Types of Foundation:SHALLOW FOUNDATIONS

Shallow foundations are also called spread footings or open footings. The 'open' refers to the fact that the foundations are made by first excavating all the earth till the bottom of the footing, and then constructing the footing. During the early stages of work, the entire footing is visible to the eye, and is therefore called an open foundation. The idea is that each footing takes the concentrated load of the column and spreads it out over a large area, so that the actual weight on the soil does not exceed thesafe bearing capacityof the soil.

INDIVIDUAL FOOTINGSIndividual footings are one of the most simple and common types of foundations. These are used when the load of the building is carried by columns. Usually, each column will have its own footing. The footing is just a square or rectangular pad of concrete on which the column sits. To get a very rough idea of the size of the footing, the engineer will take the total load on the column and divide it by the safe bearing capacity (SBC) of the soil. For example, if a column has a vertical load of 10T, and the SBC of the soil is 10T/m2, then the area of the footing will be 1m2. In practice, the designer will look at many other factors before preparing a construction design for the footing.STRIP FOOTINGSStrip footingsare commonly found in load-bearing masonry construction, and act as a long strip that supports the weight of an entire wall. These are used where the building loads are carried by entire walls rather than isolated columns, such as in older buildings made of masonry.RAFT OR MAT FOUNDATIONSRaft Foundations, also called Mat Foundations, are most often used when basements are to be constructed. In a raft, the entire basement floor slab acts as the foundation; the weight of the building is spread evenly over the entire footprint of the building. It is called a raft because the building is like a vessel that 'floats' in a sea of soil.

Mat Foundations are used where the soil is week, and therefore building loads have to be spread over a large area, or where columns are closely spaced, which means that if individual footings were used, they would touch each other.DEEP FOUNDATIONS

PILE FOUNDATIONSA pile is basically a long cylinder of a strong material such as concrete that is pushed into the ground so that structures can be supported on top of it.Pile foundations are used in the following situations:

When there is a layer of weak soil at the surface. This layer cannot support the weight of the building, so the loads of the building have to bypass this layer and be transferred to the layer of stronger soil or rock that is below the weak layer.When a building has very heavy, concentrated loads, such as in a high rise structure.

Pile foundations are capable of taking higher loads than spread footings.

There are two types of pile foundations, each of which works in its own way.

End Bearing Piles

In end bearing piles, thebottom end of the pile rests on a layer of especially strong soil or rock. The load of the building is transferred through the pile onto the strong layer. In a sense, this pile acts like a column. The key principle is that the bottom end rests on the surface which is the intersection of a weak and strong layer. The load therefore bypasses the weak layer and is safely transferred to the strong layer.

Friction Piles

Friction piles work on a different principle. The pile transfers the load of the building to the soil across the full height of the pile, by friction. In other words, the entire surface of the pile, which is cylindrical in shape, works to transfer the forces to the soil.

In practice, however, each pile resists load bya combination of end bearing and friction.Foundation is astructural part of a buildingon which a building stands. Foundation transmits and distributes its own load and imposed loads to the soil in such a way that the load bearing capacity of the foundation bed is not exceeded. The solid ground on which the foundation rest is called foundation bed. We use various types of footing as a foundation.

Foundations are mainly two categories.

1. Shallow foundation,and2. Deep foundation.

Seebelow for details:

1- Shallow FoundationShallow foundation is a type of foundation that transfers load to the very near the surface. Shallow foundations typically have a depth to width ratio of less than 1.

Various types ofShallow Foundations:Following are the types shallow foundations - Pad footing or column footing Cantilever or strap footings Mat/Raft footings Wall FootingsPad footing or column footingThis type of footing can be two types - Isolated and Combined.Isolated footingThese are most economical. They are usually in square or rectangle size with the columnsitting in the middle of the square. It's a kind of pad footing.

Combined footingA footing, either rectangular or trapezoidal, that supports two columns. It's also a padfooting.

Cantilever or strap footingsConsist of two single footings connected with a beam or a strap and support two single columns.

Mat/Raft footingsConsist of one footing usually placed under the entire building area. They are used when soil bearing capacity is low, column loads are heavy, single footing cant be used, piles are not used and differential settlement must be reduced.

