Adhesives, Mortars, and Setting Systems

Adhesives, Mortars, and Installation Systems

Introduction

This chapter covers all the knowledge required for the Red Seal exam concerning adhesives, mortars, and installation systems used in the tile-setting trade. Selecting the right installation system is a critical decision that determines the durability, performance, and compliance of the installation. You must master material properties, application methods, consumption calculations, and Canadian standards requirements.

Classification of Adhesives and Mortars

Cement-Based Mortars

Cement-based mortars are classified according to ANSI A118.1 (an American standard adopted by the Canadian industry) and the National Building Code of Canada (NBC) . Four main types are distinguished:

Type	Designation	Compressive Strength (28 days)	Typical Use
M	Portland cement mortar	≥ 17.2 MPa	Floors, exterior walls
S	Portland cement mortar	≥ 12.4 MPa	Interior walls, floors
N	Portland cement mortar	≥ 5.2 MPa	Light-duty applications
O	Lime mortar	≥ 2.4 MPa	Repairs, non-structural

Traditional setting mortar (mud bed) consists of Portland cement, sand, and water. The typical ratio is 1:4 (cement:sand) for setting beds, with a thickness of 19 mm to 38 mm. The leveling mortar (mud bed) must have a consistency that allows smoothing while maintaining its shape.

Thin-Set Adhesives

Thin-set adhesives are classified according to ANSI A118.1, A118.4, and A118.11. They are applied in layers 3 mm to 6 mm thick. The main categories:

Cementitious adhesive (thin-set mortar) : A mixture of Portland cement, fine sand, and polymer additives. Available in:

Type 1: Interior use only

Type 2: Interior and exterior use, moisture resistant

Epoxy adhesive: A two- or three-component system (resin, hardener, filler). Superior chemical resistance, used for countertops, pools, and high-performance areas.

Organic adhesive (mastic) : Solvent-based or water-based, used only for interior walls in dry areas. Not suitable for floors or wet areas.

Grouting Mortars

Grouting mortars are classified according to ANSI A118.6 and A118.7:

Type	Joint Width	Use
Sanded cement grout	≥ 3 mm	Floors, wide joints
Unsanded cement grout	≤ 3 mm	Walls, narrow joints
Epoxy grout	Variable	Chemical, food-processing areas
Polymer grout	Variable	High-traffic areas

Cement grout is a mixture of Portland cement, pigments, and additives. Epoxy grout consists of epoxy resin and hardener, offering superior resistance to stains and chemicals.

Installation Systems

Traditional Installation (Mortar Bed)

Traditional installation involves applying a cement mortar bed 19 mm to 38 mm thick over a prepared surface. This system is used for:

Floors with significant level discrepancies

Exterior surfaces

Heavy-traffic areas

Large-format tiles

Procedure:

28.Prepare the surface (cleanliness, moisture, flatness)

29.Apply a bonding coat (slurry) to the substrate

30.Spread the mortar with a trowel, leveling it with a straightedge

31.Set the tiles, pressing them into the mortar

32.Adjust alignment with spacers

33.Allow 24 to 48 hours of curing before grouting

Thin-Set Installation

Thin-set installation is the most common method for residential and light commercial applications. The adhesive thickness is 3 mm to 6 mm.

Surface requirements:

Flatness: ≤ 3 mm over 3 m (1/8" over 10' tolerance)

Cleanliness: free of dust, grease, oil

Moisture: ≤ 4% for concrete substrates (moisture meter test)

Temperature: 10°C to 32°C (50°F to 90°F)

Procedure:

42.Mix the adhesive according to manufacturer specifications

43.Apply the adhesive with a notched trowel (choose notch size based on tile format)

44.Create uniform ridges in a single direction

45.Set tiles with a twisting motion

46.Check adhesive transfer (≥ 80% for dry areas, ≥ 95% for wet areas)

47.Adjust with spacers

48.Allow 24 hours of drying before grouting

Installation over Waterproofing Membranes

Waterproofing membranes are mandatory in showers, baths, and wet areas according to the National Building Code of Canada (NBC) , Section 9.29. Membrane types:

