High-rise buildings need special attention when it comes to waterproofing as the challenges inherent in them are peculiar in nature. Unfortunately, there is a lack of knowledge on the remedies and products available in the market as water- proofers continue to rely on age-old methods. In this article, experts from leading waterproofing companies share with Meghana Raut, their knowledge and experience in waterproofing concrete structures and suggest some of the latest solutions.
“One of the most important aspects of a structure’s design and construction is the waterproofing membrane that covers it. External structures are often severely damaged by intense heat and humidity followed by frequent heavy rainfall. Due to this, in many structures, cracks, water leakage, and seepage are typical issues,” says Aarti Harbhajanka, Co-Founder, Primus Partners.
Despite the training by numerous institutions, there still seems to be a shortage of labour; as a result, it is difficult to control the quality of craftsmanship and the developer is to blame.
Aarti Harbhajanka, Primus Partners
“Even if one pipe leaks, there will be multiple seepages going into different buildings. Building damage and faults can have detrimental implications for all parties, whether they do so directly or indirectly. In addition to endangering the safety of the residents, it could also degrade the building’s visual appeal. There is no reason why the residents of a building should avoid taking the necessary precautions to maintain their outside walls, even while the cause of this issue may be the builders’ lack of foresight or the contractors’ adoption of a quick repair,” she adds.
“An issue faced by high rises is the tilting they experience due to wind pressure. Tilting demands use of waterproofing compounds with good elongation index and flexibility,” explains Kunjan Popat, Founder, Trifix Technologies and General Secretary, WAI. “Another serious concern is the basement because as buildings go higher, basements go deeper. When basements go deeper, a lot of construction joints appear, and the building will undergo uplift pressure, settlements, hydrostatic pressure, seismic movements, etc.”
He adds, “In coastal cities like Mumbai, basements are also subjected to sea water ingress. There have been many cases where basements of some buildings have been closed to public access because of water seepage. Also, if there is no space between the sheet piles and the retaining wall, waterproofing becomes necessary so that the water does not fill the space.”
According to Harsha Kavi, Regional Product Segment Manager - Waterproofing/Sealants, Fosroc, exposure to ground water pressure combined with quality of urban soil contamination by surrounding effluent release necessitates high quality waterproofing. “So, one cannot afford to apply underperforming material for waterproofing or be negligent in the application quality.
Harsha Kavi informs that the quality of construction of high-rise buildings has to be extremely good in terms of specifications, materials etc. What’s more, specifiers need to have full information on the merits and demerits of waterproofing systems, accessories, and appurtenant systems that augment high-end waterproofing materials. “Since high-rise buildings have a lot of inhabitants, to reduce the carbon footprint, one must provide vegetated landscaping; this, in turn, needs the right waterproofing sealing system that can bear the brunt of the water laden soils and the fertilizers used for growing the vegetations.”
“Waterproofing for such situations demands very durable systems which come with a higher cost. Waterbodies may be at the podium level or on the roof and thereby contained within the building. Waterproofing thus becomes a challenge in terms of the durability of the waterproofing system. Wind-driven rain experienced in high-rises necessitates waterproofing and sealing of window perimeters and service areas. The exterior walls of high-rise buildings are also inaccessible for re-coating and maintenance, which can be problematic,” he adds.
“One peculiar issue for undertaking waterproofing in high-rises is the Lifting of materials to top floors. A single lift is used by multiple agencies due to which time slot given to one agency is very limited each day which increases the Labour cost as well as delays the material shifting. Also, waterproofing work has to be done perfectly, and any pause in the work can lead to faulty waterproofing,” says Ramendra Bahadur Sinha, Founder & MD, Agrani Group.
Qualified Waterproofing Expertsor Professional Agencies should be appointed to find the root cause and Propose tailormade waterproofing system suitable for the job. Waterproofing is not a Product Application alone, it’s a system with lot of steps involved.
Ramendra Bahadur Sinha, Agrani Group
Sameer Karkhanis, Founder, Odd Jobs Waterproofing, enumerates the many operational challenges in high-rise buildings:
- Elevation/projections of the building are such that it is not feasible to install scaffolding, material lifts, etc.
