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Any structure i.e. the house has to deal with wind, sun, rain and snow. These combinations affect the structure. The structure as constructed is a relatively free terrace or top level. Here it also receives maximum direct effects of the sun and rain. The external facade of the building i.e. the exposed side in elevation attracts varying wind, sun and rain. Due to the behavioral difference of action on the ground floor and at terrace level, some kind of movements always takes place in the structure. Generally they are within limits for most of the structure. However, it is a common observation that weather damage is more at the upper storey as compared to lower storey.
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The building needs the use of several materials for its construction. Each one has different properties. Depending on its basic quality, the manner in which it constructed, nurtured and protected the variation leads to separation cracking between two surfaces, which is a common experience in present-day construction.
There are three stages where actions need to be taken:
Proper detailed planning and designing by architect, structural designer, detailed engineering for preparing detailed working drawings, specifications, estimates for inviting tenders is must. Engineers / design consultants are to prepare various service systems including designing building facades in such a way so to keep off water and to allow easy flow.
Technical investigation of underground soil, site survey / levels, past data of stagnation of water on low lying area needs to be done prior to commencing design.
During construction proper management, supervision, monitoring, and total quality control is required by carefully selecting reputed contractor and application of efficient project management and total quality control as per approved architectural drawings, engineering details and specifications.
Construction of a building is a joint effort of many and waterproofing of it, is an ultimate test of the work done by all of them. Any mistake in the design or faults made during the construction process, come to light in the form of leakage.
When the waterproofing work is in progress, it requires constant alert and patience. The work should be carried out meticulously, and with attention to every single detail.
Reasons for Failures of Waterproofing Treatment:
Improper diagnosis of the leakage problem:
The source of leakage is not always located near the visual marks of it. After entering the body mass, the water moves in all directions. One has to identify the source visually. It may not be the place where actually you see dampness or leakage. It might have entered from somewhere else.
The study of construction sequence and activities will assist in arriving at the conclusion. The information given by the people making use of the premises helps in detecting the fault.
Electronic probing instrument and gadgets prove useful in the detection of the underneath water source.
On collection the data from the different sources the conclusion should be drawn and accordingly the material and the method to be used for the treatment should be decided. Any mistake in the judgment may result into the failure of waterproofing.
The care of the envelope:
During waterproofing punctures after repairs or modifications on walls, plaster or any part of a building, is left carelessly without cover treatment on it. e.g. During external plaster, the holes provided in the walls for scaffolding are never filled properly nor cured after filling.
Waterproofing treatment cannot be carried out in patches. It has to be all over on the exposed surface of a structure. Dependence on the local or partial treatment should be avoided.
Wrong Selection of the material:
A wrong selection of the material will certainly lead to the failure of the treatment. In the market many chemicals are available for the purpose; however, their use is specific. When these chemicals are used in a wrong way at wrong places, the treatment is bound to fail, in short time.
In larger structures when expansion joints are provided with the material used to cover the gap should be flexible enough to stretch along with the bodies. It should also come back to its original state when required. If the material does not keep pace with the movement of the structure then soon it will fail. The filler material has to be flexible. Application of rigid compound will fail in this area.
Again a point where two or three different types of building materials form a joint, it is termed as a composite joint. At such place the waterproofing material used, has to be compatible with all the surrounding materials or else the treatment will fail. For example, waterproofing of aluminum or wooden window frame fitted in the wall.
Epoxy is formulated in part A and B. With every manufacturer their proportion differs. When they are mixed in the right quantity, they form a third product which is completely different from the first two. Same way, the certain products in polyurethane requires the catalyst to begin the chemical reaction. Till then the product is not effective if the manufacturer’s instructions are not followed thoroughly then the product will not perform and will malfunction, resulting in a failure of the system.
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Failure in carrying out proper preparatory work:
Before commencing waterproofing treatment it is essential to do preparatory work, such as cleaning the surface of dust, filling all the holes, cracks and cavities, repairing the damaged portion, relocating the embedded pipes, removing the existing material used in the earlier treatment, applying recommended primer, core cutting in concrete made for the pipe fitting, etc. needs to be properly finished. Any lapses in systematic preparatory work will lead to the failure of the system.
Usage of incompatible materials:
Various integrated systems and products are used together to achieve combine waterproofing effect. The products which are used may be solvent based, oil based or water soluble. These products do not always compliment with other materials when used in combination. Certain products might have been used earlier, or might have to be used at a later stage. They will not form one monolithic treatment.
Tar with its characteristic does not have good bonding with certain polymeric or rubberized products. If such products are used in combination, the system fails.
When large size unprotected openings provide in the direction of the rain, then the water easily entering into the building. The designer has to consider the junctions carefully, and the terminations are coming across. The provision of flashings, mouldings and drops slopes needs meticulous planning. Staircase landings should be well protected from spilling over of rainwater through the ventilation openings.
The members of the R.C.C grid designed with joints and junctions are required properly covered. Such places are critical for the water to get into the body mass. The designer should visualise these areas and should provide remedial solutions to the forthcoming problems. Old palaces, monumental buildings are decorated with fine intricate designs. The ornamental design is not only for the aesthetic purpose, but it is cleverly moulded to channelize free-flowing water into the direction of the ultimate drainage system. Waterproofing can be achieved even by intelligent devised, design system.
Lapses in the supervision by key post overseers like architects, engineers, contractors, and owners:
Any mistakes, in the detailing of the drawings, or during the execution of the job, will lead to the failure of the system. The careful supervision throughout the time, when the work is in progress, is most important.
On the extremely porous surface, when large practice size coating material, is applied, then it does not penetrate. The surface gets heated due to the sun rays and the air trapped in the cavities and hairline cracks expand to form the blister on the surface and that delaminates the film.
Mistake in underlying the detailing of junctions and terminations:
One uniform treatment cannot be used at all places on the surfaces. Treatment at the junction and the transition of the plane had to be different than the one given on the plain surface. The drops, openings, flat surfaces should be properly safeguarded by providing flashing, moulding, slopes, etc. Areas with large span require typical treatment with the breaking of continuity and tolerance for the movement, failing which the surface will crack. Mistake in locating critical area will lead to the failure of the system.
Failure in adhering to the manufacturer’s instructions:
This is very important. Most of the modern chemicals used in waterproofing have polymer as a base. These chemicals are designed to perform different tasks for which they are made, and therefore their usage becomes very critical. Many chemicals have their own pot life or shell life i.e. they need to be used within the certain time after opening the container. If not done, it will lose the property. Similarly, if it is not mixed properly, it may not work.
There is not much scope for the corrections, once the work is done. Rectification means the waste of money, time, material, and labour. Therefore it is essential that all the supervisory level personnel are attentive in carrying out their duties carefully at every level of the work.
Above given are few reasons, for the failure of waterproofing system. The list is not exhaustive. Combined efforts are required in overcoming the failures. Much more can be accomplished as result of everybody’s devotional participation connected with it.