Waterproofing in a Building – Construction Solution

Types of Waterproofing the Building

Need & Importance

It is a dream for everyone to own a house of their own, even better when one can witness the foundation being laid and see it take shape in front of them. But there is a common problem for all – water seepage due to bad waterproofing.

It hollows the whole structure of the building, causes long term problems ultimately affecting the life of the overall construction. This blog is a one stop solution for all types of waterproofing.

It will guide you through all the precautionary process, products and procedures of the types of waterproofing in construction of your dream house.

• Foundation Waterproofing
• Basement Waterproofing
• Bathroom/Kitchen/Balcony/Chajja Waterproofing
• Terrace -Garden/Swimming Pool Waterproofing

Building Foundation Waterproofing

The foundation is the most important aspect in a building structure, one should take all possible measures to ensure its  longevity. The construction is built upon the foundation and these can be of multiple types.

The strength and life of the house is directly dependent on the the foundation. The most prominent and concerning  problems – dampness and water logging. Moisture in the soil around the foundation which later seeps into basement and provides an ideal environment for mold formation.

Mold Formation on Exterior wall due to water.

Waterlogged Construction site.

Precautions to take before construction of Foundation

Water logging

Waterlogged sites poses a great problem for the site engineer. There are various methods of dealing with the situation which depends upon the depth of excavation, depth of water table and many other factors. Some of the common methods are listed below –

1.  DRAIN CONSTRUCTION – (For shallow foundation) – Drains of suitable size are dug up along the sides of the foundation trench. The drain collects the sub – soil water in the trench and this can then be easily pumped out continuously. This is an easy, low-cost method and does not require skilled labor.
2. DEEP WELL CONSTRUCTION – (Coarse/porous rock based soil) – 30 – 60cm diameter wells are sometimes constructed at 6 – 15 m centers all around the site. The water collected in the wells is pumped out continuously. This method can be adopted for depths of excavation up to 20 m.

Special Methods

1. FREEZING PROCESS – (soil/gravel/silt) – This method is advantageous for deep excavation foundations of bridges adjacent to water body. A cofferdam is constructed by freezing the soil around the region to be excavated. Freezing pipes are sunk into the soil along the periphery of the area. The layout plan is suggested to be in a circular shape. Freezing liquid is then pumped into the pipes making the region freeze. It becomes easy and safe to excavate. Commonly, projects use Salt Brine and some exotic projects use Liquid Nitrogen. The excavation extent – 30m
2. CHEMICAL CONSOLIDATION PROCESS – (Water-logged land) Logged soil is converted into semi solid and stabilize by the addition of chemicals such as soda silicates and calcium chloride. This method is suggest to be used in only small patch project that needs fast results.
3. ELECTRO OSMOSIS PROCESS – (Fine sand) In this process steel rod is charged positively to act as electrode and sunk between well-points. Well-Points act as negative points and when current passes through and water drains towards it, later pumped out. Very Expensive method, rarely used.

Materials & Methods for Foundation Waterproofing

A. Foundation Drainage System

This is a basic setup in this type of waterproofing – perforated pipes running along the perimeters of the foundation to an outlet outside in sunlight or a place where water can be collected in a sump pit and pumped out. This system protects against any kind of water contamination in the basement. The perforated pipes must be laid between layers of gravel. There should also be a layer of fabric barrier on it before putting the soil layer. The fabric and gravel prevents these pipes to clogging up with time.

Foundation/Drainage system of perforated pipes.

• Note: Before laying the drain system, a layer of water proof solution must be applied to the exterior wall.

B. Damp Proof Course (DPC)

DPC is a horizontal barrier on wall structure and its purpose is to stop moisture to rise from the foundation into the structure. This layer is put between layers of walls and is to be applied in both partition wall and the load bearing wall.

Process of DPC:

1. Clean and dampen the horizontal open surface, 15 cm above the highest ground level nearby (level to which water splashes)
2. Mix Cement, Concrete and a Suitable Waterproofing compound in the ratio 1:1.5:3
3. Apply a layer of at least 25 mm thickness
4. After the mixture hardens – Apply the sealant solution layer (x1) horizontally and after a 4 hour period (1x) vertically
5. This is to be applied to the full width, along all the walls of the Foundation/Basement

Basement Waterproofing

The Basement and the Foundation are the places that require the most attention because water can cause major problems. Water can crawl into wall spaces and create a wet damp condition causing molds. This leads to unpleasant foul smell inside the building. If this issue is left unattended, water logging scenario. This can cause property damage inside basements and poses a great threat to the electrical systems which is commonly based in the lower levels. The lift mechanism system faces threat form this causing rusting and total failure. Overall, the whole infrastructure will fail due to these hazard conditions.

