ROOF WATERPROOFING SERVICES
Chemicals range of waterproofing products and systems that include specialised bituminous sheets, liquids, putties, cementitious based products and silanes. Bituminous sheet products are used to waterproof flat roofs, basement walls and to line earth dams and canals.
Liquid systems and putties including acrylics, solvent-based bitumens and water-based rubberized acrylic modified bitumens which are used to seal parapet walls, small flat roofs, roof bolts, flashings and ponds.
Cementitious slurry products are used to waterproof basements, foundations, tunnels, retaining walls, brickwalls and other underground structures. The silane systems are used to prevent water penetration of brick and natural stone.
SUBSTARTES AND FALLS
Boards laid to minimum falls of 1 in 60, the strength and thickness as per engineers specification. The moisture content is not to exceed 7% prior to torch-on applications.
Should light weight screeds be employed an additional sand cement screed is to be placed on top of the light weight screed, the strength and thickness as per engineers specification. Under no circumstances must the torch-on material be applied directly onto the light weight screeds.
Special care must be given to all expansion/construction :
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Surface areas should be dry, clean and sound, free of voids, sharp protrusions or contaminants.
1. NEW ROOFING : Prime all surfaces with bitu.®prime, including all verges, and around outlets and protrusions and allow the solvent to flash off. Extremely porous surfaces should be reprimed.
2. REJUVENATION : Strip existing waterproofing before priming all surfaces with bitu.®prime, including all verges, around outlets and protrusions and allow the solvent to flash off.
Apply the first layer of 3 Ply malthoid or Index Rollbase fastened to the boarded surface. The 3 Ply malthoid or Index Rollbase must be applied providing for 100 mm side laps and end laps.
The mechanical fasteners anchoring the 3 Ply malthoid or Index Rollbase are to be spaced at intervals of 300 mm centres and shall be fixed incorporating 40 mm diameter washers.
A gusset section of unigum 4 mm is to be torched to the parapet to a minimum height of 100 mm up the parapet, brought down across at least 100 mm over the 3 Ply malthoid or Index Rollbase.
Apply a second layer ensuring that the second layer is fully bonded by means of ‘torchon fusion’ using propane gas, having side and end laps of 100 mm and 150 mm respectively. The rolls are to run parallel to each other, centrally staggered to prevent joints overlapping.
Additional gusset sections of 150 mm minimum up the parapet wall and dressed 150 mm minimum over the main waterproofing, Index Fidia MS 4,5 kgs.
All plain exposed surfaces are to treated with 2 coats of silvakote as protection layer against UV rays. The coating should be applied 6 to 8 weeks after torching process to allow the surface to oxidise slightly thus providing good adhesion of the coating.
Counter flashing over the balance of the parapet is recommended using super laycryl or super laykold.
Specific attention must be given to the detail work when waterproofing the outlets to prevent ingress of moisture