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 builder is caught in a dilemma. For safety in construction, don't allow mason's dictum to prevail. Follow engineer's advice. This way economy and durability in construction shall be achieved besides, quality and safety.

Here are a few bad methods of construction. Avoid these:

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 to be 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. The designer decides its reinforcement spacing. 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 between bricks come in contact with them and rusting of bar occurs after a few years. There is then no remedy except dismantling the slab. 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, filled with asbestos filler and a 10 mm bearing plaster is provided at the base, no cracks will appear in the RCC roofing.

Hand mixing of concrete
Indian specifications sometimes allow 'hand mixing' of concrete. Whatsoever, precautions you may take, hand mixing will not produce desirable blending of concrete ingredients. Cement consumption will also increase. Water-cement-ratio will also not remain under control. Therefore, avoid hand mixing. If unavoidable, allow it for lean concrete only. Non-uniform mixing of ingredients in hand mixed concrete means lack of workability, strength and density of concrete.

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 a double loss on use of undesigned 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.

Click on "Full Story" For Read These Points..

• Reinforcement in beams

• Non-usage of admixtures