What Causes A Roof To Leak?

We Have All Been There

It starts to rain and you hear the unmistakable pit pat of a previously unknown leak, or you start noticing patches of damp along your walls, making you want to cry with frustration. There are a number of reasons why your roof could be leaking. But once you know what could be causing the leak, it is easy to repair and take precaution that it won’t happen again in the near future.

The Top Causes Of Roof Leaks

Age of Roof

This is one of the main causes of leaking roofs. Nothing lasts forever and roofing is no different. With age, your roof will begin to slowly break down. Nails begin to rust and concrete tiles, because they are porous, will de-construct themselves and start to crumble over time. Broken and cracked slates or tiles expose the timbers underneath and water starts to rot the timber structure of the roof.

The Weather

Related to age, weather can cause a lot of damage to your roof over time. The sun, rain, sleet, ice and snow all affect your roof. The sun tends to dry out roofing paper and to cause the tar to run and sag which weakens your roof covering. This then starts to become brittle and will begin to crack and split. Extreme weather changes also cause the roof to expand and contract, adding further damage to the roofing materials and eventually leaks start to appear.


During particularly cold snaps, ice that gathers on your roof eaves can cause an ice dam. This then blocks the correct flow of water from your roof, causing it to collect under the flashings and tar paper. This then overflows into your house, dripping for days as the heat from your home slowly melts the ice.

Faults in the Flashing On The Roof

Wind and rain exposure can cause the caulking used to seal your roof flashing to dry out and the seal between water and your roof is broken. To prevent this kind of leak try poking around the flashing that is found around your chimney, vents or roof windows to see that it is still sealed tight. If not made from lead, rusted flashings can also be an eventual cause for roof leaks. Prevent rust by using rust resistant paint.

Clogged Gutters

Leaves and debris can gather in your gutters and clog them up, preventing free flow of the water from your roof. In winter this can become even more of a problem as the water clogged in the gutters may freeze and cause an ice dam. A simple solution is to check your gutters are cleared regularly, especially before winter.

Poor Roof Construction

Cost cutting in roof construction can lead to a number of problems. Inadequate insulation, use of lower grade roofing paper and rushes to hurry a job to fit a deadline all mean that your roof could start leaking well before it should. Always make sure you hire a reliable roofing contractor and check the quality of your roof when buying a new home.

Plumbing Vents

Age and weather exposure can cause the seals on your plumbing vents to split. The result is water spraying out and affecting your roof. Remember to have your vents inspected for signs of wear.

Wind Blown Rain

Rain doesn’t always fall straight down and wind blown rain can be really problematic. Because the rain is coming in at an angle water can get under your roofing materials. Make sure you account for wind blown rain when laying your roof tar paper.

Roof Coating

Make sure you check the waterproof coat of your roof.  If sealant has not already been applied in recent years, it may be time to do it.

Damage To Roof From Mechanicals

Although technically they have nothing to do with your actual roof, heavy pieces of technological equipment such as air conditioners and antennas can cause some damage. Not only do they put extra weight on your roof but each time you have something installed or repaired, you are inviting contractors to walk all over your roof which could lead to breakages you may not know of.