Polyethylene membrane: Sheet of 6 mil (0.15 mm) minimum, installed beneath the mortar

Liquid membrane: Applied by roller or brush, forming a continuous barrier

Self-adhesive membrane: Sheet with pre-applied adhesive

Cement-based membrane: Two-component system applied in a thin layer

Installation requirements:

Joint overlap: ≥ 50 mm (2")

Sealing at penetrations (pipes, drains)

Watertightness test: 24 hours before tile installation

Protection against mechanical damage

Installation over Special Substrates

Cement backer boards (Durock, Hardibacker) :

Thickness: 6 mm to 15 mm

Fastening: corrosion-resistant screws or nails

Joints: mesh tape and thin-set mortar

Fastener spacing: 200 mm on center

Water-resistant gypsum board (type X) :

Use: dry areas only

Joint treatment: tape and joint compound

Priming: required before installation

Wood floors:

Requirement: double floor with joist spacing ≤ 300 mm

Uncoupling membrane: mandatory to prevent cracking

Adhesive: must be flexible (deformable)

Calculations and Quantities

Calculating Adhesive Consumption

Adhesive consumption depends on:

The size of the notched trowel

The tile format

The regularity of the surface

Basic formula:

Consumption (kg/m²) = Area covered by trowel (m²/kg) × Correction factor

Trowel Notch	Tile Format	Consumption (kg/m²)
6 mm × 6 mm	≤ 200 mm	2.5 – 3.5
10 mm × 10 mm	200 – 400 mm	3.5 – 5.0
12 mm × 12 mm	400 – 600 mm	5.0 – 7.0
20 mm × 20 mm	≥ 600 mm	7.0 – 10.0

Calculating the number of bags:

Number of bags = (Total area × Consumption) ÷ Bag weight

Example: Area of 45 m², consumption of 4 kg/m², 20 kg bags

Number of bags = (45 × 4) ÷ 20 = 9 bags

Calculating Grout Quantity

Formula:

Quantity (kg) = (Length of joints × Width × Depth) × Density of grout

Typical density: 1.5 – 1.8 kg/L for cement grout

Simplified method:

Quantity (kg/m²) = (Joint width + Tile thickness) × Joint width × Factor

Tile Format	Joint Width	Consumption (kg/m²)
100 × 100 mm	3 mm	0.3 – 0.5
200 × 200 mm	5 mm	0.5 – 0.8
300 × 300 mm	8 mm	0.8 – 1.2
600 × 600 mm	10 mm	1.0 – 1.5

Calculating Drain Slopes

The minimum slope for shower floors is 1:50 (2%) according to the NBC, Article 9.31.4.1. This means a drop of 20 mm per meter.

Formula:

Drop (mm) = Distance from drain (m) × 20 mm/m

Example: Distance of 1.5 m from the drain

Drop = 1.5 × 20 = 30 mm

Applicable Standards and Codes

National Building Code of Canada (NBC)

The NBC is the primary reference for tile installations in Canada. Relevant articles:

Article 9.29.1.1: General requirements for floor coverings

Article 9.29.5.1: Installation of ceramic tiles

Article 9.31.4.1: Shower floor slopes

Article 9.31.5.1: Shower waterproofing

Key NBC requirements:

Tiles must be installed over a stable and continuous substrate

Surfaces must be prepared to ensure adhesion

Wet areas must have a waterproofing membrane

The minimum slope for shower floors is 1:50

CSA Standards

Relevant CSA (Canadian Standards Association) standards:

CSA A23.1: Concrete and related materials (preparation of concrete substrates)

CSA A82: Ceramic tiles (classification and requirements)

CSA A82.1: Test methods for ceramic tiles

ANSI Standards

ANSI (American National Standards Institute) standards are widely used in the Canadian industry:

ANSI A108: Installation of ceramic tiles

ANSI A118.1: Dry-set mortars

ANSI A118.4: Polymer-modified adhesives

ANSI A118.6: Grouting mortars

ANSI A118.7: Polymer-modified grouting mortars

ANSI A118.10: Waterproofing membranes

ANSI A118.11: Epoxy adhesives

Surface Preparation

General Requirements

Surface preparation is responsible for 80% of installation failures. The fundamental requirements:

