Common Leak Sources

Leaks can occur just about anywhere, but certain patterns show up again and again. This is by no means a comprehensive list, but the majority of leaks will fall into one of the following categories:

1.   Flat Roofs:   A flat roof is not supposed to have areas that are truly level. Everywhere should have a slight slope that guides water to one or more drainage points, but as the roof ages it can warp, creating pockets of standing water. This is an extreme test for any water barrier, let alone an aged roof with an aged roofing membrane that is starting to perish and it only takes a pinhole to be a serious problem. As a general rule, the lower the pitch of a roof, the easier it is to interfere with water runoff and create a potential leak.

2.   Decks and balconies:   These are flat and nearly level, so water is slow to run off and easily ponded by the slightest barrier, just like the flat roof. Unlike the flat roof, they are frequently walked on, which increases the stress. Consequently decks and balconies are one of the most common places for leaks.

3.   Valleys:   The angle where one down-sloping roof surface meets another is called a valley. Valleys have a higher volume of water flow because runoff is channeled into them from two directions. The valley should have metal flashing that goes up under each surface. Where the valley is blocked by leaves or other debris, the water will tend to back up under the roofing, and if it backs up enough to go over the flashing it can get into the structure. 

4.   Roof and Vertical Wall:   Where the roof slopes down into a wall, this is similar to a valley, and the worst case is when they meet at an angle parallel to the ground. However, it’s also possible to have problems when the roof slopes up to a wall. This occurs especially when an addition brings a new roof up against an existing block wall, because the new flashing is often put against the outside of the block wall, which is porous and lets moisture get behind the flashing.

5.   Vents:   The roof in most buildings is penetrated by a number of vents. There are vents for hot water cylinders and industrial vents for furnaces and kilns etc. that let gases escape. There are vents for plumbing that equalize pressure in the drains. There are ducts for roof-mounted air conditioning units. One thing these have in common is that they break through all layers of the roof membrane (see Note below), and wherever that occurs you increase the potential for leaks. Also, vents should have flashing that goes under the top layers of roofing on the uphill side, and over all layers of roofing on the downhill side.

6.   Lack Of Maintenance:   There are many reasons not to neglect the roof – including financial and business continuity reasons. Being wise to problems can prevent their escalation. Perform routine inspections or get  a CITYWIDE Maintenance Plan and we’ll inspect your roof anually, or as required. Addressing minor problems before they escalate maximizes your roofs life as well as minimizes headaches and expense.

7.   Chimneys:   Unfortunately, chimneys combine the leak hazards of several sources we’ve already mentioned. Like vents, they usually break through the roof membrane. Because they have vertical sides, they duplicate the disadvantages of #3, Roof and Vertical Wall. And unless the chimney goes through at the ridgeline, on one side the roof and chimney will create a valley parallel to the ground. It’s common practice to put a little gable or v-shaped flashing, called a cricket, on the up-slope side so that water will run off and around the chimney, but this is by no means universal. Chimneys are also often made of bricks and mortar, which is porous. The exterior surface of a brick chimney should be water-sealed every few years, which is seldom done, and every chimney, regardless of materials, should have a rain cap.  

8.   Deteriorated roofing materials:   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 tiles expose the timbers underneath and water starts to rot the timber structure of the roof.

9.   Mechanical damage:   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. Most causes of leaks can be avoided by regular checks and general maintenance on your roof, call in CITYWIDE and a professional roofer will do the job to a very high standard for you.

10.   Groundwater:   This is actually a whole class of problems by itself, but most groundwater problems are one of two types. First is intrusion from surface water, whether from rain run-off or sprinklers. Moist soil is in contact with the building walls and the moisture is seeping through. The second type of problem is where hydrostatic pressure is forcing water up through the foundation or footings. This water may originate some distance away from the structure. In either case, the solution requires careful analysis of the causes, and usually a combination of remedial actions.

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