Wall FootingsWall footingsare used to distribute the loads of structural load-bearing walls to the soil.

2- Deep FoundationsDeep foundationsare those founding too deeply below the finished ground surface for their base bearing capacity to be affected by surface conditions, this is usually at depths of 3 meter below finished ground level. Deep foundations can be used to transfer the load to a deeper, more competent strata at depth if unsuitable soils are present near the surface.

Common Type of Deep Foundation :Pile foundationsare common type of deep foundation. Theseare relatively long, slender members that transmit foundation loads through soil strata of low bearing capacity to deeper soil or rock strata having a high bearing capacity. They are used when for economic, constructional or soil condition considerations it is desirable totransmit loads to strata beyond the practical reach of shallow foundations.

Inaddition to supporting structures, piles are also used to anchor structures against uplift forces and to assist structures in resisting lateral and overturning forces.

Thick slabs are used to tie a group of piles together to support and transmit column loads tothe piles.types of raft or mat foundation.

A true raft or mat is a flat concrete slab with uniform thickness throughout the area, as shown inFig. 3.26 (a). This is adopted only when the column spacing is small and column loads are also relatively small. If the column loads are heavy, the slab under the columns is thickened, as shown inFigs. 3.26 (b) and (c). If the column spacing is large, and/or the column loads are heavy, thickened bands may be provided along the column lines in both the directions. These bands are cal1ed main and secondary beams. If the loads are extremely heavy, two way grid structure made of cellular construction[Fig. 3.26 (e)]may be used. Where basements are to be provided, the basement walls may be used a ribs or deep beams[Fig. 3.25 (f)]. A raft often rests directly on soil or rock. However, it may also rest on piles.

Ordinarily, rafts are designed as reinforced concrete flat slabs. If the C.G. of loads coincide with the centroid of the rift, the upward load is regarded as a uniform pressure equal to the downward load divided by the area of the raft. The weight of the raft is not considered in the structural design because it is assumed to be carried directly by the subsoil. Since this method does not take into account moments and shears caused by differential settlements, it is customary to reinforce the raft more heavily than required according to the analysis.

FIG. 3.26COMMON TYPES OF RAFT FOUNDATION.(a) Flat plate type (b) Flat plate thickened under columns (c) Flat plate with padestals (d) Two way beam and slab type (e) Cellular construction (f) Basement walls as rigid frame.PILE FOUNDATIONSA pile is basically a long cylinder of a strong material such as concrete that is pushed into the ground to act as a steady support for structures built on top of it.Pile foundations are used in the following situations:

1. When there is a layer of weak soil at the surface. This layer cannot support the weight of the building, so the loads of the building have to bypass this layer and be transferred to the layer of stronger soil or rock that is below the weak layer.2. When a building has very heavy, concentrated loads, such as in a high rise structure, bridge, or water tank.

Pile foundations are capable of taking higher loads than spread footings.

There are two types of pile foundations, each of which works in its own way.End Bearing Piles

In end bearing piles, thebottom end of the pile rests on a layer of especially strong soil or rock. The load of the building is transferred through the pile onto the strong layer. In a sense, this pile acts like a column. The key principle is that the bottom end rests on the surface which is the intersection of a weak and strong layer. The load therefore bypasses the weak layer and is safely transferred to the strong layer.

Friction Piles

Friction piles work on a different principle. The pile transfers the load of the building to the soil across the full height of the pile, by friction. In other words, the entire surface of the pile, which is cylindrical in shape, works to transfer the forces to the soil.

To visualise how this works, imagine you are pushing a solid metal rod ofsay 4mm diameter into a tub of frozen ice cream. Once you have pushed it in, it is strong enough to support some load. The greater theembedment depthin the ice cream, the more load it can support. This is very similar to how a friction pile works. In a friction pile, the amount of load a pile can support is directly proportionate to its length.

WHAT ARE PILES MADE OF?Piles can be made of wood, concrete, or steel.

In traditional construction, wooden piles were used to support buildings in areas with weak soil. Wood piles are still used to make jetties. For this one needs trees with exceptionally straight trunks. The pile length is limited to the length of a single tree, about 20m, since one cannot join together two tree trunks. The entire city of Venice in Italy is famous for being built on wooden piles over the sea water.