129.Flatness: ≤ 3 mm over 3 m for thin-set installation

130.Cleanliness: Free of dust, oil, grease, paint

131.Dryness: Moisture ≤ 4% for concrete (moisture meter test)

132.Soundness: Surface capable of supporting the weight of the installation

133.Temperature: 10°C to 32°C during installation and curing

Concrete Substrates

Specific requirements:

Minimum age: 28 days before installation

Compressive strength: ≥ 25 MPa

Relative humidity: ≤ 75% (probe test)

No laitance: must be removed by shot blasting or acid etching

Moisture testing:

Plastic sheet test: Place a 500 mm × 500 mm sheet, seal the edges, check after 24 hours

Moisture meter test: Measure the relative humidity of the concrete

Calcium chloride test: Measure the moisture vapor emission rate (≤ 3 kg/100 m²/24h for sensitive adhesives)

Gypsum Substrates

Specific requirements:

Type X panels for wet areas

Joints treated with tape and compound

Primer: mandatory before installation

Cleanliness: free of excess joint compound

Wood Substrates

Specific requirements:

Double floor: subfloor + underlayment

Joist spacing: ≤ 400 mm

Uncoupling membrane: mandatory

Adhesive: must be flexible (deformable class)

Choosing the Installation System

Selection Factors

The choice of installation system depends on:

Factor	Considerations
Substrate type	Concrete, gypsum, wood, cement backer board
Location	Interior, exterior, wet area
Tile format	Small, medium, large format
Traffic	Residential, commercial, industrial
Exposure	Water, chemicals, freeze-thaw
Timeline	Material availability, curing time

Selection Matrix

Application	Recommended System	Adhesive	Grout
Residential floor	Thin-set	Modified thin-set mortar	Polymer-modified cement grout
Commercial floor	Mortar bed or thin-set	Modified thin-set or epoxy	Epoxy or polymer grout
Shower	Membrane + thin-set	Modified thin-set mortar	Polymer-modified cement grout
Exterior	Mortar bed	Modified thin-set mortar (Type 2)	Polymer-modified cement grout
Pool	Thin-set	Epoxy	Epoxy
Countertop	Thin-set	Epoxy	Epoxy

Considerations for Large Formats

Large-format tiles (≥ 600 mm) require special considerations:

Notched trowel: ≥ 12 mm × 12 mm

Adhesive transfer: ≥ 95%

Setting technique: back-buttering method

Substrate flatness: ≤ 2 mm over 3 m

Use of leveling systems (clips and wedges)

Installation Procedures

Mixing Adhesives

Mixing rules:

172.Use a low-speed mixer (300-400 RPM)

173.Add the adhesive to the water (never the reverse)

174.Mix until a homogeneous consistency is achieved

175.Allow to slake for 5-10 minutes

176.Remix briefly before use

177.Respect the pot life

Common errors:

Adding water to extend working time

Mixing large quantities that exceed the pot life

Using a high-speed mixer (introduces air)

Adhesive Application

Trowel technique:

184.Apply the adhesive with the flat side of the trowel

185.Comb the adhesive with the notched side at a 45° angle

186.Maintain constant pressure

187.Create uniform ridges in a single direction

188.Do not spread more than can be covered in 15-20 minutes

Open time: The period during which the adhesive remains tacky. Check by touching the surface with your finger. If the adhesive no longer feels sticky, remove it and reapply.

Tile Installation

Setting technique:

192.Set the tile with a slight twisting motion

193.Press the tile into the adhesive

194.Check level with a spirit level

195.Insert spacers (2-3 mm for walls, 3-5 mm for floors)

196.Check alignment with a straightedge or laser

Transfer check: Randomly lift a tile to verify that the adhesive covers ≥ 80% of the surface (≥ 95% for wet areas and large formats).

