FLAT ROOF LEAKS

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Like any roof, in time, after wear and tear and weathering, flat roofs will eventually leak.  No roof will last forever and if you have a roof over your head, it will most likely leak someday.  This is perhaps all the more true of flat roofs, because water doesn’t run off of the roof surface quickly and can easily find breaks in the roofing surface resulting in leaks. Flat roofs are a common feature in many homes and often require more work than any other standard types of roofs.  Though flat roofs are simple to build, it requires a lot of maintenance and inspection so that everything is functioning as it should.

If you own a property with a flat roof, it can be daunting task to diagnose and resolve a problem if you suspect leakage.  Leaks don’t always mean that your entire roof needs to be replaced.  The most common and most challenging part of dealing with flat roof issues is figuring out whether you need to get it replaced or if it just needs a few minor repairs.

Long before a flat roof leak occurs, there are numerous warning signs you should keep an eye out for.

• Damp, dark brown patches on the ceiling indicate that moisture is seeping through your roof, which could become a major issue if not dealt with swiftly.
• If your flat roofed garage or extension is quite old and exposed to the elements, you may notice your flat roof sagging or dipping.  This is an indication that the timbers have begun to rot and will eventually give way, meaning a full flat roof replacement may be in order.
• Be on the lookout for low spots atop your flat roof, as water can pool here, placing undue stress on the structure below and slowly disintegrating the chipboard decking through exposure to excess moisture.

Common Problems that Can Cause Leaks in Flat Roofs

Flat roofs are more complex than they might seem.  There are many common causes of roof leaks.  Some of these can be controlled, such as choosing the right material, or installing your roof correctly.  However, as time goes on, exposure to the elements, such as harsh weather or extreme temperatures, will place stress upon and eventually break down even the most well-built roof.  There are several common causes for flat roof leaks, and each of them can occur in various situations:

• Standing water on the roofing surface
• Roof is located in a harsh environment
• Utilizing outdated roofing technology

Ponding Water

Standing or “ponding” water is one of the most common issues faced by flat roofs.  It is characterized as any water that remains on the roof for longer than 48 hours following precipitation.  The longer the water remains on your roof, the greater the chances are that it will lead to damaging leaks.  The roof should be designed with a slight slope so that water can easily find its way to the drain points.  Sometimes we find that even flat roofs that were carefully designed in this way can eventually be faced with ponding as they age.

It is important that you regularly monitor your roof for any signs of standing water.  Gutters, downspouts, wall scuppers and drains will lead to ponding if not functioning properly.  Ponding is more likely to occur around large rooftop units because the weight of these structures will prevent the structure of the underlying roofing supports from working as designed, leading to ponding.

Be aware that, even if ponding doesn’t lead to leaks, it still represents a significant roofing problem.  The reason for this is, as time goes by, the enormous weight of standing water will gradually make the problem worse.  Roof leveling can resolve minor drainage issues, but more serious issues of ponding require changes to the underlying roof structure itself.

Leaks and Moisture

Another common problem with flat roofs is leaks.  But since it’s a flat roof, the water doesn’t have anywhere to go but straight down.  This means that the moisture can seep into the roof that may cause mold and fungus, or damage to the structure.  The best way to overcome this issue is to get your roof inspected regularly so that it can be maintained every time there is an issue.

Damaged Roofing Membranes

Until several years ago, flat roofs were made of multiple layers of asphalt tar, roofing felt and gravel.  This was an effective approach, but is time-consuming to install. So, nowadays, roofing membranes are the more popular choice of the business owners.  These membranes are made of a very thin single-ply membrane, generally made of durable rubber. In comparison to built-up roofing these membranes are less expensive and easier to install.

But, like any other roofing system, these membranes are prone to damage as time goes by.  Cracks, blisters, and splits are some common problems.  These cracks and splits allow water to accumulate beneath the membrane and once the insulation becomes waterlogged, it will lead to difficult to identify causes of leaks. For this reason, you should get your roofing membrane inspected regularly for signs of damage.

Damaged or Deteriorated Flashing

Like most other materials, asphalt flat roofs expand and contract with changing weather.  With time, this continued process of expansion and contraction will cause the flashing to pull away from the corners and edges of your roof.  The flashing faults will lead to leaks, and moisture can easily get trapped inside the roof.  The best way to avoid this is to get your flat roof inspected regularly and repaired as necessary, because if the leaks become significant you will have no other choice except to get a new roof.

Flashings are a key part of any flat roofing system.  Their job is simple, to cover and seal any angles, seams, or joints, that would otherwise provide the perfect place for water to enter. This could be along an adjoining wall, around roof vents, and more. However, despite its impressive lifespan, flashing can falter, particularly when exposed to extreme temperature fluctuations.  Over time, as the metal heats up and cools down, it will expand and contract, eventually revealing the edge it was meant to protect.  This then, in turn, causes flat roof leaks.

