Industry experts put forward case studies where installations have failed due to the incorrect usage of adhesives and sealants.

Too often a floor fails due to poor adhesive and sealant applications. To find out why, and how these can be prevented, we turned to some of the industry experts. Here they share their experiences, identifying the numerous challenges that they were called in to resolve, along with invaluable advice that aims to minimise the risk of similar failures occurring in future projects.

Alistair Mac Dougall, Sales Manager at ITE Products

1.    After being called in for assistance, what did you observe?
We were asked to determine the cause of Luxury Vinyl Planks peaking (starting to lift) in the reception area of a corporate head office.

Upon inspection, it was immediately apparent that the peaking was not consistent in all areas as certain parts of the floor remained unaffected. The worst affected area was in front of the large glass windows, on the North side of the entrance foyer, while planks in front of the concrete stairs were also peaking. The peaking in both areas occurred predominantly at the ends of the planks.

The sunlight reflected roughly one metre into the room and onto the floor. As would be expected, the flooring exposed to direct sunlight was considerably hotter than the flooring installed further into the room.

When tested with an infra-red thermometer, the temperature of the floor exposed to direct sunlight measured at 48°C, while the reading in the shaded area was 23°C.

There was also evidence of rainwater pooling against sections of the glass façade. We lifted a plank against the window and immediately observed moisture droplets under the plank. The adhesive was slimy, and had a distinct odour of mould. The screed was dark grey in colour. Our first conclusion was that moisture played a key role in this instance. A moisture test confirmed that the moisture content of the screed exceeded 6%. At the staircase, the screed revealed a moisture content of 4,2%.

We consulted with the flooring contactor to ascertain the screed moisture content prior to installation. His response was that he had carried out tests using liquid droplets and the results had shown that the screed was indeed dry. He stated that he had used an adhesive which was cheaper than the recommended one, but that he had never experienced any problems with this specific adhesive before. His team had carried out several similar installations without any problems.

2.    What solution/s did you provide?
The cause of failure was a combination of factors that doomed the project. The adhesive failed because it was not able to cope with:
1.    The high moisture levels;
2.    It was unable to prevent dimensional change with the direct sunlight falling on it.
The only remedy was to uplift the flooring, remove all traces of adhesive, apply a moisture barrier, apply a self-levelling compound and install the flooring using the correct adhesive. In addition, the windows where the direct sunlight was falling needed to be fitted with blinds, or a solar screen laminate.

3.    How could such a failure be prevented in future?
When installing LVT’s in particular, the adhesive plays a crucial role in a successful installation. The installation can only be successful when the adhesive is given the best chance of success by ensuring that all contributory factors are taken care of.

These include:
1.    The maximum screed moisture content as specified by the flooring manufacturer needs to be adhered to.
2.    The use of suitable, accurate moisture reading equipment and ensuring it is correctly used.
3.    Ensuring that the flooring is given enough time to acclimatise to the conditions it will be subjected to prior to installation.
4.    Ensuring that environmental factors that may affect conditions (such as direct sunlight) are catered for.
5.    That screed conditions are in accordance with the requirements.
6.    That only the recommended adhesives are used in the installation.
7.    That the correct tools are used in the installation.
8.    That all the recommended practices are followed in the installation.

The choice of adhesive is paramount. It has to be fit for purpose and non-recommended adhesives are exactly that, for a reason. It is important to remember that specialised adhesives form part of a system, which is why you should familiarise yourself with the system and follow it to the letter. It is important to note that even though the adhesive is a small part of the installation cost, failure as a result of using non-recommended adhesives is extremely costly, foolish and unnecessary.

Sharon Margon, Technical Advice Supervisor at TAL

1.    After being called in for assistance, what did you observe?
We were asked to investigate the cause of the hollow-sounding and loose floor tiles at a commercial office park.

Upon inspection, we noted that the 600 x 600mm porcelain tiles had been installed onto exterior surface beds on the walkways, courtyards and building entrances. A significant number of tiles were hollow-sounding and tiles had delaminated (lifted) in areas. Extensive cracking was also noted in the grout joints; and sections of grout had ‘popped’ out of the joints.

Although intermediate tile panel movement joints had been created in the tile installations, these were located at approximately five metre centres, and not the three metre centres required for external installations. Furthermore, in areas where tile panel movement joints had been created, the majority of these joints were superficial. This means that the joint sealant material did not extend through the tile and tile adhesive layers to the substrate. The perimeter joints against the building entrances and planter boxes had been filled with a cementitious grout, and not a resilient joint sealant.

We were unable to establish whether a high-strength rapid- or quick-setting adhesive had been used, as required when installing vitrified tiles such as porcelain tiles, or whether a latex-additive had been incorporated in the adhesive and grout mix to allow for the building and thermal movements associated with external installations.

