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By J.J. Shah

There is hardly a building in Mumbai, which does not leak. Is there no permanent solution to this problem? Can taking guarantees from contractors solve this problems? Mr. J.J. Shah deals with this topic in the article in Nut-Shell which haunts all of us day in and day out. Mr. Shah has authored a book “ A Handy Guide to Repairs, Rehabilitation and Waterproofing of Reinforced cement concrete structures” which deals with the A to Z of restoration of Building including waterproofing. Presently he is busy writing a book or Durability of RCC buildings mainly to help small building to achieve purability.
INTRODUCTION
It is possible to build RCC structures where there is NO LEAKAGE. In fact any waterproofing treatment provided should be considered as a secondary line of attack. In short a New RCC structure should be built to DURABILITY PARAMETERS where will not stagnate anywhere and that the water will not seep into the property. This is a subject in itself and we will take up this some other time. The present article deals with the WATERPROOFING OF EXISTING RCC building which have severe LEAKAGE problems.
APPROACH
Can anybody claim that he is A LEADAGE expert? Can one particular treatment get you rid of Leakages? Can taking guarantees solve the problems? Answer to all the above questions is a big No. Then how do we tackle this menance? We can successfully tackle the LEAKAGES by proper APPROACH to the problems in a logical and scientific manner.
DIAGNOSIS
Explain your leakage problems to your expert in detail. When a patient tells symtoms of his illness to his family doctor properly the doctor is in a position to give him proper treatment, same is true here. Check up if the leakage observed is: i) All the 365 days of the year is this observed. ii) During changing of tiles of the floor/ During repairs and Rehabilitation work/During renovation work.
This is the First step to-wards effectively attacking leakages.
SOURCES OF LEAKAGES
There are innumerable sources of leakages. The second step is to identify the source. The source of leakages are listed below. 1) Sub soil water rising by capillary action. 2) Cracks in the external plaster. 3) Vegetation growth. 4) Pockets, Crevices formed in the External wall during renovation work taken up by individual flat owner e.i. Fixing of stone chewkets to the windows, Fixing of Air conditioner in the wall, Changing of drinking water lines. 5) Separation Gaps, between partition brick walls and the beams and the columns. 6) Deterioration of Brick-Bat koba with or without china mosic chips. 7) Over head water tanks. 8) Parapets specially brick parapets, from cracks, pockets formed due to Antena inserts, holes formed for fixing of water lines all along the parapet etc. 9) Plumbing lines.(i) From damaged, leaking and or rusted pipe-lines. (ii) Rain water pipes are not properly pulled beyond the inside face of the parapet. This is the common phenomena all over.
(III) Rusting of concealed pipe lines and or from joints of concealed pipe lines. (10) Chajjas, Top Balcony slabs, Top of stair case Block, Top of Lift room and entrance canopies. (11) Plantation of plants against the external wall. (12) Washing of floors by pouring water this leads to leakages through the tile joints. (13) due to condensation (14) from expansion joints. (15) Humidity (16) Leakages from Top flat toilet blocks / Mori Traps to Lower Flats. This is a very common problem faced by many. (17) From construction joints (18) and so on.

Solution
Once we know the symptoms and the sources of the Leakages it is easy to tackle the Leakage problem.
1. Sub soil water rising problem: Author has successfully tried to tackle this problem simply by grouting with cement slurry with acrylic polymer bonding agent and with super plasticizer. This is done both from outside all along the periphery of the building and from inside the flats just above the skirting. In this method no damage is done to the structure or to the décor and further this helps in providing STABILITY against Earthquake forces and also stops vibrations experienced due to taffic to the building.
METHODOLOGY: The client must study the methodology specified and must not relax by taking guarantee. To substakist this point of view following few examples are given.
TERRACE WATERPROOFING: i) Generally the brick-bat koba with or without china mosic is replaced without studying if the leakages are from any other sources also, Again after replacing the brick-bat koba with or without cine mosic the rain water pipes are not pulled beyond the inside face of the parapet. This results in rain water percolating in the property and the author has come across building where the external walls are acting as pipes resulting in leakages/dampness in the flats from top storey to ground floor and Leakage/dampness which did not exist earlier. ii) Is it proper to provide a New RCC slab over the existing slab when the condition of the existing terrace slab is bad? The correct solution is either to repair and rehabilitate the existing deteriorated slab replace it by New if or it is beyond repairs. But definitively not by providing a New slab over the existing deteriorated slab which is detrimental to the structural, to the occupants and is totally a wrong solution, a watch for any such solutions which can result in a MISHAP. The author has the knowledge of a terrace slab which collapsed along with the new waterproofing system provided to it in shoot time obviously this was the wrong decision to provide new waterproofing to a deteriorated slab without rehabilitating the same.
OVER HEAD WATER TANK: Here again the author has come across new RCC slab provided over the existing deteriorated slab of a tank.
AGE OLD WATERPROOFING SYSTEMS: These are: i) Bitumen, this has organic material which decays with time. ii) Brick, bat koba with or without china mosic. iii) Farsi type box waterproofing.
All the above systems have inherent problems and have short life and delay the project. The best solution which the author appreciates is flexible membrane waterproofing system which becomes part and parcel of the RCC member and is easy to apply has long life.
GENERAL: The author has put up the general scenario of present day way of tackling, Leakages with emphasis on guarantees. Leakages are from many sources and some are only during monsoon and some are observed during renovation. It is absolutely necessary to make an attempt to find the source and the time of the leakages and to device a Methodology after proper study. This is a VAST subject and the author has cautioned in a Nut-shell how to tackle this problem. This is the blue-print to proceed with the solution with help of your expert.