Cross sections of various pile foundationsConcrete piles are precast, that is, made at ground level, and then driven into the ground by hammering - more on that later. Steel H-piles can also be driven into the ground. These can take very heavy loads, and save time during construction, as the pile casting process is eliminated. No protective coating is given to the steel, as during driving, this would be scraped away by the soil. In areas with corrosive soil, concrete piles should be used.

HOW PILES ARE USEDAs pile foundations carry a lot of load, they must be designed very carefully. A good engineer will study the soil the piles are placed in to ensure that the soil is not overloaded beyond its bearing capacity.

Every pile has azone of influenceon the soil around it. Care must be taken to space the piles far enough apart so that loads are distributed evenly over the entire bulb of soil that carries them, and not concentrated into a few areas.

The load pattern of the piles on the soil surrounding them. This is also called a zone of influence.Engineers will usually group a few piles together, and top them with a pile cap. A pile cap is a very thick cap of concrete that extends over a small group of piles, and serves as a base on which a column can be constructed. The load of this column is then distributed to all the piles in the group.HOW PILES ARE CONSTRUCTED

Piles are first cast at ground level and then hammered ordriveninto the ground using apile driver. This is a machine that holds the pile perfectly vertical, and then hammers it into the ground blow by blow. Each blow is is struck by lifting a heavy weight and dropping it on the top of the pile - the pile is temporarily covered with a steel cap to prevent it from disintegrating. The pile driver thus performs two functions - first, it acts as a crane, and lifts the pile from a horizontal position on the ground and rotates it into the correct vertical position, and second, it hammers the pile down into the ground.

Piles should be hammered into the groundtill refusal, at which point they cannot be driven any further into the soil.SPECIAL PILESPile driving is very noisy and causes massive vibrations through the soil. For this reason, it is sometimes difficult to use them in sensitive locations. For example, if an operational hospital or science lab is to be extended, driving piles would cause unwanted disturbance. Their use is also restricted in residential areas in many countries. The vibrations could also cause structural damage to older buildings that are close by. In such situations it is possible to usemicro pilingor helical piling,neither of which rely on hammering.

Micro piles or minipiles are small piles that are constructed in the following way:Step 1:a hole a little larger than the pile diameter and the full length of the pile is dug into the ground using an apparatus like a soil boring machine.Step 2:a precast concrete pile is lowered or pushed into the hole.Step 3:a concrete grout is poured into the gap between the pile and the earth.

Helical pilesare steel tubes that have helical (spiral) blades attached to them. These can be drilled into the ground, meaning that the pile acts as a giant drill bit, and is rotated and pushed into the ground from above, much like a screw drills into wood. Once the steel pile is driven into the ground, a pile cap is poured on top of the pile to prepare it for the construction above.

The waterproofing of buildings to prevent the ingress of water is an activity, which, perhaps is practiced in one form or the other, ever since the first building was built on earth. The methodology has been changing with the changes in architectural designs and availability of different building materials for construction. In the initial stages when stone was the main building construction material placed in position with mud or lime mortar, the emphasis used was to make the construction in such a way that the rainwater does not collect on the roofs. Hence old architecture relied mainly on dome structures or slanting/slopy roofs. The slow speed of such construction and unaffordability by common man to build such structures for their own dwelling, made constant evolution and development in the construction material technology. With new developments, the concepts of waterproofing have also changed. Now in the present day construction with ordinary portland cement and its blends (with puzzolonic and slag materials) a lot of compatible alternatives, are available to a builder to choose from various waterproofing systems. Some systems are old and conventional but still practiced successfully and some are modern systems designed taking the material and structural behavior into consideration.

There are some compounds, which are used as aaditive in plastic concrete to make it less permeable to water. These compounds are known as integral waterproofing compounds. They are based on plasticising and air-entrainment or water repellence principles. These are used as a good waterproofing precautions when other factors such as good mix-design, proper mixing/placing, compacting/curing etc are taken care of. This subject of using integral waterproofing compounds requires an in depth discussion hence will not be taken up here. Similarly, there are many waterproofing techniques for vertical surfaces. These techniques used are also used for preserving heritage buildings by stopping/minimising the aging process of these buildings. This subject also will not be discussed here.

