Flat roofs are not a buy and forget product. Flat roofs require yearly attention and monitoring of any potential problems. The first priority for the homeowner is to establish a relationship with a roofing company you trust because you need to schedule frequent inspections throughout the year and especially after every heavy storm or hail storms. We'll cover the following problems with flat roofs: Standing Water, Biological Growth, Accumulated Debris, Weight Capacity, Vulnerability to Wind Gusts, Blistering, Alligatoring, and Shrinkage.
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Homeowners pay for a flat roof with the expectation it will last at least 15 years. Unfortunately, most flat roofs only last around 10 years. Today, we'll cover the problems you will run into with your flat roof and how to deal with these problems.
There are a variety of roof technologies, but they all fall into one of two categories:
Flat roofs require a roofing company that will water proof your flat roof. The company you hire must be obsessed with water proofing details and you must quiz them on water proofing before they earn your business of installing your new flat roof. I've met many expert roofers that have been in the business so long they have gotten complacent and overlook specific details when installing pipe jacks or skylights. These are perforations to the roof that will be the main source of leaks, if not done correctly.
This is a huge problem, even though it sounds completely normal. Standing water weights 62.4 pounds per cubic foot and puts incredible pressure and load on your flat roof. Mold and fungus will grow quickly. The water will attract animals, insects, and rodents; all of which will directly contribute to the deterioration of the roof. With enough water and not enough support, your roof is sure to collapse as we demonstrate later in the article. It's evident the water ponding is a big issue to the roof, but it also causes problems to the foundation of your structure. The water isn't draining properly and not being guided to the optimum location away from your home.
Ponding is a sign of a larger issue at hand, which is lack of optimal water shedding away from the structure of the house. Invest in the repair along with downspouts guiding the water to the sidewalk.
Plant life will thrive with standing water. Soon enough, a tree could dig its roots into the roof. Flat roofs need to have a slight slope to guide the water away to the downspouts. Try to control the direction of the water flow as much as possible. This should be planned before the roofing company begins the installation. Planning is attributed with 90% of the success of your flat roof project.
There is a roof system called a green roof where they intentionally grow vegetation on top of the flat roof, but that isn't covered today in this article. Just for fun, we included an image of a house in Norway where is it common to grow trees on top of their pitched roofs. Go Norway, you can have that trend! I hope it doesn't get popular in our neighborhoods.
Neighborhoods with mature trees will make things difficult for your flat roof. The trees will have an over abundant supply of debris falling onto your flat roof. To minimize this problem, keep all trees trimmed so the branches don't get within 10 feet of your home. The flat roofs allow branches, leaves, and other debris to accumulate on your flat roof and blocks the drainage system. In addition, a large pile of leaves traps moisture. In the winter, the leaves go through a cycle of freeze/thaw, then refreeze throughout the winter season. Meanwhile, your flat roof is aging and having a reduction in shelf life.
The integrity of each element of a building is critical to its stability. However, no component carries more potential for property damage or personal injury than the roof. A poorly performing foundation or failing exterior cladding can be inconvenient, unsightly, and expensive to fix. An overworked roof collapsing can ruin your financial health and long-lasting consequences.
There are telling signs of stress you should not ignore. Becoming familiar with the signs can prevent serious damage. The telltale signs that point to problems with the roof’s materials, design, functionality, or all three are usually only visible on the roof itself. Most people don't have roof inspections every year or after every storm; so, to them, it's a surprise but it doesn't have to be one. Property owners can help protect themselves from costly repairs and legal liability by becoming familiar with these signs and calling on forensic engineering, a trusted and knowledgeable roofing company.
There are many negative consequences from roof collapses or any kind of structural failure, it is imperative to design houses and buildings using the latest industry standards. Those standards are the International Building Code (IBC), with strict interpretation to loads and material strength provided by the American Society of Civil Engineers (ASCE) Standard 7 – Minimum Design Loads for Buildings and Other Structures.
These standards detail how roofs should be installed and the details to sustain two different types of loads.
Flat roofs are many sheets of material combined to form one waterproofing membrane, a little wind damage can turn into serious wind damage with just a few gusts of wind. The whole roof can peal off and require immediate need for replacement.
Below is an image of how wind affects the flat roof. As the wind passes through your home, it creates lifing forces that can peal away the flat roof membrane.
Blistering, a type of flat roof surface defect, occurs when air (sometimes water) gets trapped between the cap membrane layer and the base layer. Blistering leads to guaranteed roof failure over time. The bubble like effect is worse in the day when the sun's heat causes it to enlarge. Please don't ignore any of these problems because the problem can skip the ability to be repaired to the worst case scenario which is the full replacement of your roof.
Alligatoring is a type of blistering. It could be that alligatoring occurs in areas where the constant expansion and contraction of the membrane dries out the cap layer to this extreme. Alligatoring occurs after the initial blistering shown in the previous images.
Shrinkage is guaranteed to occur on flat roofs made from synthetic rubber membranes, such as EPDM. It causes seams to delaminate and separate which breaches the waterproofing and renders your roof useless.
Though EPDM is a popular choice in the construction of flat roofs due to its durability, all EPDM roofs will eventually experience shrinkage. Manufacturing or installation defects serve as the catalyst to the natural shrinkage expected from the this roof technology.
Have your flat roof inspected yearly. It's best to monitor and stay proactive on cracks or fissures on the flat roof membrane.
In particular, look for cracks around ridges. Imperfections appear on flat roofs over a period time due to water exposure and extreme weather. It's always better to be safe than sorry, so pay attention to detail. Hire a roofing contractor you trust to help you with honest inspections. Having a leaky flat roof can be prevented.