## 9.1.12 Tiling 

Tiling shall comprise all required labour, equipment and the supply of the appurtenant materials and structural components including off-loading and storage at the site. 

All tiles and flags for which there are several grades available shall be of the best standard commercial grade, unless grade is stipulated anywhere in the Employer’s Requirements. 

Before starting the work, the Contractor shall ascertain the Employer’s selection of patterns and col- ours and the Contractor shall furnish the Engineer with duplicate samples of the patterns and colours of the materials selected by the Employer. 

Tiling shall be free of any defects and any work that shows signs of bond failures, hollow patches, misalignment, cracking or any other defect. Defective work will not be accepted and shall be removed and replaced by acceptable work. 

In general, tiles shall meet the quality requirements of TS EN ISO 10545. Where tiles and flags are not standardised, the quality features shall satisfy the standard commercial requirements (top surface, par- allelism of edges, colour, and water absorption). All floor and wall tiles shall be from the same batch. 

Glazed ceramic tiles for walls shall be in the colour selected by the Employer, true to shape, flat, free from flaws, cracks and crazing, uniform in colour, keyed on the back. The tiles shall be of a suitable type, size, colour and acid resistance. 

Ceramic tiles at laboratories and chemical storage rooms shall be oil and acid resistant, true to shape, flat, free from flaws, cracks and crazing, uniform in colour and of an approved type, make and colour. 

## 9.1.13 Plastering 

## 9.1.13.1 Sand 

Sand shall be clean and sharp course grit, fresh water river or pit sand and shall be re-washed on site if the silt, loam or clay content exceeds the limits prescribed in TS 3821. The sand shall be obtained from a source approved by the Engineer. 

## 9.1.13.2 Cement 

Cement shall be Portland cement as specified in TS EN 197. The source of cement is subject to the approval of the Engineer and shall not be changed without his prior approval. 

## 9.1.13.3 Water 

For the mixing of mortar and plaster the Contractor shall provide tap water, if not otherwise directed or approved by the Engineer. 

## 9.1.13.4 Mixing of plaster 

Plaster shall be mixed with proportions according to TS EN 998-1. The constituents shall be measured by volume and water added in an amount compatible with workability. 

Plaster shall be mixed in a mechanically operated plaster mixer for at least long enough to make a thorough, complete intimate mix of the materials. The mixing of plaster by hand shall not be permit- ted, unless otherwise directed. 

