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Myths & Tips

(Reproduced from www.jagvirgoyal.com with the permission of the author)
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  • Myths-5 Construction Practices to be Avoid
A civil engineer by profession, Mr. Jagvir Goyal is the author of a number of books and technical papers. Hundreds of articles written by him on technical subjects are published from time to time in many periodicals including The Tribune, a reputed newspaper of North India, Construction World, published monthly from Mumbai and Gulf, New Building Materials & Construction World, published from New Delhi, Construction Journal of India, published from Mumbai, EPC & I, Power Today & Equipment India published from Mumbai and many more publications. His weekly column, ‘Racy Building Strategies’ published in Hindustan Times (Chandigarh edition) since May, 2006 evoked tremendous response from the people of northern region. His fortnightly column, Ground Realty, published by The Tribune has entered 6th year of publication and is extremely popular among Tribune readers.

  1. Avoid construction joints in basements or keep their number as minimum.
  2. Remember that construction joints are vulnerable points for leakage into the basements. Fully prepare and treat their locations carefully to avoid any leakage from there.
  3. Enter all conduits for electricity and other services into the basement from a level above the ground level.
  4. Take extreme care and precaution if you are planning to construct a basement. Good ventilation and freedom from dampness are prime requirements of a basement.
  5. Note that basements can be made leak proof during construction only. In post construction treatment, only inner and leaking face is available for repair work while the outer face where the problem lies can’t be accessed.
  6. For basement construction, whenever a construction joint is given, treat it well before laying further concrete. For treatment of construction joint in basement, chip off old concrete if it is older than a day and roughen it with wire brush if it is few hours old and still looks green. Apply 1 part acrylic polymer and 2 part cement slurry over old concrete and only then lay the fresh concrete. Always fix nozzles in the walls, preferably at construction joints for grouting the walls with non-shrink injection grout at a later stage if leakage or dampness is noted.
  7. IS 2933 paints are enamel paints while IS 2932 paints are synthetic enamel paints.
  8. Over-thinning of paint will eliminate its gloss or shine landing you with a dull surface.
  9. If the manufacturer advises to use thinner for paints, use turpentine oil or the specified thinner. It shouldn't affect colour or uniformity of the paint.
  10. Melamine or Polyurethane finishes can be applied with brush, cotton cloth or can be sprayed.
  11. Apply masking tape or provide paint shield on glass panes during painting or polishing of windows.
  12. Cement absorbs moisture from air. If more than two months old, get it tested.
  13. 53 grade cement requires more curing and should be chosen if adequate curing arrangements are available.
  14. OPC grade 33 carries IS269 mark, grade 43 carries IS 8112 mark and grade 53 carries IS 12269 mark.
  15. Check the date of manufacture and accept cement bags less than two months old.
  16. Choose right grade of cement.
  17. Always use fresh cement for construction work.
  18. Always select a reputed brand of cement.
  19. Cement bags carry tags showing the week and year of manufacture
  20. When getting sand from the rivers, get it from near the inner edge of meander.
  21. Proper storage of sand helps in preventing mixing of soil with sand.
  22. More is the clay or silt in sand, more unsuitable it becomes for use.
  23. Engineers check the quality of sand by checking its Fineness Modulus.
  24. Quality of sand plays an important part in building construction.
  25. If the water contains dissolved chlorides or sulphates, it may cause great harm to the steel embedded in concrete.
  26. Quality of the reinforcement steel plays a very important role in determining the life of the building.
  27. If beams laid over the walls make a band, it will help in earthquake resistance and will avert some effect of differential settlement of foundations on the building.
  28. Keep the concrete mix for plinth beams as M20 or 1: 1.5: 3.
  29. If you plan to provide plinth beams instead of Damp Proof Course, match top level of these beams with the floor level.
  30. Melamine based finish adds great beauty to the woodwork, resists all sorts of scratches and stains but is costliest among the three finishes.
  31. See that no wedges are inserted by the carpenter in the door joints to tighten them. The joints should themselves be tight fitting and without any visible gaps
  32. Position lights in bathrooms in a manner that these shine over the face and not on the mirrors.
  33. For door and window frames, use creosote oil conforming to IS 218. IS marked creosote oil undergoes many tests such as specific gravity, water content and matter insoluble in toluene.
  34. For washbasins and bathtubs, choose pop up wastes. These can be operated at the flick of a lever and all dirty water drains out completely.
  35. See that the tenons of the door verticals fully penetrate the width of the top member. Well apply some adhesive like Fevicol or Synthetic Resin all around the tenon and groove before inserting it in position.
  36. Take up flooring work only when all plastering work on inside of walls, outside of walls and ceilings has been completed.
  37. Wooden frames that carry one set of shutters for doors, windows and ventilators are noted as D, W, V on the drawings
  38. PPC has no grading and its bags carry IS1489 mark.
  39. Always wash the new brushes well with soap solution before use
  40. Always prefer to choose light shades for bathroom fittings. Dark shades don’t remain attractive for long.
  41. Provide pull cords for switching on or off all bathroom electric fittings. This is a must to avoid touching switches and fittings with wet hands.
  42. Never forget to provide ‘mosquito nets’ on the mouths of overflow pipes of cisterns. Generally, these pipes are of 20 mm diameter and mosquito nets are available with the dealers.
  43. Always look for a good source of water.
Some construction methods introduced decades ago as per materials and equipment available at those times are still prevalent in India. There is a vast improvement in the quality of materials and availability of equipment now and these old and bad methods are no more relevant to today’s times. Yet people continue to follow these in many parts of the country. The forces behind using these methods are those masons who are skilled in these practices and enforce them upon the house builder.

