Roofing tiles

Broken or loose roofing tiles are easily repaired. However, if the gap in the roof covering goes unnoticed serious structural damage may occur. Water may channel down roof rafters causing serious damage before the leak is noticed inside the property.

Roofing tiles are often removed from the roof by wind pressure. Contrary to popular belief the roof tiles are not normally "blown off" the roof. The wind creates a vortex which causes the roofing tiles to be sucked upwards. This may seem unimportant as the net result is still a leaky roof. But in order to prevent future tile loss, it is important to understand how the wind affects the roof covering.
As the wind moves over the roof, it causes the pressure on top of the roof to decrease. Simultaneously, the pressure inside the attic increases. This lack of pressure above the roof causes the tiles to be sucked upwards. The lower the pitch of the roofing, the higher will be the suction above the roof.

It is easy to see how tiles can be lifted upwards. The traditional method of fixing tiles is to nail the very head of the tile. This works well against the pull of gravity but is not as effective against wind uplift. The roofing tiles are constantly lifted and dropped as the wind moves over the roof. It is this effect that causes "tile chatter" and eventually leads to broken roof tiles. If tail fixing is not employed, the only security is the dead weight of the tile itself.
Extensive wind tunnel tests carried out in the United Kingdom showed that a roofing tile fixed at the tail can withstand five times the upward lift of a head nailed tile. Roofing manufacturers have taken this information on board and most supply tail clips with their products. It is important to note that tail clips are an addition to tile security and should not be used to replace head nailing.

The biggest weapon the roofer has in his armoury against wind pressure is often overlooked. The number one purpose of roofing felt is to stop wind uplift. The waterproofing qualities of roofing felt are secondary. If the paper is laid correctly it will stop the rise in pressure inside the loft area. It should be laid tightly with sufficient laps to provide a wind seal. Further, the laps should be sealed down extra tight. An extra baton should be used over the laps to ensure that no wind is allowed to enter or exit the loft.
All ridge and hip tiles need to be securely fixed in areas of high wind pressure. Roofing Cement should not be relied upon to hold ridge tiles in place. Once the bond between tile and mortar is broken the roofing tile can work free. They should be nailed, clipped or wired to a baton.
The areas most lightly to be subjected to wind uplift are the perimeter. In these areas it is wise to take extra precautions with your tile fixing. Nail and clip all tiles around the eaves, verge and ridge. This will ensure the roofing tiles stay on the roof and provide you with extra piece of mind during heavy storms. Click here for more information about roofing and roof repairs.