Cracks in the Roof

Flat roofs tend to have more pressure exerted in comparison to sloped/slanted roofs. When this pressure becomes excessive, it can lead your roof to crack.  As soon you see any crack in the roof, call a roofing contractor immediately.  Not only will a crack expose the roof structure – or potentially even the interior of building – to precipitation, but it is also a sign that your roof is structurally compromised and it’s the right time to get it repaired or replaced.

Age

No matter how well they were made, or how perfectly they were installed, all roofing materials will deteriorate over time.  Harsh weather conditions, extreme temperatures, sudden impacts, all of these things will eventually wear away at your flat roof until it is damaged and begins to leak.  However, in recent decades, manufacturers have made great strides to advance the strength and longevity of their flat roofing products, which today far outdo those of decades past.  Simply put, your flat roof may be leaking because it has reached the end of its useful life.

Thermal Movement

In the second half of the twentieth century, oxidized bitumen was used as an adhesive to stick rubber roofing membranes onto flat roofs.  This had many advantages, however, due to its rigidity, oxidized bitumen has very little movement.  Therefore, when temperatures change, it cannot expand or contract as necessary, leading to cracks, blisters, and splits in the membrane above, and eventually causing leaks.  Many older flat roofing systems were also designed before expansion joints became widely used, which facilitate effective thermal movement to prevent membrane failure.

Poor Installation

Even the most well-crafted flat roofing materials will not perform correctly if they are installed poorly.  Flat roofs are highly vulnerable to leaks due to their near non-existent pitch, and many weak points.  Therefore, it’s vitally important that any flat roof is installed according to the manufacturer’s guidelines.  Find a qualified professional roofer to install your flat roofing system.  While it is more expensive, this prevents future maintenance costs and gives you peace of mind that your flat roof is nice and secure.

Seams and Overlaps

One of the most common areas where flat roofs fail and spring leaks are the seams or overlaps between different pieces of flat roofing material.  This is especially common where the overlap has not been sealed correctly, as water will quickly find its way between the two layers.  Seams and other joins such as overlaps are natural weak points that water can attack and should be closely inspected at least twice per year to ensure no future problems are on the horizon.

Blistering

Blistering is a common issue with flat roofs.  If you spot raised blisters along the surface of your flat roof, it’s a strong sign that water has gotten underneath your flat roofing material.  As the water seeps down, it becomes vaporized by the higher temperatures below, this water vapor then rises, but with nowhere to escape, the pressure causes blisters.  Blisters are generally caused by water ingress, where rainwater or other precipitation finds its way into a weak point of your roof.  Alternatively, blisters could be caused by damp timbers or insulation, as well as condensation.  Blisters are a weak point in your flat roof, and when they burst can cause significant roof leaks.

Delamination

Delamination occurs when the different layers of flat roofing membrane separate, becoming “delaminated” from one another.  This can lead to all sorts of problems, including cracks, splits, and even blistering as water seeps into and between the two layers of material.  Delamination is generally caused by poor workmanship during installation, when the layers are not heated enough to seal correctly, or when water gets in between the layers and builds up inside.

Detailing Around Vents

Some of the most common areas where you’ll find a flat roof leaking is from poor detailing around or damage to raised sections such as the area around roofing vents, gas lines, pipes, and more.  Just like seams and joins, these present yet another weak spot for water to attack your flat roof should they not be correctly sealed. Once again, this stresses the paramount importance of finding a qualified roofer to install your flat roof if you don’t think you’re up to the task.

How to Find a Leak in a Flat Roof

Finding the source of a leaking flat roof can be tricky.  On a pitched roof, it can be as simple as tracing the leak to materials directly above, but on a flat roof, water can travel in all directions between the layers in your roof space before leaking into the rooms below.  If your ceiling is damp, stained with water, or dripping, it does not necessarily mean that the roof leak is directly above.  To find the source of a leak in a flat roofing system, you’ll need to get up and inspect the roof.

The best time to look for a leak in a flat roof is when it has been dry for at least 72 hours, ideally in the evening. This is because as the temperature drops, the source of your flat roof leak will gently steam as heat is released from underneath.  You should also be on the lookout for low spots surrounded by a ring of dirt, which suggests pooling water was there previously.

Once you’ve found your suspected source of the roof leak, use a hosepipe to gently spray the area, and then go back down and see if the leak reoccurs.  You may have to wait a bit, as the water will have to navigate its way through the many layers in your flat roofing system.  This method is highly effective, but takes time, and you may not find the right spot on your first try.  While you’re up on your roof, you should give the whole thing a thorough once-over, to ensure there is no damage that could cause roof leaks or other issues in future.