- Working while retaining the exterior look of the building.
- The cost factor is higher hence service societies and maintenance departments don’t sanction the amount needed for quality work, and look for cheaper options, with the result that cracks, and seepages reoccur.
- Property buyers have already paid many other charges and are reluctant to pay for any extra work.
“The first mistake an owner makes is in not hiring a waterproofing consultant. Waterproofing is a full-time specialized profession and should never be carried out by an unprofessional. You might end up using inappropriate products for the waterproofing job,” warns Sameer Karkhanis.
“Other cause are additives and admixtures not used, or, if used, then added to concrete without proper know-how. Wrong diagnostics by pseudo contractors leads to wrong remedies and subsequently failure in stopping the leakages. Professional water-proofers not only undertake full responsibility for the work done, but also give warranties/guaranties for an x-number of years. Another issue is the lack of importance given to surface preparation, which is equally important. It is said that a good beginning is half the work done!” he adds.
Waterproofers are reluctant to adopt new technologies since, according to them, the age-old techniques are working just fine.
Kunjan Popat, Trifix Technologies & WAI
According to him, use of old, stereotype practices to solve concrete leakage will not help in solving the current issues that come up due to modern, complex designs. “Architects want their projects to look the best with unique designs and elevations. The beautification of a building’s exterior can only be retained for a long time if a waterproofer is hired at the planning and designing stage; however, this does not happen due to the lack of attention given to waterproofing.”
“Another issue is of water ponding on concrete surfaces that are not flat enough or where there is an inadequate slope. Even if concrete is freshly laid, preventing water ponding is very important before waterproofing work begins by checking if there are any structural defects, shrinkage, cracks etc. When it comes to basements and retaining walls, using cheap chemicals can put the entire building in danger. In case of landscaping, swimming pools, and fountains, unethical waterproofing practices and use of low elongation chemicals and membranes can create trouble in the long run.” he warns.
Joints: the vulnerable places
“An add-on factor impacting waterproofing is the reluctance in adopting newer technologies. Waterproofers like to stay with the age-old techniques since according to them, they are working just fine,” says Kunjan Popat.
“For the common man, waterproofing is simply applying a solution with a brush and the work is done!He is influenced by TV advertisements on the readily available products in hardware shops. But the fact is that a qualified Waterproofing Experts / Professionalsshould be appointed to find the root cause and solve it because Waterproofing is a term used for system application not a Product, adds Ramendra Bahadur Sinha.
Kunjan Popat emphasizes proper joining of HDPE membranes used in basement waterproofing as an essential measure. This has to be done using heat treatment. If EPDM membranes are used, then good solvents have to be used to ensure waterproof joints. Wherever construction joints are present, water stoppers have to be compulsorily used, since the joints are the most vulnerable places where seepage can penetrate from.
Agrees Harsha Kavi, “Almost 99% of the failures in waterproofing happen due to the 1% of openings in transitions and poor detailing that are not sealed effectively. Before taking up waterproofing, a thorough understanding of the structural and architectural detailing are a must. Lack of proper detailing is one of the major factors for waterproofing failures. Proposing ‘fit to purpose’ waterproofing is the only way. For instance, the tensile strength of waterproofing membrane should be high.”
Says Aarti Harbhajanka,“Building flaws are a natural result of poor craftsmanship. The weakest link in every structure’s combination is its joints. When leaks occur, their sources are frequently close to where the building fabric first failed. Structural instabilities can be one of the major reasons for water seepage if waterproofing is not done properly. Cracks, a deteriorating waterproofing system, concrete honeycombs, and construction joint failure are the main causes of waterproofing failures in concrete buildings and structures.”
The first mistake an owner makes is in not hiring a waterproofing consultant. Waterproofing should never be carried out by an unprofessional as you might end up using inappropriate products.
