Tile Materials, Selection, and Storage

Tile Materials, Selection, and Storage

Chapter Introduction

This chapter covers all the knowledge required by the Tilesetter Apprenticeship Program for the Red Seal exam. Mastering materials — their properties, classification, compatibility, and storage — is fundamental. A mistake in selection or storage compromises the integrity of the installation, even if the setting is technically perfect. This chapter prepares you to identify, specify, and protect materials according to applicable Canadian standards.

Classification of Ceramic Tiles

Ceramic Tiles versus Porcelain

The main distinction is based on the water absorption rate and the manufacturing method. Ceramic tile is generally composed of clay, feldspar, and silica, fired at high temperature. Porcelain is a subcategory of ceramic, characterized by a water absorption rate of 0.5% or less according to CSA A363 (Ceramic Tiles). This low porosity makes porcelain denser, more frost-resistant, and suitable for exterior applications in Canadian climates.

Classification According to ANSI A137.1

Although the ANSI standard is American, it is widely referenced in Canada for tile classification. The following table summarizes the main categories:

Exam rule of thumb: the lower the water absorption, the more frost-resistant and stain-resistant the tile. A porous tile (> 7%) must never be installed outdoors or in a wet area.

Classification According to Abrasion Resistance (PEI)

The PEI (Porcelain Enamel Institute) standard classifies the surface glaze into five groups:

Exam trap: a PEI 3 tile is often used in residential kitchens, but a PEI 4 or 5 is required for commercial entrances. Do not confuse glaze hardness with the mechanical strength of the tile body.

Formats and Dimensional Tolerances

Rectified tiles are cut after firing to achieve exact dimensions and perfectly straight edges. Non-rectified tiles have dimensional variations of ± 0.6% to ± 1.0%. For grout joints of 3 mm or less, the use of rectified tiles is mandatory. For joints of 6 mm or more, non-rectified tiles are acceptable.

Tile area calculation: for a rectangular room with length L and width W, the area A = L × W. Add 10% waste for cutting and breakage (15% for diagonal installations). For heated floors, allow 12% waste due to additional cutouts around pipes.

Mortars and Adhesives

Thin-set Mortar

Thin-set mortar is a mixture of Portland cement, fine sand, and polymer additives. It is classified according to ANSI A118.1 (cement-based mortar) and A118.4 (polymer-modified cement mortar). The following designations are essential:

Key rule: for large-format porcelain tiles (≥ 60 cm on one side), use a modified A118.4 mortar with an appropriate trowel. The full coverage rule requires a minimum of 80% coverage for interior floors and 95% for wet or exterior areas.

Medium-bed Mortar

Medium-bed mortar is used for large-format tiles or thick tiles (≥ 1.25 cm). It allows for a thickness of 6 mm to 19 mm under the tile. It is classified according to ANSI A118.4 or A118.15 depending on the polymers added. This mortar must not be used to compensate for an out-of-plane substrate — flatness must be corrected before installation.

Organic Adhesives (Mastic)

Organic adhesives (mastics) are ready-to-use glues based on synthetic resins. They are classified according to ANSI A136.1. Their use is limited to interior walls in dry areas. They are not suitable for floors, wet areas (showers, pools), or low-absorption porcelain tiles. Exam trap: mastic does not cure properly in the presence of moisture — its use is prohibited in showers and saunas.

Grout

Grout is classified according to ANSI A118.6 (cement-based grout) and A118.7 (epoxy grout). The following table compares the two types:

Grout calculation: the amount of grout required depends on the joint width (J), tile thickness (T), and tile dimensions (L × W). The simplified formula is:

Amount (kg/m²) = (J × T × 2) ÷ (L × W) × 1.5 (waste factor)

For a 30 × 30 cm tile, 8 mm thick, 3 mm joint: (0.003 × 0.008 × 2) ÷ (0.30 × 0.30) × 1.5 = 0.0008 kg/m² — this calculation illustrates that the actual quantity is determined by manufacturer tables, but the formula allows you to verify orders.

Substrates and Membranes

Types of Substrates

The substrate is the surface on which the tile is installed. Common substrates include:

Flatness rule: the substrate must be flat to 3 mm over 3 m (3-metre straightedge rule). For large-format tiles, this tolerance is reduced to 1.5 mm over 3 m. An out-of-plane substrate causes cantilevered tiles, cracks, and hollow tiles (hollow sound when tapped).