Image Source: waterproofers.in

Two methods used in basement waterproofing is the Positive(application on the same side of hydro-static pressure) and the Negative(application on the opposite side of water pressure) waterproofing.

• Positive Waterproofing: In this method, the surrounding perimeters to the building structure is dug – about a meter deep(depends) and layers of waterproofing solution is applied (horizontal x1, vertical x1). This is the best suggested way to protect since the major cause of problem is water pressure from the outside during monsoons.
• Negative Waterproofing: This method must be used in extreme conditions when there is no other way of performing the task from the outside. Cautions must be taken that the materials used are not permeable and do not form honeycomb structures. This application is not very reliable because when the water seeps in, the proofing layer is not always flexible enough to adhere that much pressure.It has been a trend by many contractors to use this method because of the ease and faster application. But this must be avoided and Positive (outside) applications must be undertaken.
• Already Constructed basements can also apply a layer of Kota – Patthar/Stone tiles with Injection Grouting method.

Lift Pit & Sunken Area

Negative  waterproofing method is commonly used because these structures are commonly between other prominent structures and the surrounding areas cannot be dug out. Also, it becomes to dismantle the lift structure. Hence, the layers of waterproofing solutions are applied from the inside.

• INJECTION GROUTING – This is a process of filling cracks, voids of honeycomb between wall layers. This re-strengthens the damaged part of the structure. Grout is a liquid based flow able material of negligible shrinkage used to fill the voids between wall joints or cracks with the use of pressure. Different types of grout materials are used in different cases depending upon the original wall material and the nature of the surrounding walls.

Injection Grouting Process

TYPES Of GROUTING

1. Polymer  – Polyester, Epoxy, Vinyl-ester, Polyurethane and Acrylic resins – used for Anti seepage, underground structures.
2. Fiber-reinforced – polypropylene, Steel or Glass fibers mixed with Portland cement – enhances flexural strength, impact resistance and ductility of the wall.
3. Cement – sand – Most popular grout due to low cost and availability. Not very effectively strong.
4. Gas-forming- Aluminum and Carbon powder based grout with the cement liquor – The gas formed due to material reaction pushes the grout mixture into unreachable cracks. Very fast Process- experts only.
5. Sulfo-aluminate – Anhydrous(containing no water) sulfo aluminate mixed with Portland cement –injected into walls. This method requires water curing(wetting the wall) after hardening. The mixture then expands and fills all voids. This method is better than gas forming because its easy.

Bathroom/Kitchen/Balcony/Chhajja Waterproofing

The situation for these areas in the house has a completely different scenario. The walls and the floors are wet all the time in one way or another.  Since these rooms are adjacent to each other, water leak through one room will ruin the other rooms and its property. The essential thing here is that water only flows through drain pipes. Waterproofing during construction will ensure you will never have to face any issues later.

4 main areas are targeted during proofing – floor, shower splash zone, sanitary fittings, tile joints and nahani traps/drainage pipes.

Material and Methods

Primary materials used in waterproofing these areas –

Waterproof Sealant and Tape

• Water seal Tape- PVC like tape – used to seal fixture/pipes inserts, permanently. Use during pipe and fixture laying.
• Waterproof grout (mixture of cement concrete with waterproof solution)- A free flowing, expanding grout. This fills gap between pipe inserts into concrete/ masonry walls and floors. It is non-shrinking and fast setting material providing long lasting water tight seal.
• Waterproof coat – Advanced performance – cementitious polymer based waterproof coating. Highly elastic material providing up-to 1 mm of thickness from 2 coats -( x1 horizontal; x1 vertical)x2. It usually comes in per-measured combination of liquid and powder – mixed in equal proportions. Brush apply to all the areas, specially shower, under sink etc. Apply a layer of screed( leveled layer of cement). Then the pipes and nahani traps are fixed with the support of brick bat coba layer to keep them in position.

Tiles and other bathroom fixtures – fitted after 48-72 hours of hardening period.

