Domakihub How to Install Tile Backer Board: A Step-by-Step Guide
Get a waterproof, long-lasting tile base with the right backer board installation technique.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 5 min read
Tile backer board is the unsung hero of any successful tiling job — skip it or cut corners here and you will be dealing with cracked grout, loose tiles, and damp damage within a few years. The video above shows the process clearly; this guide breaks it into numbered steps with the additional detail needed for the wall and floor conditions common in Greek homes, holiday rentals, and hotel bathrooms. Backer board installation is a skilled DIY task for walls and floors in dry or wet zones, though any work touching structural walls, external waterproofing membranes, or load-bearing floors should always be assessed by a licensed builder before you start.
What is tile backer board and why does it matter?
Tile backer board — also called cement board, Hardie board, or fibre-cement board — is a rigid substrate designed to bear the weight and movement of ceramic or porcelain tiles without flexing. Unlike standard plasterboard (drywall), it will not swell, rot, or crumble when it gets wet. In Greece's climate, where coastal humidity and summer heat create constant expansion-contraction cycles, using the correct backer is the single biggest factor in whether a tiled surface lasts five years or thirty.
The most common types are cement-fibre board (e.g. HardieBacker, BAL Board) in 6 mm for walls and 12 mm for floors, and foam-core waterproof boards (e.g. Wedi, Schluter Kerdi-Board) for wet-room and shower applications. For most bathrooms and kitchens in Greek properties, cement-fibre board onto a masonry or concrete substrate is the standard and most affordable choice.
When to call a licensed professional
If the wall you are tiling is an external wall, a party wall, or any surface that forms part of the building's waterproofing envelope, a licensed structural engineer or builder (diplomas under Greek law) must approve the method before work begins — particularly in apartment blocks where interference with the envelope can affect neighbours and insurance. The same applies if you discover damp, mould, or rising moisture behind an existing surface: the source must be professionally diagnosed and treated before any new board goes up.
For straightforward internal bathroom or kitchen walls and floors on solid masonry or concrete — the most common scenario in Greek construction — an experienced tiler or competent DIYer can handle backer board installation safely using the steps below.
How to install tile backer board: 5 steps
- 1
Prepare the substrate and gather materials
Clear the area and check that the existing surface — masonry, concrete slab, or timber stud frame — is structurally sound, clean, and free of dust, grease, and loose plaster. For floors, check the subfloor deflection: press firmly; any flex or bounce means the subfloor needs reinforcing before you lay board. Gather cement-fibre backer board (6 mm for walls, 12 mm for floors), tile adhesive or a dedicated backer board mortar, alkali-resistant fibreglass tape, waterproofing membrane or tanking slurry (for wet zones), appropriate screws (corrosion-resistant, self-drilling), a scoring knife or angle grinder with a diamond blade, and a drill. Calculate board area plus 10 % for cuts and waste.
- 2
Cut the boards to size
Cement-fibre board is best cut using the score-and-snap method for straight cuts: use a straight edge and a sharp carbide-tipped scoring knife, score firmly two or three times along the line, then snap the board over the edge of your work surface. For curves or notches around pipes and outlets, use an angle grinder fitted with a diamond blade and work outdoors or with good ventilation — the dust is fine silica and must not be inhaled. Always wear a P2/FFP2 dust mask, safety glasses, and gloves. Plan your layout so joints in the backer board do not line up with joints in the subfloor or stud frame.
- 3
Apply mortar or adhesive and fix the boards
For floors, spread a layer of tile mortar (thin-set) over the subfloor using a notched trowel, set each board into the mortar, and immediately fix it with corrosion-resistant screws at 200 mm centres across the field and 150 mm around the perimeter — keep screws at least 12 mm from the board edge to avoid crumbling. For walls on masonry, apply backer board adhesive in dabs or continuous ribbons, press the board firmly, and anchor with appropriate masonry screws. On stud frames, screw directly into studs at the same spacing. Leave a 3 mm expansion gap between boards and a 6 mm gap at floor-wall junctions; never butt boards tight together.
- 4
Tape all joints and seal wet zones
Once all boards are fixed, bed alkali-resistant fibreglass tape over every joint and internal corner using tile adhesive or jointing compound, pressing it fully flat with no bubbles. Any area that will have direct and sustained water contact — shower walls, shower floors, around the bath — must then receive a full waterproofing membrane or tanking slurry coat applied over the entire boarded surface, not just the joints. Follow the manufacturer's cure time (usually 24 hours minimum) before proceeding. This step is non-negotiable in Greece where seasonal holiday lets can sit unventilated for weeks at a time.
- 5
Check flatness, allow to cure, then tile
Use a long spirit level or straight edge to check the finished surface for flatness; any high spots can be lightly sanded down, and low spots can be built up with additional adhesive during tiling. Allow the board installation and any waterproofing membrane to cure fully — typically 24–48 hours depending on temperature and humidity. Greece's summer heat speeds drying but can also cause rapid surface drying that leaves the interior under-cured: keep the area shaded and moderately ventilated rather than exposing it to direct midday sun. Once fully cured, the surface is ready for tile adhesive and tiles using standard tiling technique.
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FAQ
- Can I tile directly onto plasterboard instead of backer board?
- Standard plasterboard is not suitable for any tiled area that will get wet — it absorbs moisture, swells, and eventually disintegrates behind the tiles. In dry areas away from splashing (e.g. a feature wall in a living room) moisture-resistant drywall can work, but for kitchens, bathrooms, and anywhere near water, cement-fibre backer board is the correct substrate.
- How thick should the backer board be for a bathroom floor?
- For floors, use 12 mm cement-fibre board as a minimum. This provides enough rigidity to prevent flex under foot traffic and the weight of large-format tiles. Walls take 6 mm board, which is lighter and easier to handle for vertical fixing. Some premium foam-core boards are thinner but achieve equivalent performance through their composite structure — always follow the manufacturer's loading specification.
- Do I need a building permit to tile a bathroom in Greece?
- Replacing like-for-like tiles and backer board on existing internal walls and floors is generally classed as routine maintenance and does not require a permit under Greek building regulations. However, if the work involves altering the bathroom layout, moving drainage, modifying load-bearing elements, or changing the building envelope (e.g. adding a window or enlarging a wet room into an adjacent space), a permit and a licensed engineer are required. When in doubt, consult a local civil engineer (πολιτικός μηχανικός) before starting.