Waterproofing Membranes

Waterproofing membranes are mandatory in showers, bathtubs, and wet areas. They are classified according to ANSI A118.10 (liquid membranes) and A118.12 (sheet membranes). Liquid membranes are applied by roller or trowel and form a continuous barrier after drying. Sheet membranes (PVC, polyethylene) are bonded with a specific adhesive.

Code requirement: according to the National Building Code of Canada (NBC), shower walls must be waterproofed to a minimum height of 1.8 m above the drain. The shower floor must be waterproofed over its entire surface, with a wall upturn of at least 150 mm.

Uncoupling Membrane

The uncoupling membrane (e.g., uncoupling mat type) absorbs differential movement between the substrate and the tile. It is recommended for heated floors, wood substrates, and large surfaces. It is classified according to ANSI A118.12. This membrane reduces the transmission of substrate cracks to the tile.

Material Selection by Application

Residential Areas

Commercial and Institutional Areas

Commercial areas require PEI 4 or 5 class tiles, with a coefficient of friction (COF) of at least 0.6 for dry floors and 0.8 for wet areas. Commercial kitchens require slip-resistant tiles with epoxy grout to resist grease and acids. Hospitals require tiles with antimicrobial properties and wide joints (≥ 3 mm) for ease of cleaning.

Exterior Areas

For exterior applications in Canada, the tile must have a water absorption of ≤ 0.5% (vitrified porcelain) and frost resistance conforming to CSA A363. The mortar must be polymer-modified (A118.4) and the grout must be epoxy or modified cement-based. A minimum slope of 2% (2 cm per metre) is required for water drainage.

Storage and Handling

Storage Conditions

Tiles must be stored in a dry location, protected from weather and extreme temperature variations. The ideal temperature is between 10 °C and 30 °C. Tiles must be stored flat, on pallets, never on edge (risk of warping). Boxes must be stacked in stable piles, with a maximum height of 1.5 metres to avoid crushing the bottom boxes.

Golden rule: tiles must be acclimatized to the room temperature where they will be installed for at least 48 hours before installation. This acclimatization prevents thermal shock and dimensional variations after installation.

Handling and Safety

Lifting heavy tiles (≥ 25 kg per box) must be done by two people or with lifting equipment. Large-format tiles (≥ 60 × 60 cm) must be transported vertically with rigid support. Sharp edges require protective gloves. Natural stone tiles must be handled with suction cups to avoid fingerprints.

Receiving Inspection

Upon receipt, verify:

Exam trap: tiles of the same shade but from different lots must be mixed during installation to avoid distinct colour zones. Never install all tiles from one lot in a single area.

Applicable Canadian Standards

CSA A363 — Ceramic Tiles

This standard defines manufacturing requirements, test methods, and performance criteria for ceramic tiles in Canada. It covers water absorption, flexural strength, frost resistance, and abrasion resistance.

CSA A82.30 — Cement Boards

This standard specifies requirements for cement boards used as tile substrates in wet areas. It covers composition, thickness, flexural strength, and water permeability.

National Building Code of Canada (NBC)

The NBC, in Section 9.30 (Floor Coverings) and 9.31 (Moisture Protection), requires that ceramic floor coverings be installed on an adequate substrate, with appropriate slope in wet areas, and that showers be waterproofed in accordance with the requirements described above.

Referenced ANSI Standards

Although ANSI standards are American, they are adopted by the Canadian industry for the classification of mortars, grouts, and membranes. The key standards are:

Practical Calculations for the Exam

Area and Waste Calculation

For a room measuring 4.5 m × 3.2 m:

Number of Tiles Calculation

For 30 × 30 cm tiles (0.09 m² per tile):

Thin-set Mortar Quantity Calculation

Thin-set mortar consumption depends on the trowel used:

Golden rule: the trowel must be chosen to achieve full coverage of the tile back. The notch must be at least 1.5 times the tile thickness for large-format tiles.

Pitfalls to Avoid

Summary

Self-Assessment Questions

This chapter prepares you for Red Seal questions on materials. Review the standards, classifications, and calculations — these elements represent approximately 15% of the exam questions.