Grouting

Prerequisites:

Adhesive fully cured (24-48 hours)

Spacers removed

Joints cleaned and free of debris

Procedure:

204.Mix the grout according to specifications

205.Apply with a rubber float at a 45° angle

206.Completely fill the joints

207.Remove excess with the float

208.Allow to set (10-30 minutes depending on type)

209.Clean the surface with a damp sponge

210.Allow 24-72 hours of curing before foot traffic

Final cleaning: Use a specific cleaner to remove cement haze.

Pitfalls to Avoid

213.Not respecting the open time: Adhesive that has skinned over will no longer bond. Always check with your finger.

214.Adding water to the adhesive: This reduces final strength. Never add water after the initial mixing.

215.Ignoring substrate flatness: An uneven surface causes cracked tiles and uneven joints.

216.Using the wrong type of adhesive: Organic mastic is not suitable for floors or wet areas.

217.Neglecting the waterproofing membrane: Mandatory in showers according to the NBC, Article 9.31.5.1.

218.Installing over a damp substrate: Moisture prevents adhesion and causes efflorescence.

219.Not checking adhesive transfer: Insufficient transfer causes hollow tiles and cracking.

220.Grouting too early: The adhesive must be fully cured before grouting.

221.Using an inappropriate trowel: The notch size must match the tile format.

222.Ignoring temperature conditions: Installing below 10°C or above 32°C affects curing.

Exam Tips

Memorize the ratios: 1:4 for setting mortar, 1:50 for shower slopes.

Know the standards: NBC Articles 9.29, 9.31; ANSI A118.1, A118.4, A118.6.

Calculate quantities: Practice adhesive and grout consumption calculations.

Identify applications: Know which system to use for each situation.

Understand the principles: Why the membrane is mandatory, why transfer must be ≥ 80%.

Summary

Cement-based mortars are classified into types M, S, N, O according to their strength.

Thin-set adhesives are applied at 3-6 mm and classified according to ANSI A118.

Traditional installation (mortar bed) is used for uneven surfaces and heavy-traffic areas.

Thin-set installation is the most common method, with strict flatness and cleanliness requirements.

Waterproofing membranes are mandatory in showers according to the NBC.

Adhesive transfer must be ≥ 80% (≥ 95% for wet areas).

The minimum slope for shower floors is 1:50 (20 mm/m).

Quantity calculations depend on the trowel, tile format, and surface area.

The NBC and ANSI standards are the primary references for installations in Canada.

Surface preparation is responsible for 80% of failures.

Pitfalls to Avoid (Summary Table)

Pitfall	Consequence	Prevention
Exceeded open time	Loss of adhesion	Check with finger
Adding water	Reduced strength	Respect the mix
Uneven substrate	Cracked tiles	Level before installation
Wrong adhesive	System failure	Choose according to application
No membrane	Water infiltration	Install per NBC
Damp substrate	Efflorescence	Test moisture
Insufficient transfer	Hollow tiles	Check randomly
Premature grouting	Weak joints	Wait 24-48 hours
Inappropriate trowel	Inadequate coverage	Choose based on tile format
Inadequate temperature	Abnormal curing	Control the environment

This chapter prepares you to master the technical aspects of adhesives, mortars, and installation systems for the Red Seal exam. Understanding the fundamental principles, applicable standards, and installation procedures is essential for passing the exam and practicing the trade competently.

Adhesives, Mortars, and Installation Systems

Introduction

Classification of Adhesives and Mortars

Cement-Based Mortars

Thin-Set Adhesives

Grouting Mortars

Installation Systems

Traditional Installation (Mortar Bed)

Thin-Set Installation

Installation over Waterproofing Membranes

Installation over Special Substrates

Calculations and Quantities

Calculating Adhesive Consumption

Calculating Grout Quantity

Calculating Drain Slopes

Applicable Standards and Codes

National Building Code of Canada (NBC)

CSA Standards

ANSI Standards

Surface Preparation

General Requirements

Concrete Substrates

Gypsum Substrates

Wood Substrates

Choosing the Installation System

Selection Factors

Selection Matrix

Considerations for Large Formats

Installation Procedures

Mixing Adhesives

Adhesive Application

Tile Installation

Grouting

Pitfalls to Avoid

Exam Tips

Summary

Pitfalls to Avoid (Summary Table)

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