Laying methods

The laying or installation of tiles is the process by which ceramic tiles are anchored to floors or walls. The installation process must be performed with the utmost accuracy, as it will have beneficial effects both in terms of aesthetics and technical function.

The success of a good ceramic floor covering does not only depend from good quality of ceramic tiles. In fact, ceramic tiles are only the upper part of a multilayer system that includes substrate, bonding and grouting materials, expansion joints etc. For this reason the installation is as much important as the tiles themselves.

It's at this point that the ability of knowing how to combine aesthetics and appearance and technique, design and execution, request and result, comes into play. Interior designers and architects, but also tile layers and consumers, must therefore prepare a project which, besides giving indications of appearance, also contain rules to follow during laying operation; rules which change according to the particular character that is desired for the floor or wall.
The study of the floor covering should start at the very beginning according to the type of building, expected wear of the floor, expected static and dynamic weights the floor will have to stand etc.

The chromatic choices and the installation plans for a floor or wall must take into account various factors including the size of the space (height, natural or artificial lighting) as well as the laying patterns and style to be achieved.

The final result can vary due to optical effects perceived by the human eye caused by the colours and laying patterns.

For example, spaces of identical dimensions may seem different depending on how they are filled: black and dark colours reduce a space as they absorb light; white and light colours diffuse light and therefore enlarge a space; vertical lines make a space look higher while horizontal lines make it look wider. Square patterns make a space look higher and wider.

Black or dark surfaces seem smaller than white or light ones of the same size. Instead, an uniform light coloured floor visually makes a room seem larger and is particularly indicated for small rooms while contrasting tones reduce the perceived dimension. A contrasting floor-wall combination guarantees a wider perception of a room compared to its true size so this solution is particularly suitable for bathrooms and corridors.

Design is an essential preliminary phase for the realization of a correctly covered surface.

For good laying design it is necessary to analyze the characteristics of the surface to be tiled. These are critical for establishing the correct design solution and the appropriate laying methods; this analysis in fact influences and determines the correct project solution to be adopted:

•   the condition of the surfaces, an examination of the surfaces makes it possible to establish if cleaning treatments are necessary and to choose the most suitable adhesive;

•   the dilatometric behaviour, which may lead to stresses due to the expansion of certain layers;

•   the modulus of elasticity and sizing, which determine the behaviour of the structure under real load conditions;

•  the composition and structural arrangement, which indicates the location and dimension of construction joints, allowing for some movements between close parts in the structure;

• the geometry of the surface to be tiled, which may affect the choice of tiles, their layout and the tile laying technique.

The realization of the joints requires particular care: the aesthetic, technical and economic value of the tiled surface depends on them and so nothing can be left to chance and also the type of filling material has to be established: the joint’s width should also be assessed carefully as only a few millimetres may result in very different visual impacts and a joint is filled with unsuitable material or an imprecise application of the binding agents may in fact ruin the entire work.

For floor tiles laid with a combination of different rectified sizes, a 2 mm joint is necessary. For layouts with a combination of non-rectified rustic materials, a 4 mm joint is necessary. For wall coverings laid using a rectified product, a 2 mm joint is necessary. Tile installation without joints (closed joints) is cheaper and faster, but has the disadvantage of making floors more rigid and unable to withstand mechanical shocks. During the last few years, many major tile manufacturers have begun manufacturing special fillers to colour and protect joints.

The quality and durability of a tiled surface depend on the laying methods used during its creation. The operations to carry out vary depending on the techniques applied.  The installation bed that anchors the tiles to the floor may be made of cement-mortar (mortar fixing) or special bonding agents (adhesive fixing). The binding layer or bedding may be composed of two different materials: the cement mortar and the adhesives.

With cement mortar laying, mixtures of cement (and/or lime), sand and water are used.
The mortar, applied in a "thick bed" (3-5 cm), forms a binding layer endowed with: good mechanical resistance, high rigidity, adequate adhesiveness, resistance to frost, and moderate resistance to chemical attack.

Adhesive fixing is a finer, more accurate and expensive installation technique; in fact, in addition to the costs for the bonding agents this installation method requires the intended laying surface to be properly prepared in order to obtain a perfectly horizontal layer of cement called concrete slab. 

The adhesives to use for laying may be cement- and organic-based.
The first are essentially pre-dosed cement mortars enriched with additives, which increase their ability to retain water. They are particularly suitable for being used in thin layers, and are not recommended for very flexible structures. The organic-based adhesives are of two types: adhesives dispersed in water and reactive resin-based adhesives. The first have good flexibility properties, but their field of application is limited to interior wall coverings; reactive resins-based adhesives are recommended for environments and working conditions which require special chemical and mechanical properties of the tiling.

Quite often tiles that are laid together have the same sizes, however there are also installation techniques that combine tiles of different dimensions and shapes. Joints between tiles can also follow different directions and create many different decorative patterns.

The most common tile installation designs are:

• parallel installation

• diagonal installation

• straight-forward layout: type with rectangular shapes, a 3 mm joint is necessary. This also requires special attention in combining and levelling the single pieces so as to reduce the differences in flatness that may be present.

• herringbone pattern

• diagonal installation with inset tile

A well laid surface should be perfectly flat with accurate and straight joints. 
It is important to avoid walking on the floor for 2/3 days time to allow proper curing of the multilayer system. When using the cement mortar system without curing additives it is necessary to wait even for one month before stressing the floor with weights. Recent technological advances produced tiles with advanced features able to satisfy the needs of many different types of environments and complex architectural structures, consequently also laying methods have developed in the same way.

For larger areas, or for surfaces affected by significant thermal shocks it could be useful to use expansion joints to relieve stress and prevent cracking. In case of large areas, it is necessary to foresee at regular distance the installation of expansion joints to absorb floor movements that would generate tiles cracks. In smaller areas it is sufficient to leave a small gap close to the walls and the installation of bullnoses and/or coved skirtings will then cover this gap and complete the aesthetic of tiling work.

In work environments where cable installations (IT networks, electricity, telephone lines, etc) are required, useful solutions are floating floors (or raised floors), i.e. advanced flooring systems where tiles are laid on removable panels raised from the ground thanks to special supporting structures.

In modern-day architecture designs ventilated walls are also becoming very popular, they consists of a wall covering system where tiles are not bond to the wall to be covered and leave an air gap that a generates significant advantages in terms of thermal energy savings.

The durability of a tiled floor and wall also depends on the attention and care given to it: a well-laying tiling will retain its quality and aesthetic characteristics over time thanks also to proper use and correct maintenance.