2.    What solution/s did you provide?
Based on our observations, the installation failure occurred due to insufficient allowance for movement in the tile installation. This would have been compounded by not using a latex-modified adhesive and grout system.

When tile installation failures occur, they are usually caused by a number of contributing factors, rather than one single factor. However, more often than not, the lack of, or incorrectly constructed, intermediate tile panel movement joints is the major contributing factor.

Tile panel movement joints and perimeter joints in tile installations cater for the anticipated structural, background and thermal movements. These joints are specifically constructed to ensure no compressive stress builds up and subsequent unnecessary forces are projected on the adhesive and tile.  

All external installations will be exposed to building movement, thermal expansion and contraction, as well as inclement weather conditions (rain, dew, frost, etc.), and therefore require a far stronger and more flexible adhesive and grout system to cater for these conditions. TAL Bond or TAL Bond Powder must be incorporated in the adhesive and grout mix in accordance with the manufacturer’s instructions.

It is our experience that, once an installation failure of this nature occurs, it is likely that the entire tile installation will eventually fail.  It was therefore recommended that the remedial tiling should include the entire area.

A specification was issued for retiling, summarised as follows:

•    Tiles to be installed using a rapid-setting high-strength adhesive (TAL Goldstar 6) suitable for use with vitrified tiles, such as porcelain tiles, to ensure a solid bed of adhesive beneath each tile.
•    The tile adhesive and tile grout to be mixed with a latex additive (TAL Bond), as a total water replacement, for enhanced bond strength, flexibility and water resistance.
•    Correctly constructed intermediate tile panel movement joints to be created at maximum three metre centres in both directions to allow for anticipated building and thermal movements, as well as around the perimeter of the floors and around all fixtures protruding through the installation such as columns, walls and stairs.
•    All construction/structural joints and saw cut joints in the substrate to be respected and maintained in the tile installation.

3.    How could such a failure be prevented in future?
For any project, commercial or residential, it is essential that all of the various factors be taken into consideration at the project design stage.

Factors which must be taken into consideration include:
•    Substrate curing times;
•    Surface preparation (such as the priming of smooth and dense surfaces);
•    The use of the correct adhesive and grout systems; these must cater not only for the selected tile, but also for the traffic conditions, expected movement and other extraneous factors that can adversely affect an installation; and  
•    The location of tile panel movement joints.

A project-specific detailed materials and methods specification should be obtained prior to tiling.  This comprehensive document will include complete technical instructions on background preparation, adhesive and grout systems as well as the location of tile panel movement joints.

Michael Berg, National Sales & Marketing Manager at Den Braven

Michael offers four key insights with regards to sealant selection, what factors need to be considered when deciding on a sealant, and how sealant failures could be prevented in future.

1.    What needs to be taken into consideration when selecting a sealant?
The choice and use of a correct sealant for a particular application is very important. Unfortunately, sealant specification is neglected in most cases leading to failures with costly implications. There are various factors that need to be considered when making a choice of a suitable sealant. These can either be Silicones, Hybrids (Spur and MS), Polyurethane, Acrylics and solvent based non filled S-EB-S sealants.

The following 12 factors need to be taken into account when considering sealants:
•    The type of joint
•    Chemical resistance
•    Durability and weatherability
•    UV and ozone resistance and stability
•    Fungicide and bactericide
•    Guarantees and warranties
•    Certifications
•    TVOC (Total volatile organic compounds)
•    Correct surface preparations
•    Surfaces and substrates
•    Compatibility
•    Movement capability

2.    Which sealants would you recommend and why?
Unfortunately one is called when problems have already occurred. As a rule, polyurethane sealants are more susceptible to bubbling than other types of sealants due to the chemical composition of the product (namely the release of carbon dioxide during the polymerisation). This gas can form bubbles in the sealant when applied in wet conditions, or when application temperatures are high.

We would recommend Hybriflex 540, a SPUR product as the alternative. It has a particular formulation based on a technology that avoids the formation of carbon dioxide in the sealant while curing.

3.    How could such a failure be prevented in future?
Sealant failures, be it bubbling, adhesion failures, cohesive failures, or even non compatibility on certain substrates i.e. natural stone, laminated glass or mirrors can be avoided by consulting with our technical representatives or by referring to the technical datasheets. It is also important to insist on several international quality norms and test standards.

4.    What products would you recommend to a client and why?
Den Braven would recommend that the correct sealant technology be considered for the application at hand. We offer a range of high grade sealants, complete with a quality assurance programme and onsite training on how to correctly use these products.

What becomes very evident from the expert opinions above is that quality is a must, as is the condition of the substrate or material onto which the sealant or adhesive will be applied. Several critical factors are highlighted that need to be taken into consideration before acquiring a sealant and adhesive, and we strongly advise that these guidelines be followed in order to prevent unnecessary challenges or failures.