Expansion joints or movement joints are an essential part of any floor tiling installation and must be installed to prevent system failure such as tiles delaminating or grout from cracking.
A ceramic or stone floor is by its nature a rigid surface. All materials, when subjected to temperature fluctuations and humidity will expand and contract at different amounts.
In the case of heated floors, the coefficient of thermal expansion of the background substrate and the type of tile chosen, should not be too dissimilar. If this is not the case, then excessive stresses may be generated within the tiling installation sufficient to result in either debonding or cracking of tiles and grout.
To counteract any potential for trouble within a tiling installation, adequate planning and preparation is crucial, as is the correct selection of materials and placement of movement joints.
Current British Standards state that interior floor tiling (non-heated) should be divided into maximum fields of 10 metres in each direction, whilst externally three metre intervals are required. Movement joints should always be incorporated over existing structural movement joints and perimeters, door openings, columns, kerbs, steps, and at the junctions of different base materials.
Where the floor is subjected to fluctuations in temperature, it is recommended that joints are placed more frequently i.e. the maximum area bounded by intermediate joints within the heated screed should not exceed panels of 40sqm for ceramic and natural stone.
The panels formed should be square to rectangular with a length to width ratio of no more than 8x5m. The width and spacing of intermediate movement joints should be sufficient to accommodate anticipated movement within the floor assembly so that the stresses between the flooring and heated screed remain within acceptable limits.
Stresses from thermal and moisture changes, drying shrinkage, deflection and movement in the substrate affecting the flooring, can cause loss of adhesion resulting in bulging (“tenting/heaving”) or cracking of the tile – even with deformable or highly deformable tile adhesives, normally recommended for tiling onto substrates susceptible to limited movement or thermal changes.
Expansion joints can either be pre-fabricated profiles made of brass, aluminium, stainless steel or PVC or, where applicable a field applied material such as silicone-type sealant.
When sealing movement or expansion joints in floor or wall tiling installations then choosing the right sealant is absolutely essential.
BAL has a number of silicone sealants that are suitable for perimeter sealant movement joints, including BAL Micromax Grout-Effect Sealant with built-in Microban antimicrobial protection for walls and floors.
The product is described as a “unique high-performance sealant that has a matt finish which is colour-matched to BAL Micromax3 ECO high-performance grout”.
Crucially, this means that your soft movement joints are matched in colour and texture to your grout joints.
Curing in 24 hours, the sealant can reportedly be used on most surfaces including porcelain, ceramic, fibreglass, glass, glazed and painted, in dry or wet conditions, internally or externally – including against drain grates.
It is not suitable for swimming pools, aquariums or natural stone, however. If sealing natural stone, BAL recommends the use of ARDEX ST – a neutral cure silicone sealant.
The product is available in 10 colours and complements BAL Micromax3 ECO Grout – the company’s rapid-setting and flexible tile grout for joints from 1-30mm. For larger commercial projects, additional colours can be requested.
Also available from BAL is Micromax Sealant, the company’s original standard silicone sealant. This product provides a gloss finish and is also available in 10 colours, colour-matched with Micromax3 ECO Grout. BAL Micromax Sealant also has in-built Microban anti-mould technology.
www.bal-adhesives.com
