Tile is one of the most permanent finishes in a home. Unlike paint or flooring that can be swapped out in a weekend, tile installation is a multi-step process involving substrate preparation, mortar, adhesive, grout, and sealer — each of which can fail independently if done incorrectly. A bad tile job doesn’t just look wrong. It can trap moisture behind the tile causing mold and structural damage, fail to drain correctly in a shower causing water infiltration, or crack prematurely because the substrate wasn’t adequately prepared.
It’s also a trade with an enormous skill range. An experienced tile setter brings knowledge of substrate preparation, tile layout geometry, mortar coverage standards, grout joint sizing, and waterproofing integration that a general handyman with a tile saw doesn’t have. The visible surface of a professionally set tile job and an amateur one can look nearly identical on installation day. The difference appears over the next five years.
The questions in this guide apply whether you’re hiring for a shower installation, a kitchen backsplash, a bathroom floor, a mudroom, an exterior tile project, or a large-format porcelain job.
“The two questions that tell me most about whether a homeowner is going to be happy with the outcome are: what substrate is going in, and what’s the layout plan before the first tile is set? Those two things — what’s behind the tile and where the tile pattern starts — determine almost everything about the quality and appearance of the finished job. A tile setter who doesn’t raise both topics before starting is guessing about one of them.”
— Ervis from LevelUp Tiling, tile installation specialist with 10 years of experience in residential and commercial tiling, focused on quality workmanship, clean finishes, and attention to detail
Table of Contents
Before You Call Anyone
What type of tile project do you have?
Tile installation varies significantly in complexity and requirements:
Shower or tub surround: The highest-stakes tile application — requires proper waterproofing behind the tile, correct substrate, appropriate slope to drains, and specific grout and adhesive products rated for wet areas. Failure here causes moisture damage that may not be visible for years.
Bathroom floor: Requires appropriate substrate stiffness (tile cracks if the floor flexes), correct drain integration, and appropriate slip resistance rating on the tile surface.
Kitchen backsplash: Lower-stakes application, but still requires appropriate adhesive, proper layout planning around outlets and obstacles, and correct grout sizing for the tile format.
Large-format tile (24″x24″ and larger): Requires flatter substrate, specific back-butter technique, and larger coverage equipment. More demanding installation than standard tile.
Exterior tile: Requires frost-resistant tile and adhesives, and specific installation techniques for freeze-thaw environments.
Heated floors: Radiant heat systems under tile require specific installation sequence and compatible products.
What tile have you selected, or are you selecting?
If tile isn’t selected yet, a knowledgeable tile setter can advise on appropriate formats, materials, and grout joint sizing for your specific application. If tile is already selected, confirm it’s appropriate for the application — not all tile is suitable for floors, wet areas, or high-traffic applications.
Questions to Ask Before Hiring
Are you a licensed business with insurance and workers’ compensation coverage?
Tile work often involves cutting equipment, kneeling work in confined bathroom spaces, and is typically subcontracted work in renovations. Liability insurance covers damage to your property. Workers’ compensation coverage covers workers if injured.
Ask for a certificate of insurance and workers’ compensation coverage Clearance Certificate.
What credentials or training do you hold?
The tile installation trade has several professional credentials:
TTMAC (Terrazzo, Tile and Marble Association of your country): The primary Canadian trade association for tile setters. Membership indicates professional commitment and access to technical standards.
CTEF (Ceramic Tile Education Foundation) Certified Tile Installer (CTI): An American certification widely held by Canadian installers. Requires passing a hands-on skills assessment.
Red Seal (Terrazzo, Tile and Marble Setter): The inter-regional trade certification for tile setters. The highest formal credential.
Ask what credentials the installer holds and verify them where possible.
How many years have you been setting tile, and do you specialize in this type of work?
Experience with the specific application matters. Ask specifically: how many shower installations have you done? How many large-format tile projects? How many exterior tile installations? A tile setter who does primarily kitchen backsplashes may not have adequate experience for a complex shower with custom niches and heated floors.
Questions About Substrate and Waterproofing
What substrate will be used in the shower or wet area?
This is the most important technical question for any shower or wet-area tile installation. The substrate is what the tile is bonded to — and it must be stable, moisture-resistant, and appropriate for the waterproofing system being used.
Standard drywall: Never appropriate behind tile in a shower or wet area. Absorbs moisture, deteriorates, and is a primary cause of mold behind shower tile.
Moisture-resistant drywall (greenboard): Not appropriate behind shower tile. Moisture-resistant at the paper face, but absorbs water at cut edges and fails in sustained wet environments.
Cement board (HardieBacker, Durock, Wonder Board): Concrete-based backer board. Doesn’t deteriorate with water exposure. A good substrate for tile in most applications, but still requires a waterproofing membrane over top in wet areas.
Glass mat gypsum board (DensShield, DensArmor): Glass mat facing replaces paper. More moisture-resistant than standard gypsum products. Appropriate for tile in many applications.
Foam board systems (Schluter KERDI-BOARD, Wedi): Extruded polystyrene foam panels. Inherently waterproof when properly seamed and detailed. Combined substrate and waterproofing layer.
