A perfect tiling result doesn't start with the tile, but with the substrate. Wood "works," anhydrite requires sanding and priming, underfloor heating creates extra stresses, and tiling over existing tiles stands or falls with the correct primer and adhesive choice.
In this guide, you will go through each substrate:
- what to pay attention to (moisture, flatness, adhesion, movement),
- the preparation (cleaning, sanding, priming, leveling),
- which tile adhesive is most practical in real-world application.
Tip: Working on a project and want to quickly choose the right adhesive? Check out the Hammerfast Tile Adhesive collection.
Quick checklist before you start
- Firm, flat, and clean: remove dust, cement laitance, grease, loose particles, and paint residues.
- Moisture check: never tile "on a whim" on a still damp screed or anhydrite.
- Absorbent or non-absorbent? That determines your primer choice.
- Movement/stress: always account for expansion/contraction with wood, underfloor heating, and exterior work.
1) Tiling on wood or sheet material
Wood and sheet materials are critical because they can move due to load, expansion, and contraction. This can build up tension in the adhesive/grout and ultimately lead to cracks or delamination.
Approach in brief
- Ensure the construction is rigid and stable (minimize deflection).
- Consider decoupling (e.g., decoupling mat) to prevent movements from the substrate from being transferred 1-to-1.
- Preferably use a flexible tile adhesive on floors and for high-risk substrates.
Product choice (practical): in many situations, a flexible C2TE-S1 adhesive is the safest. For example, consider Hammerfast Seramix Flex (versatile, even for "challenging" substrates).
2) Tiling on concrete (wall/floor)
Concrete can be tiled perfectly, but timing and preparation are crucial. New concrete must be sufficiently cured, and the substrate must be clean and assessed for absorbency.
Approach in brief
- Check if the concrete is old/cured enough.
- Test if the substrate is absorbent (and choose primer/adhesive accordingly).
- Substrate free of dust, cement laitance, curing agents, oil, and loose parts.
Product choice: for standard indoor work, a strong cement-based adhesive is often sufficient. In more demanding conditions or larger temperature differences, a polymer-modified adhesive is more logical, such as Hammerfast RM-900Y.
3) Tiling on cement screed
Cement screeds are common in new builds and commercial projects. The main pitfall: tiling before the floor is truly dry, or tiling on a floor that is not flat enough.
Approach in brief
- Check if the screed is sufficiently dry.
- Is the floor not flat? First level it, then tile.
- Remove dust and prime if necessary (depending on absorbency).
Product choice: for floors (especially with load, larger tiles, or stresses), Hammerfast Seramix Flex is a safe all-round choice.
4) Tiling on plasterboards or plaster render
Plaster can be suitable, but only if the wall is sufficiently rigid and correctly constructed. In the Netherlands, paste adhesive is often used on walls because it is ready to use immediately.
Plasterboards
- Ensure boards are sufficiently and neatly screwed (stable, rigid substrate).
- If in doubt, check suitability with the board supplier (especially in wet areas).
Plaster render
- Work on a sufficiently thick, load-bearing layer (do not apply "too thin").
Product choice (wall/interior): do you want to work quickly and cleanly on interior walls? Then Hammerfast Pasttile is a ready-to-use 1K paste adhesive for interior wall applications (including bathroom/kitchen).
5) Tiling on existing tiles (tiles over tiles)
Tiling over existing tiles is a quick renovation solution: you save demolition work, but your preparation must be top-notch. The biggest mistake is "just gluing" onto a greasy, glossy tile.
Approach in brief
- Thoroughly degrease (kitchens/bathrooms often have soap and grease film).
- Sand or mechanically roughen the tile (more grip).
- Use a primer for non-absorbent/smooth substrates.
Product choice: as an adhesion bridge on smooth, non-absorbent substrates, Hammerfast Astar F is a logical base. Then, depending on the situation, choose a flexible adhesive (e.g., Seramix Flex) or an extra strong polymer adhesive (e.g., RM-900Y).
6) Tiling on a floor with underfloor heating
Underfloor heating causes additional expansion and contraction. This means more stresses in the tile surface and/or grout. Your adhesive system must be able to absorb some movement.
Approach in brief
- Choose a flexible tile adhesive (to absorb movements/stresses).
- Account for expansion joints and perimeter strips (stresses must be able to dissipate).
- Work neatly with adhesive ridges and buttering-floating for large tiles.
Product choice: Hammerfast Seramix Flex is a C2TE-S1 flexible tile adhesive and is also suitable for underfloor heating.
7) Tiling on anhydrite
Anhydrite is a gypsum-bound screed. This type of floor requires strict preparation: the floor must be sufficiently dry, sanded, and completely dust-free before priming and gluing.
Approach in brief
- Check residual moisture (anhydrite requires a strict moisture limit).
- Sand carefully and make 100% dust-free.
- Apply the correct primer and choose a suitable tile adhesive.
Product choice: if your project requires extra security (stresses/temperature fluctuations), work with a high-quality flexible or polymer-modified tile adhesive. View the options in the tile adhesive collection.
8) Tiling on balcony, terrace, or outdoors
Outdoor work is one of the most critical applications: weather influences, frost, water, sun, temperature differences, and often large-format tiles with (too) narrow joints. Here, "just enough" material won't cut it.
Approach in brief
- Choose an adhesive suitable for outdoor and frost/water.
- Ensure good drainage/slope and meticulously finish details.
- Respect expansion joints and joint widths (especially for large tiles).
Product choice (outdoor): Hammerfast Seramix Flex is water and frost-resistant and suitable for outdoor applications. For extremely harsh conditions and larger temperature differences, Hammerfast RM-900Y is a strong option.
Grouting: complete the system
A good adhesive is the foundation, but the grout largely determines the appearance and durability. Working with narrow to wider joints and want a strong, water-resistant joint? Then check out Hammerfast Hammerfuga (2–10 mm).
Frequently Asked Questions
Which tile adhesive should I choose for “challenging” substrates like wood or underfloor heating?
For substrates with movement/stress, preferably choose a flexible tile adhesive. In practice, a C2TE-S1 adhesive is often the safest choice, especially with underfloor heating or renovation.
Can I tile directly on anhydrite?
Only if the anhydrite is sufficiently dry, well-sanded, and completely dust-free. After that, you use the correct primer and a suitable tile adhesive.
How do I tile over existing tiles?
Degrease and roughen the old tiles, use a primer for non-absorbent/smooth substrates, and then choose an appropriate (preferably flexible) tile adhesive.
When can I tile concrete?
Concrete must be sufficiently cured. Also, check if the concrete is absorbent and ensure the substrate is clean and load-bearing.
Paste adhesive or powder adhesive on the wall: which is better?
Both are possible. Paste adhesive works quickly because it's ready-to-use and often popular for interior wall applications. Powder adhesive is versatile and often chosen when extra strength/flexibility is needed.
Which primer should I use on non-absorbent substrates like old tiles?
Use a primer intended for non-absorbent and smooth substrates to create a reliable bond bridge before you start gluing.
Want to choose the right products directly? View all Hammerfast tile adhesives or contact us for project advice.