First of all let us review some of the old and conventional waterproofing systems and then we would discuss the modern waterproofing techniques.Review of Conventional Waterproofing SystemsSome of the conventional water- proofing systems are as follows: Brick Bat Coba system or Lime Terracing Bituminous Treatment Metallic Sheet Wrapping Poly-urethane based Water- proofing treatment Epoxy Based Waterproofing Treatment Box Type Waterproofing SystemBrick Bat Coba System

This system was developed during the initial stages of flat roof construction with lime mortar & burnt clay brick aggregate. This system involved laying of lightweight mortar on the roof and spreading it to give gentle slopes for draining away the rainwater immediately. The mortar consisted of lightweight brick pieces as aggregates and ground brick with lime as binding matrix. During British rule, this system became more popular not because of its waterproofing efficiency but because of its efficiency in keeping the interiors cool. Some applicators developed better skills in laying these systems with neatly finished top with lines engraved on top of plastic mortar now known as IPS. Some practiced embedding broken tile or ceramic pieces in the plastic mortar and called it China mosaic. This type of system remained most popular with multi-storeyed construction in all major cities. The system lasts approximately up to 15 years if done by skillful applicators. This system may be considered more from its weatherproof abilities rather than its waterproofing qualities. Once water starts entering into the brickbat coba the brick pieces absorb too much of water and the roof becomes an invisible water pond continuously causing leakage and increasing burden on the roof slab. It will be highly beneficial if brick-bat coba, is laid on a flexible waterproofing membrane as water proofing as well as economical weather proof can be achieved with this system.

Bituminous Treatment

Discovery of petroleum and its products and by-products has given the construction industry an indispensable product in the form of bitumen. Bitumen is more commonly used in the form of felt or flexible membrane formed by sandwiching jute fabric or fibreglass/polypropylene mats with chemically modified bitumen. These membranes are laid on the roofing system over a bitumen primer. There are two types of membranes one is cold applied and the other is hot applied which means one needs to heat the edges of the felt with a torch so that they melt and stick to the second layer in the overlap area. On the RCC flat roofs, the bitumen felts have not been successful because of the unacceptable black appearance and inaccessibility of the terrace for other social uses. Technically, it is not preferred because bitumen layer or felt on the terrace not only makes it watertight but also airtight. Concrete has the breathing property. It takes water/moisture and breathes out water vapour. Hindrance of this breathing property of concrete develops pore pressure which causes blisters in the felt. After a few seasons, the blisters multiply and eventually delaminate the felt from the concrete surface. Hindrance of breathing property of concrete, makes the concrete weak. But on the asbestos cement sheets and zinc sheets in factory roofs, this bitumen felt is the only dependable waterproofing system. Hence most of the factory roofs in India adopt this waterproofing system.

Bitumen is very effective in waterproofing of basements from outside. Bitumen primers have very successfully been used as damp-proof course in earlier days. This practice is slowly discontinued for whatever reasons now very few engineers believe that this was in practice once. As consequence of this absent DPC, we have a lot of cases of rising dampness, which we tend to attribute to wrong reasons such as the quality or salinity of sand etc. Bitumen is still the product of first choice where it is commonly recommended, in areas such as industrial roof waterproofing, basement water- proofing, and damp-proof course. Moreover, bitumen is the most economical product presently available for waterproofing. But black top over roof can absorb heat and this need to be kept in mind while deciding waterproofing system for exposed roofs.

Metallic Sheet Wrapping

Because of the non-existence of suitable expansion joint filling compounds before the discovery of poly-sulphides, a complex procedure used to be adopted to treat expansion joints in concrete dams and such huge structures utilising thick copper sheets. An extension of this practice was to try thin foils of copper and aluminium for wrapping the concrete surfaces with nagging leakage problems. Unavailability of common joining material for these metal foils and the concrete and mortar created weakness in the system at the joints. This discouraged the system in its infancy only. But thereafter, the metal manufacturers have been trying to market this type of waterproofing system with improved adhesives and when the metal market slumped.

Polyurethane Based Waterproofing Treatment

Polyurethane consists of two liquid components one is called the Base component and the other is called reactor or curing agent. Base is a polyol and the reactor is an isocyanide such as TDI or MDI. There are various grades of polyols and numerous isocyanides. The combination of these two ingredients results in a formation liquid applied rigid membrane or a foam depending upon the selection.