Ask specifically what substrate is being used and why it’s appropriate for your application.
For more: Questions to Ask a Tile Setter About Waterproofing and Substrate
What waterproofing system is being used in the shower?
Separate from the substrate question, ask specifically what waterproofing membrane or system will be applied. Common systems:
Schluter KERDI: Sheet membrane bonded to the substrate with polymer-modified thinset. Very reliable when installed correctly. Requires specific compatible mortars and accessories.
Liquid-applied membranes (RedGard, Laticrete Hydro Ban, Mapei Mapelastic): Applied by roller in multiple coats. Effective at the correct thickness and coverage.
Sheet membranes (CPE, PVC liner): Used in traditional mortar bed shower installations.
Ask which system is being used, how it will be applied, and how corners and seams will be detailed.
Questions About Layout and Design
What is the layout plan, and will you show it to me before any tile is set?
Tile layout determines where cuts fall, whether the pattern is symmetrical, and how the finished installation looks. Key considerations:
- Where does the layout start? (Typically centered on a focal point — the main wall, the shower niche, the center of the room)
- Where will cuts fall? (Cuts at the edges of a room should be roughly equal and at least half a tile width)
- For large-format tile: how will the pattern align across the room, and how will grout joints align at transitions?
Ask the setter to show you the layout plan on the actual surface (using chalk lines or dry-laid tiles) before any adhesive is applied.
What a good answer looks like: A described layout approach with a specific plan for the focal point and edge cuts, shown to you before setting begins.
What grout joint size will be used?
Grout joint width affects both appearance and function. Smaller joints (1/16″ to 1/8″) create a more seamless look. Larger joints (3/16″ to 1/4″+) accommodate variation in tile size and allow more flexibility in installation.
The correct joint size depends on:
– Tile type (rectified vs. non-rectified — rectified tile has precisely cut edges and can use smaller joints)
– Tile size (larger tiles require larger joints proportionally)
– Application (floor tile joints should be larger than wall tile joints in the same installation to accommodate movement)
Ask what joint size is being specified and why.
For more: Questions to Ask a Tile Setter About Layout and Materials
Questions About Materials
What thinset mortar are you using, and is it appropriate for this tile and application?
Thinset mortar (tile adhesive) varies significantly:
Standard (unmodified) thinset: Basic adhesive. Not appropriate for large-format tile, glass tile, or wet areas.
Polymer-modified thinset: Has polymer additives that improve bond strength, flexibility, and water resistance. Required for most wet-area applications and recommended generally.
Large-format tile requires medium-bed or large-format specific mortars: Standard thinset applied too thickly sags; large-format specific mortars maintain their position and provide adequate coverage.
Epoxy mortar: Two-component adhesive system. Very high bond strength and chemical resistance. Used for some specialty applications.
Ask what thinset is being used and whether it’s rated for the specific tile material and application.
What grout are you specifying?
Grout type significantly affects appearance and maintenance:
Sanded grout: For joints 1/8″ and wider. Contains sand aggregate. More porous than epoxy — benefits from sealing.
Unsanded grout: For joints narrower than 1/8″. Used on polished or delicate tiles where sanded grout would scratch.
Epoxy grout: Two-component system. Stain-resistant, color-stable, and essentially impervious to water. More difficult to install. The best performing grout for shower applications.
Modified grout: Many quality grouts now include polymer additives that improve performance without the full cost of epoxy.
Ask what grout is specified for each area and whether sealing is required.
Red Flags to Watch For
Standard drywall proposed as a substrate in a shower. This is a fundamental installation error. Any proposal to tile directly over standard drywall in a shower is wrong.
No waterproofing system specified for a shower. The substrate alone is not waterproofing. Ask specifically what membrane system is going behind the tile in any wet area.
No layout plan shown before installation begins. Starting tile without establishing the layout wastes material, creates asymmetrical results, and is very difficult to correct after mortar sets.
Mortar coverage not mentioned. Professional tile installation standards (ANSI A108) require minimum 80% mortar coverage behind each tile (95% in wet areas). A setter who doesn’t mention coverage isn’t thinking about it.
Unable to name the products being used. A professional tile setter knows exactly what thinset, grout, and waterproofing product they’re using and why.
For a full guide: Red Flags When Hiring a Tile Setter
Before They Start: A Quick Checklist
- Business registration and insurance verified
- Workers’ compensation coverage clearance verified
- Credentials confirmed (TTMAC, CTI, Red Seal)
- Substrate specified and confirmed appropriate for application
- Waterproofing system specified for all wet areas
- Layout plan shown and approved before any tile is set
- Thinset, grout, and sealer products specified in writing
- Mortar coverage standard confirmed (80% minimum / 95% for wet areas)
- Written quote with all specifications
Related Questions
- Questions to Ask a Tile Setter About Waterproofing and Substrate
- Questions to Ask a Tile Setter About Layout and Materials
- Questions to Ask a Tile Setter During the Job
- How Much Does Tile Installation Cost ?
- Red Flags When Hiring a Tile Setter
- What to Do If a Tile Setter Does Bad Work
- How Do I Choose the Right Tile for My Project?
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