Whenever a house builder tries to depart from the old and bad methods of construction, a mason’s standard reply is, "If you want to differ, I won’t be responsible for the consequences." The house builder is caught in a dilemma. This standard plea of the masons influences the house builder who resigns to the mason’s will. To have good quality and safety in construction of your house, don’t allow the mason’s dictum to prevail. Follow your engineer’s advice. Not only the quality and safety but also economy and durability in construction shall be achieved. Here are a few bad methods of construction. Avoid these and see the results:

1. USING EXTRA REINFORCEMENT

Inserting extra reinforcement in beams and slabs does not help in strengthening the structure. Masons and bar binders try to insert the steel cut pieces here and there in the slab under the impression that this will make the slab stronger. They are badly mistaken. Steel bars require certain free spacing between them to allow easy flow of concrete through them. Inserting of cut pieces stops this flow and makes the concrete less dense. Result is that the slab may rather be weaker.

Get your slab designed from a structural engineer. He may bring lot of saving to you. Sometimes, a mason is so disturbed over the design of slab that he refuses to accept such less quantity of steel. Don’t allow his fears to prevail upon you and get the steel laid as per design given by the engineer. Know that over reinforced slabs and beams make a building unhealthy.

2. RB ROOFING IN HOUSING

It is a major practice followed in India. Reinforced Brick (RB) roofing in houses is more common than the strong, impervious and economical RCC. There prevails a belief that RCC roofing develops cracks while RB roofing does not. RB roofing has bricks laid on edge and covered with a 40 mm thick layer of concrete. Steel reinforcement is laid in the gaps left between the bricks laid on edge. A bottom cover of 12 mm is provided to the reinforcement. Total thickness of slab works out as 167 mm. Spacing of reinforcement gets decided by the brick-laying-arrangement in this type of roofing. On the other hand, RCC roofing laid under similar conditions is just 113 mm thick.

Its reinforcement spacing is decided by the designer. In the long run, RCC roofing in fact proves cheaper. As and when RB roofing is laid, bricks being highly porous, soak water from concrete resulting in cracks in top layer of concrete. Steel bars placed in betwe bricks come in contact with them and rusting of bars occurs after a few years. Then there is no remedy except to dismantle the slab and Re-lay it afresh. This is an impossible task as the whole of the house is to be undone. The only factor that goes in favour of RB roofing is the low thermal conductivity of bricks. This may help in lesser expansion of slab and better insulation to heat. However, this factor weighs little against the drawbacks this type of roofing suffers from.

If proper end treatment is given to RCC slabs by providing a 6 to 8 mm gap at its end filled with a filler and a 10mm bearing plaster is provided at the base, no cracks will appear in the RCC roofing. The practice of using RB roofing should therefore be stopped altogether and only RCC roofing should be used.


3. HAND MIXING OF CONCRETE

Indian specifications sometimes allow "Hand mixing" of concrete. Whatsoever precautions you may take, hand mixing of concrete will not produce desirable blending of concrete ingredients. Consumption of cement will also be more. Water-cement-ratio will also not remain under control. Therefore, avoid hand mixing of concrete. If unavoidable, allow it for lean concrete only. Nonuniform mixing of ingredients in hand mixed concrete means lack of workability, Strength and density of concrete.

4. USING UNCONTROLLED CONCRETE

Some specifications and Common Schedule of Rates widely followed in execution of works allow use of un-designed concrete in construction of houses and buildings. Naturally, specified minimum cement content factors for this concrete are very high as compared to the cement required for designed concrete. There is double loss on use of un-designed concrete. More cement is used resulting in higher expenditure. Secondly, you are not sure about the strength of concrete. Mere addition of extra cement doesn’t assure strength and durability. Proper mix design is necessary.

Use of RMC (Ready Mixed Concrete) is now increasing in India. It is concrete produced under fully controlled conditions. If you have an RMC plant near your plot, feel blessed and use RMC. You will avoid a lot of trouble and tension. Recently, some RMC plants have come up in Panchkula and Mohali. So people of the tri-city can avail of their availability.

5. NON-USAGE OF ADMIXTURES

There is a revolution in the development of admixtures and compounds. Development of Super plasticizers, water proofing admixtures and sealants have opened endless possibilities of easier laying of concrete, saving old Buildings, making new buildings damp-proof, impervious and efflorescence free. However people are reluctant in use of these admixtures. These admixtures and compounds can enhance the quality of construction itself. Make use of this synthesis of chemistry and construction.

Ask a house owner, hotel manager, maintenance engineer or care taker, the major problems being faced by him are leakage, seepage, cracks or efflorescence. Right use of admixtures and compounds can help in eliminating these problems.However the use of these admixtures has not become common in India. There are no reasons for not taking full benefit of these wonderful materials. It is a bad practice with us to adopt new materials at a very slow pace and with suspicion thus depriving ourselves of their benefits at the Right moment.

 

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