Specifying and Installing Movement Joints
Designed to enhance your space, Atrim combines experience and innovation to only offer the finest quality profiles manufactured from top quality materials. Atrim’s extensive professional portfolio includes a wide range of Movement Joints.
The inclusion of Movement Joints in a floor, and their type and location are critical to ensuring good tiling. To help you determine where to include Movement Joints in your next tiling project, we have put together this guide to Specifying and Installing Movement Joints.
An overview of movement joints
The tiling profile known as a Movement Joint generally takes the form of a bi-material strip designed to be included seamlessly into a tiled surface. It's underside incorporates an anchoring leg or legs and it's upper surface is flush with and closely abutted to the adjacent tile edge(s).
Movement Joints act as a break in a field or bay of tiling and are designed to absorb various forces arising from the movement within the surface and other factors. In essence, Movement Joints divide the surface into distinct ‘bays’, providing protection from multi-directional movement.
Why Movement Joints are required in tiled floors
Including Movement Joints in a tiled floor will enable tiles to be subject to certain inevitable stresses without cracking.
A tiled surface is essentially rigid in nature, and therefore is susceptible to damage caused by movement. Over time, a floor is subject to several different stresses that cause movement. These include mechanical, thermal and moisture-related forces. Mechanical forces include moving loads e.g. personnel foot traffic; static loads e.g. furniture standing on the tiles, and fixtures, or obstacles, around which the tiled floor is laid. Sources of thermal stresses include radiant heating, sunlight and under-tile heating, and floors expand and contract most under changes in temperature. Other stresses, despite being smaller factors, are still relevant, and include changes in ambient moisture, and this can affect rate of expansion and contraction of tiles and most other building materials.
The type of Movement Joint required will depend on the intended use of the floor, the tile size the movement potential. Tiles – whether ceramic, porcelain or natural stone – are a solid material, and every solid material has its own coefficient of expansion, but these vary widely across building products. Any substrate will expand and contract. Factors such as moisture and thermal conditions cause these dimensional changes, in some cases only microscopic, but even these small changes in dimensions can have catastrophic results without mitigating preparation.
Different Movement Joint types and their uses
There are a variety of Movement Joint designs available, with a design suitable for every application.
Movement Joints are designed for different locations within a floor: Intermediate locations and Perimeter locations.
They are available in different base materials: Aluminium, Stainless-Steel and PVC (and other materials to special order). The infills of flexible strips within the base support is also available in a selection of materials: typically, Neoprene and Polyurethane, and others for specific purposes.
The Atrim range also includes Movement Joints with a removable infill so that this visible wearing part can be replaced over time.
Identifying the optimum locations of Movement Joints
The selection of the correct joint profile, and its placement should be planned before tiling installation, to accommodate the predicted movement.
A Movement Joint must be a continuous straight line across the entire floor. There are various locations where Movement Joints must be used:
- If the subfloor already comprises structural expansion joints in its construction, Movement Joints within the tiled surface should be included and aligned with the existing joints.
- At any changes in substrate, where old concrete meets new screed, or where timber floor meets screed, and so on.
- At perimeters of large tiled areas, including abutting any fixtures such as columns, steps, staircases.
- A maximum bay size bounded by movement joints in a typical tiled floor should not exceed 40 sq.m.
- If a floor on a timber sub-structure spans a supporting wall, a joint should be laid parallel to and directly over the supporting wall.
- Movement Joints should be included throughout a tiled floor surface, to create separated tiled sections. In general, include Movement Joints at intervals of between five and eight linear metres, where more frequent joints (c.5m) are for higher risk floors: timber substrates, underfloor heating applications, high thermal gain potential from sunshine.
The placement of joints aside from specific determining factors
Consider aesthetics, as this is important although secondary to proper function. Where possible (i.e. not defined by the above clauses) align Movement Joints with tile edges.
Divide rooms into sections of tiling that as close to square as possible, rather than long and thin. Divide the space equally with the Movement Joints to give pleasing lines and symmetry. Run Movement Joints at door thresholds in such a position that they are hidden once the door is closed.
Choose an infill colour close to the grout colour, or better still, request a bespoke colour to match tiles and grout exactly, or choose a grout colour that exactly matches the infill colour, for truly unobtrusive Movement Joints.
Deciding which Movement Joints to use
When Movement Joints are placed at their maximum spacing, they should be at least 10mm wide (visible width) and should be as deep as the tile thickness and adhesive zone. Narrower joints can be used in floors where joints are more frequent. Perimeter joints should be at least 6mm wide. These can usually be hidden with a skirting tile.
- For mechanical loads, heavy footfall and exposure to chemical aggression, such as car showrooms, factory environments, airports, etc., stainless-steel movement joints should be selected.
- For lighter-duty applications, choose aluminium.
- For residential use, PVC Movement Joints are usually sufficient.
- Further specifications include London Underground-approved infills.
If you are in any doubt, it is advisable to include a movement joint..
The results of well-installed Movement Joints
The result is a tiled surface which will withstand cracking, tenting and de-bonding from the substrate. Movement Joints from Atrim will give years of hard-working service, and help keep the floor crack-free, long-lasting and serviceable.
Special notes on Atrim Movement Joints
The joints should be positioned under-tile heating zone is able to continue to perform, and that any waterproofing is not compromised.
Consider aesthetics; customers and clients will often shy away from the inclusion of Movement Joints in a tiled floor, and solely on aesthetic grounds this is understandable. The factors to bear in mind are, safety and longevity of the tiled surface, and the long-term aesthetic effect of cracks is more unsightly than a well-placed movement joint.
Trimline Group stock a range of Atrim Movement Joints, which have been selected to ensure we have a supply for every project requirement. The range can be specified for any size of project, including new build housing, retail complexes, swimming pools and saunas, hotels, restaurants, leisure centres, vehicle showrooms, and stations.
For the discerning client, Atrim can supply Movement Joints with infill colours to match any RAL, Pantone or BS4800 to special order.
Combining experience and innovation to only offer the finest quality profiles, Atrim has been repeatedly proven to give the expert finish.
To find out more contact our Technical Team for expert advice and information, or visit: https://www.trimlinegroup.com/tiling-profiles-and-movement-joints/movement-joints