to tender cannot contain the name of a specific manufacturer or type of tile adhesive; it must contain the tile adhesive group according to the table. Follow-up on the construction site is also important. There have been some problems with professionals that do not speak/read Norwegian and are therefore not familiar with our requirements and often have some trouble understanding the descriptions. That is why many of NBKFs Factsheets now is translated to English and Polish. Many tile adhesive manufacturers now also label their products in different languages. It is important that the workplace has routines for quality assurance that ensure that the descriptions are read and understood correctly.

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Figure 4: Larger tile works should be described according to NS3420 part N. Under section NH the tile adhesive type must be specified.
Figure 3: How to write a detailed description of the tile adhesive choice in NS-3420 codes
Tile adhesive type: Tile adhesive type ... (e.g. C2ES1, cement-based tile adhesive with improved contact and a long pot life (30 minutes open time)
Tile adhesive technique: One-sided application w/10 mm round trowels to achieve sufficient tile adhesive coverage
Tile adhesive thickness: ...mm
Tile adhesive use: ... kg/m2/mm thickness (according to the guidelines from the manufacturer)
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Figure 4a and b: Complete tile adhesive coverage and a sufficient thickness are requirements for successfully fixing tiles outdoors.

References

  • The book Alt om flislegging, SINTEF Byggforsk and BKF, 2011
  • NS-EN 12004 Tile adhesive for tiles
  • NS3420 Descriptive texts for building and construction

Image references: The NBKF image archive.