Rainproof your home

For the past three weeks, rains have been pounding several parts of the country much to the delight of everyone after a protracted and unforgiving dry season.

While the onset of rain means grass lawns will blossom, the green vegetation cover will return everywhere and farmers will have a reason to smile, excessive rain, like we are currently experiencing, can be disastrous and costly to home owners. Homes can be exposed to damage, and this would mean incurring extra expenses on repairs. 

“Rain can enter into a building through breaks in the roof, or through porous building stones that let in moisture from outside or through the foundation moisture trapped below the ground floor slab,” says Mr Francis Gichuhi, an architect and founder of architectural firm A4Architects.

He notes that if water makes way in a home through walls and roofs, it can easily damage the woodwork, enabling the growth of moulds, allowing condensation and eventually leading to the erosion of brickwork.

“Damp patches besides making the house look ugly have the potential to spread fast and become a cause for concern health-wise,” he says..

Therefore, you should closely scrutinise the condition of your roof and gutters and assess if there is any need for repairs, and simply hire an expert to do the job.

Normally, a missing tile, broken roof tile or iron sheet means your house is exposed to harsh weather.

Though normally the roof of a house is extended outward a bit to shield the wall from harsh weather, painting your exterior walls prior to rainfall with quality water proof paints will not only dictate the look of your house but will also create a protective layer on the wall.

“Do not hesitate to use water proof paints on wooden walls to prevent water from seeping into the walls and corroding it,” advises Mr Gichuhi.

Besides paint, Mr Gichuhi says material such as mazeras, stone tiles or cement plaster will go a long way in protecting the brickwork.

He adds: “For earthen structures, bituminous paints covered with cement plaster will go a long way in protecting the interiors from rain damage.”

GUTTERING

Gutters make for a significant element of the roofing system and their role include gathering and funneling away water on the roof, securing the home’s exterior surfaces and preventing water from entering.

Without gutters, rain water could make the wooden fascia board susceptible to rot if it comes into contact with it, says Mr John Wainaina, a construction manager with In House Ideas Ltd.

Additionally, while wooden fascia board could rot, homes with plastic facial board could lose their aesthetic appeal as polyvinyl chloride (PVC) fascia boards tend to discolour with time when rained on. 

“Rain water from the roof has the tendency to collect at the ground creating run off that is likely to cause a drainage problem in the homestead. If you can stop the water from draining from the roof to the ground, then your problem will be half solved. How you do that is by using gutters and drainpipes,” says Mr Wainaina.

As a precautionary measure before the rain starts to pour, make sure that the guttering outside your home isn’t leaking or broken, and remove all debris or leaves that get collected in it and block the passage of water. If the problem is overlooked, then the gutter may overflow and will aggravate the problems.

The advantage of using gutters is that you can direct the water to a tank for use in household chores like cleaning, washing, while at the same time saving on the metered water.

PROTECT YOUR ROOF

There is an old aphorism that says, “prevention is better than cure”, so in that spirit if you are building a new home, buying genuine roofing materials is a good place to start, notes Mr Wainaina.

“Roofing technology has really improved and nowadays we have mabati that come with a coating of zinc and aluminium, or even stone coating, and these materials can last up to 50 years or more. No amount of rain can affect that alloy and so if you just buy genuine roofing sheet, you will be starting on the right footing,” says Mr Wainaina.

He notes that perhaps the most important aspect of roofing is to ensure that the mason who installs the roof is  qualified so that he or she does not damage the roof.

On the other hand, some houses normally have a flat concrete slab acting as the roof. Such a roof would need to have a water proof layer on top to make sure water does not penetrate through to the house. Also, the roof should be cambered so that it is tilting towards a drainage point.

THE COMPOUND

The most effective way to reduce the effect of run-off according to Mr Wainaina is to have grass and trees covering the ground all around your compound.

Consequently, he adds, if your compound lacks vegetation cover, gravel will be a good alternative to slow down run-off and prevent soil erosion. “And while at it, ensure the water ways are cambered to allow water to flow down naturally to a waiting soak pit or the county council’s storm drainage system,” he adds.

House under construction 

If your house is under construction, experts advise that you should ensure the contractor adheres to certain principles that will see your house withstand harsh weather in future.

“For walls, a minimum of 200mm nine inch thick stone wall should be used for the external walls to prevent moisture from percolating through the stone. For foundations, a damp proof membrane is put in between the ground floor masonry stone and the floor slab to prevent moisture from being sucked upwards through capillary action. A plastic PVC 500 gauge membrane is also placed on top of the hardcore before laying of the slab to ensure no moisture is sucked from below onto the ground floor slab,” says Mr  Gichuhi.

The architect adds that a one foot thick hardcore base is also set up in the foundation to soak in water, ensuring no moisture gets sucked on to the ground floor slab.

For roofs, care should be taken to ensure the roof covering has adequate overlap, is set on the recommended pitch slope and there are very few valleys where rain water from two different slopes meet, so as to avert an over-flood.