In waterproofing, this rigid liquid membrane was tried with fibreglass reinforcing mats. The systems failed because coefficients of thermal expansion of concrete and rigid PU membrane being different lateral movement or creep occurred with the passage on one working climatic cycle. When exposed to ultra violet rays or direct sunlight, most polyurethane rigid membranes became brittle and crumbled. Apart from this, the application of polyurethane coating needed very rigorous surface preparation. The surface needed to be neutralized by removing alkalinity from the concrete surface through acid itching then washing and blowtorching to make the surface bone dry. This kind of surface preparation with acids angered, the civil engineering community and the product ceased to be used as waterproofing material apart from its several failures. Never the less continuous research in the polyurethane technology gave the construction industry excellent sealant for glazing industry and foams for thermal insulations. The new generation polyurethanes which are alkali stable and water-based, may find better applications in waterproofing industry.

Epoxy Based Water- proofing System

Like polyurethane expoxy is also a two-component system having a base resin and a reactor or curing agent. Base resin is obtained by dissolving Bis-phenol A flakes in epichlorohydrin. This base is available in various viscosity ranges to suit different application conditions. The curing agent is an amine/polyamine aliphatic or aromatic or an amine-adduct for general applications and polyamide or an amino-amide for coating purposes. After mixing base and reactor components, the resultant viscous liquid or paste if some fillers are added to it can be brush applied like a paint or trowel applied like a mortar.

Not withstanding, the alkalinity of concrete and the concrete needs to be acid washed and neutralised which the civil engineers donot agree. Here again the coefficient of thermal expansion of concrete and epoxy being different the compatibility of epoxy in waterproofing exposed concrete surfaces such as roofs became limited. Later the use of epoxy in waterproofing was discarded. But epoxies have come to stay in civil engineering industry as bonding agents, floor & wall coatings, coatings for food processing units, operation theatres and computer and pharmaceutical industries.

Box Type Waterproofing

This type of waterproofing system is used only for basement waterproofing or structures below the ground level from outside to prevent leakages of subsoil water into the basement.

In this method, limestone slabs (Shahabad Stones) are first laid in the excavated pit over blinding concrete in a staggered joint fashion to avoid the continuity of the mortar joints. The joints are effectively filled with rich cement, sand mortar admixed with integral waterproofing compound and cured. Over this, the raft is laid and shear/brick walls constructed. The limestone slabs are erected around the walls in a similar fashion leaving a gap of one to two inches between the external surface of the wall and the inner face of the stone surface. The joints again effectively sealed with rich admixed mortar and the same mortar is filled in the gap between the wall and the stones. This stonework is continued up to ground level. In this system, the raft and the sidewalls are protected from direct exposure to sub soil water.

This system works on two principles of common sense. First the area exposed to subsoil water is only the area of the joint where as the whole stone is impervious to water, hence only a fraction of area, that is, that of the joint is exposed to subsoil water when the joint itself is filled with rich and quality mortar. Secondly, the path of water to reach the raft or the sidewall is elongated. This elongated path is through quality mortar. This system seeks to delay the occurrence of leakages in the basements. A lot of building structures are waterproofed using this system. A few notable successes are to its credit especially in five star hotels and of-course there are a few failures as well.Modern Techniques in Waterproofing

Modern technique aims to understand the functional behaviour of the structure, understand the properties of the available materials to arrive at a system, which is best suited for the structure and incorporate the system at the design stage itself.

A single product or technique is not usually enough, involvement of various bodies and techniques in coordination is essential for making structures waterproof. For success of any system, the building structure should have sufficient and efficient control joints if the slabs dimensions are more than twenty meter in any direction. Control joints are structural engineering design features. These joints are supposed to be designed and their configuration marked on the drawings and their detailing needs to be given with respect to waterproofing system proposed in large buildings. Different types of control joints are Construction joints or day joint, crack inducer joint, contraction joint and expansion joint. Coefficient of thermal expansion of concrete is between 6 to 10 X 10-6 mm/mm/oC. If proper control joints are not provided in large slabs, no waterproofing system will work. Modern technique relies basically on two main waterproofing systems, which are fool proof and simple.