Sameer Karkhanis, Odd Jobs Waterproofing
“Improper plumbing is a common issue of seepage in high-rises.To ensure good joint sealing, firstly, the core cutting for the pipe slots has to be sufficient all around the Pipes to accommodate the sealing compound and the cutting has to be uniform. Sometimes bores are cut with the help of chisel hammer in improper shape and pipes cannot be properly sealed and above that waterproofing cannot be done adequately. Another issue is that sometimes two to three pipes touching each other and passes through a single bore which is actually a wrong practice and causes a major reason of leakage. This also hinders the application of waterproofing to the entire circumference of the joints,” says Ramendra Bahadur Sinha.
Who bears the responsibility?
The experts attribute the cause of failure to improper selection of waterproofing system, not carrying out proper preparatory work, use of incompatible materials, design flaws, and co-ordination issues. According to them, the applicator and the product owner are responsible for waterproofing execution, incorrect diagnosis of leakage problems, faulty external plastering, and lack of effective monitoring post the application.
Says Aarti Harbhajanka, “In most cases, waterproofing is inexpensive compared to other project costs. Many contractors are attempting to reduce the cost of waterproofing membranes. Plus, there is a short supply of workers in the industry due to the building industry’s explosive rise. Despite the training initiatives run by numerous institutions, there still seems to be a general shortage of labour, both skilled and unskilled. As a result, it is now difficult to control the quality of craftsmanship, and the developer is to blame.”
“However, post the advent of RERA, in cases of any structural defect or any other defect in workmanship, quality, or provision of services, the governing body will hold the promoter or the developer responsible to make amends within five years of handing over possession,” she adds.
“When it comes to the governing body, no such Codal regulations are in force which focus on waterproofing. Architecture fraternity focusses only on building design, but not on the waterproofing aspect. Ideally, the rainfall facing side of buildings should have least number of openings,” says Kunjan Popat.
Types of waterproofing solutions in the market
According to Harsha Kavi, in every structure, depending on the exposure conditions and serviceability requirements, and in every part of the building, different kinds of waterproofing systems are specified, as shown in the table below:
Sameer Karkhanis elaborates, “Epoxy-based waterproofing is done by using the injection method for concrete waterbodies and basement retaining walls. Hot air bitumen membrane sheet and tarfelt should be used on the exposed areas. Unfortunately, these are wrongly used on concrete surfaces where materials fall over it. In polymer coating, cement may or may not be added. Thsese cementitious coatings are diluted with either polymer or polyethylene. What matters here is the quality of the product, its viscosity and elongation properties, and knowing how to apply the product. PVC membranes used for installing in water bodies, basements, and retaining walls, should be installed correctly and by using the right methodology.”
The quality of construction of high-rise buildings has to be extremely good in terms of specifications, materials etc, and specifiers need to have full information on the merits and demerits of waterproofing systems, accessories, and appurtenant systems.
Harsha Kavi, Fosroc
Explains Aarti Harbhajanka, “There are different types of waterproofing solutions: cementitious waterproofing is inexpensive and simple to install, but it lacks flexibility and cannot withstand joint or crack movement. Thermoset and thermoplastic polymers are used in sheet membrane waterproofing. Thermoset membranes are sheets of rubberized performance material that can be vulcanized, non-vulcanized, or both. It is necessary to apply for a damp proof course. The appropriate corrective measure is to replace the damp-proof materials.”
“In order to accomplish a totally effective treatment, drilling should be used. Epoxies can close gaps while maintaining load-bearing capacity. It has numerous strong compressive points. Expansion and control joints must be added if the crack is likely to expand or move in the future; otherwise, the treated crack might permit movement. Preventing moisture from penetrating beneath concrete pads and causing them to heave or sink will keep the junction waterproof. Prevention is always better than cure, and timely waterproofing measures will prevent a great deal of trouble in the future,” she adds.
“There are a lot of options available in the market, Majorly double component acrylic systems for wet areas are recommended. The choice of either depends on the budget of the client. Polyurea/ Polyurethane-based coating arethe best for Podiums & Terraces. For the raft areas, these days good HDPE membranes are available with thickness varying from 1.2mm to 1.5mm,” explains Ramendra Bahadur Sinha.