• Waterproof sealant – An elastic based adhesive acrylic sealant – comes in a tube. Applied to all the edges and corners – sinks and bathtub. Extra sealant is applied to the floor level edges and chajja of windows and balcony because the water usually retains at those places. CAUTION: Avoid using low quality white cement putty as it tends to beak and get dirty with time.
• Primer – Adds protection after tiling and plastering of surface. A layer of acrylic based primer. dry up time 4-5 hours. Primer fills any small gaps and cracks.

Common mistakes

Here are some common structure design flaws – Take care during construction.

1. Poor Design/Floor Preparation – The primary thing to take care is of the floor level. It must not have any uneven suppression as water may collect in there in bathrooms, balcony chajja. The level should be flat with a slight inclination towards the drain. The inclination is important since it promotes self drainage of water. The fixtures and drain outlets – carefully placed where most required. Clean all the dirt and construction residue before process.
2. Layers – It is important to apply at least 2 opposite layers of proper waterproof coat. Some contractors tend to save money and time and apply just 1 coat, which is useless.

Terrace Garden & Pool Waterproofing

Terrace area of the building has to endure the most of the nature’s harsh weather, climate and heat. Monsoon plays a major part in this. the heat of the sun causes the rigid surface to expand – causing cracks. Moreover, People now-a-days like to make gardens and swimming pool on the terrace which adds up to the problem of water leakage issues. Due to such constructions there is a need for additional care to take for Terrace type of waterproofing. One of the types of waterproofing is terrace garden and another type is terrace swimming pool. Both of the system need similar types of waterproofing treatment. Differences mentioned below-

TERRACE GARDEN

Also called, roof garden, living roof green roof. CAUTION: Brick bat coba is not a waterproof layer. It is one of the weakest types of waterproofing layer. The primary roof construction must be based of concrete grout and flexible waterproofing polymers.

Terrace Garden Waterproof -Layers

• Layer 1 – 30mm Foam shield – Sand cement and foam mixed in a special mixing device.
• Layer 2- (x2- Coat – Horizontal/Vertical)Roof Sealant Liquid Adhesive based solution. Dries up to form an highly elastic membrane.
• Layer 3- Geo-Textile Fabric– This separates water from soil so that soil does not drain away.
• Layer 4- Concrete Screed – Smooth layer of concrete/cement – sand – 1.3.1. Slope gradient 1:100( slope towards the drains to collect excess water).
• Layer 5- Pyro(Heat) Torch Shield Primer – Creates  a layer for proper adhesion of Torch Shield membrane.
• Layer 6- Pyro Torch Shield (Anti root) Membrane (x2- Coat – Horizontal/Vertical) – Modified bitumen based membrane. Heated by gas blow torches to activate the adhesion that sticks to layer 5. Anti root membrane is safe from roots of the plants.
• Layer 7- Drain Boards – Is a proper channel for excess water in the soil to drain out. Soil filter at the end of drain.
• Geo Textile Fabric – These are permeable fabrics which, when used in association with soil, have the ability to separate, filter, reinforce, protect drain clogging.

TERRACE SWIMMING POOL

Terrace is a very common structure that people like to construct on their building, this adds to the overall value as well and provide a great personal summer relief. The Types of waterproofing method is a bit critical.CAUTION: Strong advise – not to depend on brick bat coba roof to be waterproof. It is one of the weakest types of waterproofing. The primary roof construction must be based of concrete grout and flexible waterproofing polymers. Types of waterproofing methods and layers are –

Terrace Swimming pool Wate

• Layer 1- EPOXY Grouting – (Synthetic thermosetting polymers containing epoxide) This layer fills all the cracks and the corners.
• Layer 2 – Primer – A protective layer that also adds to the foundation of waterproofing.
• Layer 3- Fiber Mesh – Glass based fiber mesh that is extremely strong and rigid against high temperature changes.
• Layer 4 – (x2- Coat – Horizontal/Vertical)Roof Sealant Liquid Adhesive based solution. Dries up to form an highly elastic membrane.
• Layer 5- Plaster – Plaster layer that is based on concrete grout.
• REPEAT LAYER 2-5.
• Layer 6- Tiles –Swimming pool friendly tiles according to need and style of the pool design.
• Layer 7- EPOXY Tile Grouting  (Synthetic thermosetting polymers containing epoxide) This layer fills all the cracks and the corners.

Moreover the most important thing is to find the right contractor. An experienced and trustworthy person is needed. A sense of co-operation must exist between the client and the project head. It is very important the the head must be able to understand and interpret the needs and requirements of the client. All this must be done well under the budget of the project. Think wise, choose well.