8 of 24 Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements Section 09: Building Works  The mixer, bunker, gauge boxes and all tools shall be kept clean, and care shall be taken to ensure that  fresh plaster is not contaminated with set plaster.  Waterproof plaster shall consist of waterproofing compound, cement and sand mixed in strict accord- ance with the manufacturer’s specification. The water proofing compound shall be a mass product of a  repudiated manufacturer and shall be approved by the Engineer.  Plaster shall be of 2 or 3 coats. If plaster is to be applied to smooth surfaces, a dash coat shall be ap- plied as a bonding surface. The dash coat shall be of mush consistency, composed of 1 part Portland  cement and 1.5 parts of sand.  The plaster coats shall be applied according to the thicknesses given below, whereby additional thick- ness, which will be required due to unevenness in the masonry surface, is not included:  All surfaces shall be true to line, level, plumb and all junctions, angles and arises truly scare. On two  or three coat work, the plaster surface shall not show any deviation greater than -+5mm.  Plain finished rendering shall be carried out with 1:5 cement-sand in two or three coats. Three coat  work shall be carried out on metal latching and on other backgrounds which the Engineer determines  by inspection to be too uneven to permit two coat work.  Rendering applied to external walls shall contain a waterproofing agent to the approval of the Engi- neer. Undercoats shall not exceed an average thickness of 10 mm and finishing coats shall have a  thickness of 8 mm to 10 mm. Three coat rendering shall have a total thickness of 35 mm.  Where rendering is to be applied to surface of concrete or block work, such surfaces shall be treated  by a means approved by the Engineer to provide a mechanical key for the rendering.  Where dissimilar wall backgrounds meet to form a continuous surface, a 150 mm wide strip of ex- panded metal shall be fixed over the joint between the dissimilar surfaces before the first undercoat is  applied.  Surfaces shall be cleaned of all residual mould, oil, dust, loose particles and other deleterious material  before rendering work begins.  Each undercoat shall be combed or scratched to provide a key for subsequent coats as soon as under- coat has set firm.  9_Vol3_d4.3_Section 9 building works_en_GIR_rev6.docx  9.1.14.1 Rendering with plain finish  9.1.14 Rendering  9.1.13.7 Tolerances  9.1.13.6 Workmanship  9.1.13.5 Waterproof plaster  Location:  Ceiling  Interior wall  Finish  Thickness of first coat:  15mm  10 mm  10 mm  Thickness of intermediate coat:  --  6 mm  9 mm  Thickness of finish coat:  10 mm 4 mm  6 mm  Total thickness:  25 mm  20 mm  25 mm 