A building does not become a shelter until there is roof on it. Before you can move in to you house the roof must be in place to protect against rain, sunshine and other weather elements that will make you uncomfortable. To get a workable roof you must prepare it from the design stage, this is why is important you get an architect to design your house for you. Ask the architect to explain the falls or pitch of the roof to you and the workability. If you can get a model or 3d design of your building showing view from top will be good, but this may cost you more in cost of design.
(1)Too much of parapet walls. Too many walls jutting out to stand alone on the sky without the roof covering may be difficult to achieve and the cost of treating is high, unorganized parapet walls in a building is a sign of less dexterity on the part of your designer/architect, and this brings a lot of trouble during and after construction of your building. Managing parapet walls can be hard and atimes awkward. The parapet cap must be covered by aluminium or concrete coping/cap. The joints where the roof elements meets the walls must be properly treated with aluminium flashing or bitumen, which makes the roof to look ugly especially if not properly handled. Leakages are prominent with parapet walls.
(2)Non application of bituminous felt or aluminium flashing where necessary. Just as it was said above these materials helps to prevent leakages especially at the joints where roofing sheets and walls meet.
(3)Very low pitch roof . When the gradient or slope is too low it will affect the speed of the movement of water on your roofing sheets, therefore for a not well properly knitted roof, the roof will be susceptible to leakages because of slow speed of water dropping off the roof. In otherwords, let your roof be as high as you can afford and possible.
(4)Overtrust in your carpenter. One of the greatest mistakes you will make is to trust your carpenter capabilities when it comes to roofing. Few carpenters can read designs and when it comes to roof it becomes more complex so you need a professional to explain or supervise your roof.
(5)Also trusting your carpenter with money because he had been truthful from the start of your project can be your greatest undoing. The carpenter knows he stands a chance of making more money if he can be able to secure the roof contract, so he may decide to play holy from the start of your project, so giving him money to buy wood for you without proper monitoring or when he brings the wood to site you decided not to count because you now trust him may turn out to be a grave mistake. He knows the numbers of the wood are much now and you may probably be reluctant to count them considering the volume especially when you now trust him. The carpenter knows he may never have to work again for you after the completion of the project, so he sees himself as having nothing to loose, the only reason he won’t do that is when you are a building professional yourself, he knows if he does that he has blocked opportunities of more jobs from you. Artesans rarely believes in your refferal power as a layman.
(6)Designing your roof to direct water on walls in your building. By this I mean pointing the rainwater to drop water directly on your walls will mess up the walls under one year of building, it will make the wall to turn greenish or blackish and you may have to be repainting every year. Make sure you point this out to your architect.
(7)When your walls are too close to the adjacent house. It is required you leave a considerable space between your building and the adjacent one, if not when you finally put your roof and is having an overhang of 600mm/0.6m/2ft, the water may drop into the walls or windows of the next door neighbour which will bring so much discomfort during rainy season.
(8)Don’t buy woods and install on your building when you are not ready to cover it up with roofing sheets the wood will expand and then shrink because of continous rain and sun beating it which will make it difficult for the roofing sheets to be properly placed when you are finally ready to install.
(9)Make sure the gutters are well placed and treated .
(10)Overdesign and complex roof will also be difficult to execute properly, hence if you know you aren’t ready to pay workers the extra cost for their patience don’t go for complex roof, it will also cost you more of materials.
(11)Make sure all loose nails on top of roofing sheets are removed.
(12)Check every nail holes and cover them, if not there will be leakages.
(13)Finally recheck during rainy season for any leakages before installing your ceilling.