They are as follows: Crystalline waterproofing system Flexible membrane waterproofing systemCrystalline Waterproofing System

This system involves blocking the water bearing capillaries with insoluble crystals. This method is used for waterproofing of water-retaining structures like overhead/underground water tanks, sunk slabs of bathrooms and toilets, swimming pools, basements, terrace gardens etc. The main product in this system is a grey or brown looking powder.

The method of treatment involves saturating with water the surface to be treated. Then mixing two and half volume of the powder with one volume of water to form neat consistency hot slurry. This slurry is brush applied on the saturated surface. The active ingredients in the slurry pass through the water bearing capillaries and react with calcium oxide present in the concrete to form insoluble crystals, which effectively block the capillaries. Further the chemical ingredients of the product remain in concrete to reactivate the process of crystallisation and when a new capillary is developed. This system of waterproofing, the water retaining structures is practiced in most of the developed countries. Typical specification for this type of system is as follows:

i. Clean the surface to remove all loose particles, grease shuttering oil and such deleterious materials to get a sound concrete surface.ii. Cracks if any should be cut into V shaped grooves one inch wide and proper size width & depth Cut honey combed areas back to sound concrete.iii. Repair these areas first by priming with crystalline waterproofing slurry and then by filling them with crystalline modified mortar produced by mixing crystalline waterproofing powder OPC and zone II sand in the proportion of 1:1:4 and water enough to produce a stiff consistence paste. Allow the repair mortar to dry.iv. Thoroughly sprinkle water on the area to be treated till the surface becomes saturated. Some recommend overnight ponding for effective resultsv. Prepare crystalline waterproofing slurry by mixing the powder and water in the proportion of two and half volume of powder to one volume of water to form a hot slurry. Brush apply this slurry on the water saturated surface in two coats.vi. When the second coat is still wet plaster the surface with 1 : 4 cement sand mortar admixed with an integral waterproofing compound and cure properly.Flexible Membrane Waterproofing System

The main product used in this system, comprises two components one liquid and the other is a powder packed roughly in the proportion of 1:4 by weight. The liquid component is an acrylic emulsion and the powder component is a polymer-modified cement with film forming chemicals and fillers, and some manufacturers add reinforcing fibres to make the product extra effective.

When these two ingredients namely the pre-weighed powder and the liquid are mixed together an uniform slurry results. This slurry is brush applied on the roof surface, which upon drying forms a flexible film. Since there is cement in this product, its compatibility with concrete is excellent. The film further allows the breathing of the concrete without any hindrance hence there is no problem of its de-lamination from the concrete surface. This film being flexible takes care of the deflections in the slab and the movements caused because of primary or secondary settlements, movements due to wind loads and temperature stresses developed in the concrete. This system can be used on surfaces which had bituminous treatment earlier. In European countries, this type of product is used as coating on pre-stressed concrete bridge girders to protect them from aggressive chemical atmosphere. A typical waterproofing specification using flexible membrane system will be as follows:

i. Clean the surface to remove all loose particles, grease shuttering oil and such deleterious materials to get a sound concrete surface.ii. Cracks if any should be cut into V shaped grooves of a proper size in depth. Cut honey combed areas back to sound concrete.iii. Repair these areas with a stiff paste of fibre reinforced polymer repair mortar generally sold in the name of crack fill.iv. Mix the powder and the liquid components of the product to form an uniform slurry and brush apply this slurry on the surface to be waterproofed.v. When the waterproofing coating is still tacky apply 1 : 4 cement sand screed and cure normally.Ferrocement Waterproofing SystemFerrocement is a cement based high strength Semi Flexible Composite used for construction of water retaining and resisting structures, boats, roofs, pipes etc. In SERC Roorkee the ferrocement group headed by Er. P.C. Sharma developed ferrocement lining technology for waterproofing and jacketing of RCC (for strengthening) & masonary structures. The structures like Calico mills Ahmedabad, Khatima Power Station, BHEL Turbine Testing Lab Caliberation Tank at Haridwar done more than 30 years ago have behaved well. The system is simple but need skills and proper training. NBM&CW has published many articles on this topic providing total know how.

