BS 5385-1:2009 pdf free download – Wall and floor tiling一 Part 1: Design and installation of ceramic, natural stone and mosaic wall tiling in normal internal conditions – Code of practice.
5.9 Sealants and back-up materials for movement joints
5.9.1 General
Materials for movement joints should be non-rigid. They should combine the properties of resilience and/or plasticity within the maximum temperature ranges likely to be encountered and should be resistant to mould growth.
5.9.2 Sealants
Joint sealants should be selected and applied in accordance with the guidance given in BS 6213.
Sealant manufacturers’ advice should be taken into account as the properties of individual sealants can vary. A sealant should be capable of accommodating the anticipated amount of movement without loss of adhesion to the sides of the joints and be able to withstand the normal service conditions affecting the installation, e.g. resistant to water, ultraviolet light etc.
Where movement joints are intended to cover structural joints, and frequent movement is possible, class 25 sealants should be used. For joints undergoing smaller and less frequent movement, classes 20 or 12.5 should be considered.
NOTE 1 A given extent of movement can be accommodated either by a wider joint or by the use of a more flexible sealant, or a combination of the two; however, where the class number is less than 20, the sealant might not be suitable over structural movement joints. For a given extent of movement the narrower the joint, the higher the sealant class needed to accommodate the movement.
NOTE 2 Information on sealant installation is given in 6.5.4.
5.9.3 Back-up materials
The compressible back-up material should be a material to which the sealant can not adhere, or one which can be covered with a bond breaker tape to prevent adhesion.
The back-up material in the lower part of the joint should be compatible with the sealant used, should recover after compression and should support the sealant. It should not exude bituminous or oily products and should not absorb excessive amounts of moisture. In particular, its compressibility should be such that when the joint closes, the sealant is not forced out. Typical materials that should be used include closed cell cellular rubber and plastics, such as cellular polyethylene, some fibre building boards, cork boards and mineral or synthetic ceramic cords or blankets
NOTE 1 Back-up materials are available in sheet, strip and cord form in a range of sizes.
NOTE 2 For further information on installing back-up materials see 6.5.3.
5.10 Grouts
5.10.1 General
Grouts should have good working characteristics (e.g. ease of cleaning off the face of the tiles) as well as low shrinkage characteristics and good adhesion to the sides of the tiles. The class stated for a grout should not be taken as any indication of deformability; BS EN 12002 describes test methods for determining the deformability of adhesives and grouts and so on.
5.10.2 Types of grout
5.10.2.1 Proprietary grouts
Proprietary grouts should conform to BS EN 13888:2002, type CG or RG and should be one of the following types.
a) Mixes based on cement and mineral fillers but modified by the inclusion of various additives, including pigments and organic additives, that only require to be mixed with clean water to the recommended consistency (CG).
b) Mixes based on cement and mineral fillers and additives to be mixed with aqueous synthetic polymer dispersions to the recommended consistency (CG).
c) Mixes based on epoxide resin consisting of separate pre-gauged components to be mixed together immediately before use (RG).