12 December 2019

Spotlight-Perma

Foolproof choice

 

Preventing the ingress of water into a building is an activity which has been practiced in one form or the other ever since the first building was built on earth. The methodology, commonly known as waterproofing has been changing with the changes in the architectural designs and with the availability different building materials in construction. Some systems are old and conventional but still practiced successfully and some are modern systems designed taking the material and structural behaviour into consideration.

 

MODERN TECHNIQUES

Modern technique aims to understand the functional behaviour of the structure, understand the properties of the available materials arrive at a system, which is best suited for the structure and incorporate the system at the design stage only. A single product or technique is not usually enough, involvement of various bodies and techniques in coordination is essential for making structures waterproof.

Modern technique relies basically on the following two main waterproofing systems, which are fool proof and simple.

  • Crystalline waterproofing system: This system involves blocking the water bearing capillaries with insoluble crystals. This method is used for waterproofing 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.
  • Flexible membrane water proofing system: The main product used in this system comprises of 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 polymer-modified cement with film forming chemicals and fillers, and some manufacturers add reinforcing fibres to make the product extra effective.

 

FAILURE OF WATER PROOFING SYSTEMS

  • Especially in large buildings waterproofing systems fail if the control joints are not in position or not properly executed. This failure occurs after one complete year when the structure has passed through one complete summer and the winter cycle. One can’t 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

  • 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 contractor’s 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.

 

CONCLUSIONS

  • 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.

 

For more details contact:

Email: info@permaindia.com

Website: www.permaindia.com | www.permaindia.net

 




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