Waterproofing

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Waterproofing

  • Conventional Waterproofing :

Waterproofing of terraces is carried out as described below and in the same sequence:

  • Break and remove old waterproofing treatment from terrace slab.
  • Remove the plaster from the parapet walls etc. up to at least 300 mm. height from the slab top level.
  • Thoroughly chip and roughen exposed concrete. Rake out the joints of brickwork. Clean with wire brushes and wash thoroughly with plenty of water.
  • Any loose patches in base concrete shall be first repaired. If any steel is exposed, clean it and apply a protective coating. If any cracks are seen, open and seal them as directed by the consultant.
  • Cut in a form of “V” the junctions between walls and floor. Fix small pieces of brickbats along with 20 mm (3/4”) metal for coving of Watta (rounding) at the bottom of parapet wall.
  • Add one bag of cement in hundred litters of water. Stir the mixture to get consistent cement slurry. Spread this slurry on terrace and allow it to penetrate uniformly over the cleaned surface. Use well burnt brickbats for terrace waterproofing.
  • Fix (line dori) in a slope 1:125 starting from the lowest point from rainwater down take and by keeping 65 mm (2.5”) minimum thickness below rainwater outlet.
  • Fix brickbats in cement mortar layer of 1:6 proportion in a slope of 1:125 with waterproofing compound. Fill the cement mortar 1:4 with waterproofing compound in brickbat joints. Block rainwater outlet with gunny bag to avoid entry of cement slurry into it.
  • Cure the brickbat coba coat for atleast seven days.
  • Lime mortar made from lime and fine sand in proportion of 1:5 is spread uniformly on the surface of 20 mm to 25 mm uniformly. This bed is left to harden for one day.
  • The design pattern if any is to be marked over this bed with the use of cotton line string. A splash of water is sprinkled lightly on this bed and very little dry cement is spread for work area of next 15 minutes. Then pieces of China mosaic are pressed and filled in position. The joints between these two pieces shouldn’t exceed more than 3 to 4 mm. These pieces are hammered with wooden mallet to achieve uniform surface. Make the projected edge (kani) between the parapet plaster and the watta on second day.
  • The surface is cleaned with saw dust to remove excess cement sticking to the glazed China mosaic surface. If surface is not cleaned thoroughly by this method, then the same shall be cleaned with dilute acid after one month, as directed by the consultants. 1.13. Completed work is then cured for 15 days by ponding method.
  • Chemical Coating Waterproofing
  •        Providing and carrying out water proofing works for terrace horizontal surfaces with Elastomeric waterproof liquid chemical coating of approved make comprising the following specifications.
  • Carefully preparation of the existing surface of terrace including watta by grinding or mechanical means to make the surface fungal free, rough to form grip for coating, free of dirt particles, etc., uprooting plants/ shrubs grown on the surfaces, filling the hole if formed any with ready mixed plaster, cleaning the terrace surface by water jet spray from dust or any other loose particles, foreign materials, grease, oils etc and treating the surface cracks by making a ‘V’ groove of required depth and width, cleaning the same and entire terrace tile joints filling with waterproof sealant grout of approved make up to the satisfaction of engineer and as per manufacturer's requirement and application of waterproof primer coat of approved make.
  • Providing and applying three or more coats of elastomeric chemical waterproof coating of approved make as per manufacturer's specification to be applied in uniform layer mechanically or manually applied over terrace surface and watta. WP coating shall overlap minimum 150mm above watta to existing plaster surface of parapet walls. WP coating shall be mixed, prepared and applied strictly as per manufacturer's specification. The mixing methodology, mixing proportions of the material, surface preparation and application of the coating shall be done, strictly, as per manufacturer's specification and as directed by engineer. After completion of WP coating the treated terrace surface shall be tested with water ponding for 72 Hrs over entire treated surface area.
  • Waterproofing of Chajjas / Balcony / Tank Top:
  • Clean the top of the chajja and chisel extra mortar if any.
  • Apply thick cement slurry over the top of chajja.
  • Apply 1:1½:3 metal screen or brickbat coat.
  • Making rounding of 6” radius on the wall (watta) at the junction of chajja and wall of the building.
  • Cure this coat for seven days.
  • Apply finishing coat with C.M. 1:4 with waterproofing compound.
  • Provide drip mould at the bottom edge of chajja along with finishing coat.
  • Apply cement slurry with water-proofing compound for smooth finish (ghotai). Polish with metal float and make impression by 2mm diameter cotton line dori for avoiding cracking.
  • Cure the water-proofing for at least seven days with soaked gunny bags.
  • Tank Internal Waterproofing Tank:
  • Waterproofing of tank is carried out as described below and in the same sequence.
  • Break and remove old waterproofing treatment & plaster if any.
  • Thoroughly chip and roughen exposed concrete. Clean with wire brushes and wash thoroughly with plenty of water.
  • Any loose patches in base concrete shall be first repaired. If any steel is exposed, clean it and apply a protective coating. If any cracks are seen, open and seal them as directed by the consultant.
  • Cut in a form of “V” the junctions between walls and floor. Fix small pieces of brickbats along with 20 mm (3/4”) metal for coving of watta (rounding) at the bottom of wall.
  • Add one bag of cement in hundred liters of water. Stir the mixture to get consistent cement slurry. Spread this slurry on slab and allow it to penetrate uniformly over the cleaned surface.
  • After drying, applying two component (mixing ratio 2 A: 1 B)) Antibacterial food grade coating inside drinking water tank in two coats with time interval of minimum 8 hrs.
  • Completed work is then cured for at least 03 days by ponding method.