Expansion joint profiles

The profile should be 1 – 2 mm taller than the floor covering, exactly like with tile edging profiles. For a 10 mm tile, choose an 11 – 12 mm profile; for 12 mm porcelain stoneware, a 12.5 – 14 mm profile.
The tile adhesive adds about 1 mm in the thin-bed method, hence this buffer. A profile that's too low will be covered by the tile and lose its protective function; a profile that's too high will protrude and become a trip hazard. At tirocco, aluminium and stainless steel expansion joint profiles for tile coverings are available in heights of 3 – 30 mm, the PVC thick-bed profiles in 30, 40 and 50 mm.
For thick-bed installation, the profile height corresponds to the total build-up height of screed/concrete plus covering. Always measure the build-up height with calipers on the cross section before buying, not based on the tile packaging — the adhesive application varies.

The most professional solution is a cover profile made of aluminium or stainless steel, which is retrofitted onto the joint by gluing or screwing it down without intervention in the flooring. The joint underneath remains fully functional and can continue to move — the profile itself is not anchored in the adhesive bed.
At tirocco there are three variants: the aluminium cover profile (W 60 – 120 mm) for indoor use with an elegant look, the stainless steel expansion joint cover profile with a black rubber casing (W 200 – 250 mm) for industrial and warehouse surfaces also driven on by forklifts, and the T-shaped brass divider profile as a design solution for terrazzo floors.
An expansion joint must never be filled in with grout or concreted over — the movement must be able to be absorbed, otherwise the covering next to it will crack. Silicone alone is only sufficient for narrow structural joints up to about 10 mm wide.

Expansion joints compensate for movements caused by temperature changes, moisture, or mechanical loads in the floor. Without these joints, material tension builds up and causes the tile covering or the screed beneath it to crack.
An expansion joint is mandatory for surfaces larger than 40 m² (according to DIN 18560), for underfloor heating, at transitions to other building components, in door openings, and at room boundaries. On terraces and balconies, a joint must be planned more frequently due to the large temperature fluctuations; indoors, a perimeter joint at the walls is often sufficient for small rooms.
Rules of thumb from practice: every 6 – 8 m one expansion joint in the screed, every 25 – 40 m² one field boundary in the tile covering, and one in every door or at every room boundary. If the joint is ignored when tiling, the covering will crack after a few months or years.

In new installations, the profile is laid directly with the tiles in the thin-bed method. For retrofitting a cover over an existing joint, a surface-mounted cover profile is used instead. The two methods differ fundamentally.
New installation in six steps: First, plan the joint position (field sizes, room boundaries, door openings). Second, cut the profile to height of flooring + 1 – 2 mm. Third, apply the adhesive bed on both sides of the joint. Fourth, press the profile with the perforated legs into the adhesive. Fifth, lay tiles on both sides with a 2 – 3 mm gap. Sixth, close the profile joint with flexible silicone or flex grout.
Retrofit cover: Clean the old joint, place the cover profile on both sides of the joint with MS polymer adhesive or assembly adhesive, fix for 24 hours. The profile is not rigidly fastened across the joint, so that the movement is preserved.

The choice depends on the laying system: thin-bed, thick-bed, or floating floor covering. Each variant needs a different profile type.
For tiles in the thin-bed method (3 – 12 mm build-up), aluminium or stainless steel expansion joint profiles with perforated legs and EPDM insert are the right choice. The EPDM insert absorbs the actual movement, the metal legs secure the tile edge. For thick-bed installation directly in screed or concrete (30 – 50 mm build-up), there are PVC expansion joint profiles for thick-bed, which are inserted wedge-shaped into the fresh screed. For floating floors like laminate or vinyl, no profiles with adhesive leg are suitable — here surface-mounted transition profiles or cover profiles are correct, which are screwed or glued onto the perimeter joint.
Never fill laminate with grout: moisture expansion will blow out the filler immediately. Laminate needs about 10 mm expansion distance all around to the wall.

Silicone alone does not replace an expansion joint profile. It is only suitable for narrow movement joints between two tiles or as an elastic perimeter joint at the wall — and even there only as supplementary sealing.
For wide structural joints from about 10 mm, an expansion joint profile with EPDM or rubber insert is the only durable solution. The insert cushions mechanical movement, while pure silicone is torn out of the joint at the third or fourth movement. In addition, silicone ages due to UV radiation, cleaning agents, and water; it must be renewed every 2 – 5 years.
The best solution combines both approaches: an expansion joint profile absorbs the mechanical movement, a silicone perimeter joint on both sides provides watertight sealing. This is the standard procedure in wet areas and on balconies.

An expansion joint (also called a movement joint) absorbs movements from temperature, moisture, or load and separates building components so they can move independently of one another. A construction joint (also called a working joint) arises when two sections of concrete meet with a time delay during pouring — for example on day 1 and day 2 of a base slab.
The functional difference: The expansion joint is active, it moves. The construction joint is passive, it only marks a separation without a movement function. What both have in common is that they must be transferred 1:1 into the tile covering — never tile over them, otherwise the covering will crack.
The sealing differs accordingly: Expansion joints need a profile with elastic insert plus elastic grouting; construction joints are sealed with a joint tape or injection hose in the concrete and can be laid over with a simple divider profile.

Aluminium is the cost-effective standard solution for indoor areas with normal load. Stainless steel V2A is more robust, corrosion-free, and the right choice for wet areas, outdoor areas, or heavily loaded industrial surfaces (forklifts). PVC is only intended for thick-bed installation directly in screed or concrete.
An important note on tile-joint profiles: The EPDM or rubber insert absorbs the actual movement, not the metal itself. Aluminium and stainless steel profiles therefore differ primarily in corrosion resistance and stability of the visible edge, not in expansion performance.
Brass profiles in T-shape, like the divider profile for terrazzo, are a special case — they are primarily intended as a design and dividing line, not as a classic expansion joint. For industrial and forklift-driven surfaces, tirocco offers the stainless steel cover profile with 200 – 250 mm width and rubber casing.

For expansion joints in tile and screed construction, several DIN standards apply in Germany, as well as the ZDB information sheet of the Central Association of German Building Trades, which is considered recognised state-of-the-art.
The most important references: DIN 18560 (Screeds in building construction) regulates movement and perimeter joints in the screed and sets the field size limit at 40 m² or an aspect ratio of 2:1. DIN 18157 (Execution of ceramic coverings in thin-bed) requires that movement joints of the substrate be transferred 1:1 into the covering. DIN 18540 regulates exterior wall joints, DIN 18202 defines permissible movements and dimensional tolerances in building construction.
The practical regulation is the ZDB information sheet "Movement joints in coverings and coatings made of tiles and slabs" — it is considered a binding reference in disputes, even though it is formally not a standard. Rules of thumb from it: every 6 – 8 m an expansion joint, every 25 – 40 m² a field boundary, at all room boundaries and door openings.