Ferrocement has great bond with cement concrete and brick surface and is reinforced with at least two woven mesh layers. Thickness of this treatment is generally between 12 to 20 mm. Large number of basements, overhead tanks, underground reservoirs and important roofs have been treated using this technique. When life cycle cost is considered it is the cheapest waterproofing system today which add strength to the original structure in addition to waterproofing.

Failure of Waterproofing Systems

Especially in large buildings, waterproofing systems fail if the control joints are not in position or not properly executed and maintained. This failure occurs even after one complete year when the structure has passed through one complete summer and the winter cycle. One cant repair this type of failures. It needs a different type of approach involving provision of crack inducer joints and then tackling the waterproofing in movement restricted bays. Application of a waterproofing product in non-specified areas, such as using a crystalline waterproofing system in waterproofing the terrace or using a flexible membrane system in the water tank results in failures even though the products themselves may be genuine. Stretching the coverage of the products beyond the specified limits by the manufacturer results in inefficiency of the product and hence a failure.Precautions to be Taken by the Client and Consultant. Selection of an effective waterproofing system for a structure taking all the performance criteria of the structure into account and also taking into the consideration, the performance of the materials in the system is of prime importance for any success of the waterproofing job. Waterproofing jobs awarded to waterproofing contractors purely on economical price considerations often fail. It is always advisable to involve the architect or the structural engineer in selection of a system and requisite performance guarantees should be taken from the contractors. It is better to avoid bargaining for the job value out of contractors margins. This could result in stretching the product beyond the coverage specified by the manufacturer or substitution of cheaper material in the system to cover the cost. Always supervise the job and the incoming materials for the intact tamperproof seals and quantities. Use the services of an engineer or architect in selection of materials. That too only procured from well know manufacturing firm.Conclusion Generally, architects in India, do not specify in depth waterproofing details and leave this aspect generally to ignorant client to chose whatever system he likes, and many structural designers give least importance to the control joints. As a result of this, many systems have failed in several prestigious buildings and the blame went to waterproofing contractors or the product manufacturer. There is a need for the architects and the structural designers to understand the various systems available and specify them clearly and in sufficient detail, taking into consideration the in-service conditions of the structure. The client should also insist on the architect to provide waterproofing design details in advance so that no ambiguity remains till the end. This would give enough time in selecting the specified material.Some of the benefits are :a. The dry cladding method is safe and chances of stone falling down at a later date is remote.b. Method allow for expansion and contraction of stone in extreme weather conditions.c. The dry cladding method creates a gap of around 30 to 45 mm in between back wall and stone lining , providing a layer of air cushion that acts as a thermal barrier.d. The appearance of stone used in dry cladding work looks aesthetically pleasing. The stone fixed with mortar may change in colour due to absorption of water from back mortar layer.Laminated glass specifications:A typical laminated makeup is 2.5mm glass / 0.38mm interlayer / 2.5mm glass. This gives a final product that would be referred to as 5.38 laminated glass.Multiple laminates and thicker glass increases the strength.Bullet-resistant glassis usually constructed usingpolycarbonate,thermoplastic materials,thermoset EVA, and layers of laminated glass. A similar glass is often used in airliners on the front windows, often three sheets of 6mm toughened glass with thick PVB between them.Newer developments have increased the thermoplastic family for the lamination of glass. Beside PVB, important thermoplastic glass lamination materials today areethylene-vinyl acetate(EVA),[16]thermoset EVAethylene-vinyl acetate(EVA)[17]and thermoplastic polyurethane (TPU).[18]The adhesion of PVB/TPU and EVA is not only high to glass, but also to polyester (PE) interlayers. Since 2004 metallised and electroconductivepolyethylene terephthalate(PET) interlayers are used as substrate for light emitting diodes and laminated to or between glass. Top layer: Glass Interlayer: Transparent thermoplastic materials (TPU or PVB, EVA) or transparent thermoset material (EVA) Interlayer: LED (light emitting diodes)on transparent conductive Polymer Interlayer: Transparent thermoplastic materials (TPU or PVB, EVA) or transparent thermoset material (EVA) Bottom layer: GlassLaminated glass is also sometimes used in glass sculptures.Toughened glass specification:Insulated glass specification:Tempered glass specification:Frost free glass specification: