Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements Section 09: Building Works  14 of 24 9.1.19 Roofing  9.1.19.1 General  9.1.19.2 Waterproofing and Insulation  9.1.19.3 Filter Geotextile  9.1.19.4 Water insulation membrane  The work shall consist of supplying, laying and finishing complete insulation and roof coverings and  shall include the provision of all necessary skirting, copings, flashings etc. On completion, all roofs  shall be left sound and watertight and in neat and clean condition. All roof finishes shall be carefully  worked or fitted around pipes and openings. Roofing systems shall be in general the “inverted roof“ or “protected membrane roof system“ where  the waterproof membrane is laid directly onto the structural slab and the insulating layer is then laid on  the membrane and protected by a layer of files. If heavy snowfall is expected at the project area, roofs shall be designed as timber or steel roofs and  covered with aluminium trapezoidal sheet cladding or aluminium sandwich panel.  Any special working details prepared by the Contractor must be submitted to the Engineer for approv- al.  The structural slab or surface screed on it shall be primed before application of the membrane in ac- cordance to the manufacturer’s instructions. The insulation layer shall have a minimum density of 35  kg/m².  The waterproofing system shall be of approved type and manufacture. The waterproofing system shall be suitable for prevailing climatic conditions and shall be capable to  withstand local weather conditions especially as regards to high temperature difference between day  and night, high humidity and heavy rains. The waterproof membrane must have a mineral fibre sur- face.  The material shall have resistance to Ultraviolet light, chemical attack and experience no significant  change to its physical, chemical or engineering properties under the influence of sulphates, chlorides,  acids and alkalis in the forms and concentrations in which they are present in soils and ground-water  to be found in-place. The material shall have proven resistance against bacterial or other microbiologi- cal attack and shall perform according to its specifications at working temperatures between 5 and  45°C. Temporary exposure during construction to temperatures up to 60°C shall not permanently im- pair the material. Filter fabric shall be supplied in rolls of at least 2m wide and shall unless specified otherwise be  lapped in both directions at 0.3m wide. Roll lengths of the fabric shall be such as to lay complete in  one operation without jointing, each of the various sloping and horizontal lengths.  The water permeability of the fabric shall be greater than that of the soil it is protecting while the mesh  size shall be smaller than the sieve size passed by less than 10% of the soil particles. The weight of the  fabric shall be at least 240g/m².  On inverted roof, water insulation shall be made by two layer of water insulation membranes. First  layer shall be 3mm thick fibreglass retrofitted and second layer 3.3mm polyester rock wool retrofitted,  one side mineral glazed.  9_Vol3_d4.3_Section 9 building works_en_GIR_rev6.docx 