Anil Banchhor, MD & CEO, RDC Concrete: “Waterproofcrete is a specially designed concrete which has reduced water permeability for the same grade of concrete generally used. It has specially tested admixtures, which have been tested to give the highest performance in terms of reduction in water permeability. Most of the integral waterproofing solutions available for concrete have their own unique properties, which, however, are not meant for Indian conditions, besides which, they are costly too. Our R&D has rigorously tested most of the methods, both on lab models and prototypes. Since we don’t have a tie-up model with any manufacturer of these chemicals, we have the liberty to choose the best performing solutions for waterproofing. In my view, the solutions offered by Waterproofcrete are the most efficient.”
Sameer Karkhanis, Odd Jobs Waterproofing: “Crystalline waterproofing comes in single component or 2 components and is applied mostly on poured concrete surfaces to protect them from dampness. It can be applied on concrete slabs of a terrace, bathroom sunk, water bodies, places below the ground surface, etc.
Alkaline admixtures and glass fiber or liquid admixtures should be used strictly under a waterproofing consultant’s or an applicator’s supervisor’s guidance and while pouring concrete by RMC or a hand mixer machine. This will protect the areas from voids, porosity honeycombing, concrete shrinkage, crack formations, and also give excellent protection to the reinforcement.
Water stoppers or swelling bars are used to break the flow of water seepage and are placed in position during the construction phase. These should be used in areas where concrete joints are present and particularly on steel bars before pouring concrete, or after an earlier poured concrete has got set. Its main utilization is in basement walls, retaining walls, shear walls, and in water bodies. Flashing tapes can also be used similarly on horizontal and vertical joints.
Injection grouting whether it’s cementatious, epoxy or PU Foams should be used from positive sides in construction rather than from negative sides. Silicon coatings, PU, high elongation polymers, and bore packing methods ensure good waterproofing in a building.”
Ramendra Bahadur Sinha, Founder & M.D, Agrani Group: “For rainwater related dampening, I would suggest injection grouting. For retaining walls, Podiums & other heavy concrete structutres, where positive side waterproofing cannot be done, negative side waterproofing methods can be adopted, especially in places like basements andunderground car parking areas.”
Harsha Kavi, Fosroc: “Remedial waterproofing in roofs is by far the most complicated. Roofs are usually crowded due to installed units for air conditioning, plumbing pipes fixed onto the roof surface and parapet walls, etc. Sometimes, steel fabricated over-bridges are erected over roof areas, where large sized pipes run over the roof surface. All these need to be relocated and lifted well above the roofing surface or parapet before one can start surface preparations. In domestic situations, the relocation may be far easier, which the waterproofing contractor can take up as a part of his remedial job.
Loose plasters and cracks in surface of the roof need to be exposed with mechanical means along with high pressure water jetting, etc. Once the bare surfaces of the walls and roofing surface are exposed, there could be signs of corrosion seen. Generally re-roofing requires quite a bit of civil work and good technical understanding, which sometimes may be outside the scope of the waterproofing job, that requires to fix the substrate issues. In short, there is no straight answer for recommendation of the waterproofing materials, as it is always subjective. A tailored solution needs to be worked out to see that the remedial waterproofing is effective and long lasting.
In wet areas like bathrooms, a superficial remedy must never be adopted. It is essential to remove tiles. The basic waterproofing must be done by way of brush applied cementitious coatings after repair of plumbing and sanitary fittings. In most situations, old, corroded GI plumbing has to be replaced and relocated in the bathroom. Bathroom renovation and its interiors will dictate the waterproofing and tile fixing specifications with more modern fittings. In case a bathroom’s base is leaking into the neighbour’s bathroom below, PU Injections may be most effective solution for drip leakage.
For basement walls, good materials are available to arrest mild dampness in the interior side of concrete basement walls. Once a dry surface is achieved, it will be safe to coat these walls with decorative paints. When it comes to leaking podiums, it is ideal to strip the entire area on top of a leaking podium and after surface preparation and repair of the deteriorated area. Depending on hard scaping or wet scaping design, appropriate membranes such as polyurea treatment is suggested. The existing expansion joint profiles need to repaired and treated, and then filled with a low modulus, high MAF sealant. The sealant all along the podium surface will need to be covered with an aluminum channel cover, riveted over, to protect the sealant from the landscaping and soil overburdens.