Paope of flat roofs: why should it be and what should be?

Even though they are sometimes disregarded in favor of their sloped counterparts, flat roofs are essential to modern architecture. In addition to adding to a building’s aesthetic appeal, their simple, minimalist design has useful advantages. Flat roofs offer a flexible surface for a range of applications, from solar panel installations and HVAC units to rooftop gardens and outdoor lounges. Pitch roofs, on the other hand, are inclined.

Weather resistance and durability are critical factors to take into account when choosing materials for flat roofs. The lifespan and functionality of the roof can be greatly impacted by the selection of materials. Modified bitumen, TPO (thermoplastic polyolefin), PVC (polyvinyl chloride), and EPDM (ethylene propylene diene terpolymer) are examples of common materials. Regarding cost-effectiveness, ease of installation, and maintenance needs, each material has specific benefits.

For flat roofs to work well, proper installation is essential. In contrast to sloped roofs, which naturally release water and debris, waterproofing and drainage on flat roofs need to be done with great care. Proper drainage keeps water from collecting, which over time can cause leaks and structural damage. Waterproofing membranes aid in preserving the integrity and lifespan of the roof when paired with routine maintenance and inspections.

Another crucial component of caring for a flat roof is maintenance. Frequent inspections make it possible to identify possible problems early on, like cracks, punctures, or failing seals. Timely maintenance can stop small issues from growing into more expensive fixes or an early roof replacement. Furthermore, maintaining adequate ventilation and removing debris are crucial maintenance chores that support the general well-being and functionality of flat roofs.

Why do you need a parapet on a flat roof

On a flat roof, the parapet serves eight purposes simultaneously:

  1. Frightens the roof. The parapet prevents a random fall from the roof.
  2. Protects the roller roof from the wind. No matter how well the roll waterproofing coating is glued, without a parapet, the wind will quickly begin to tear it up at the edges of the roof. And the higher the building, the faster it will happen.
  3. Prevents the fire of the roof. The parapet does not burn, so the flame tearing out of the windows during a fire is more difficult to spread to the roofing material.
  4. Part of the drainage system. The parapet of the flat roof prevents an inorganized gutters, holding the water on the roof until it drains into special funnels.
  5. Ensures the safety of the roof for passers -by in winter. The parapet does not allow the snow to go with layers and reduces the number of icicles along the edge of the roof.
  6. Hides elements of roofing infrastructure. Parapets on a flat roof of modern buildings play the role of a decorative screen, closing the air conditioners, wiring pipes, deflectors and other technical elements of the roof from the eyes of passers -by.
  7. Serves as the basis for the installation of lightning protection. When organizing lightning protection of the building, its elements are attached to high areas of the roof and along its perimeter.
  8. Provides safe installation of antennas and other similar devices. Satellite, television or Internet antenna can be attached to the parapet without damage to the roofing.

For people’s life and safety, a flat roof parapet serves at least three essential purposes. Therefore, one-story houses are the only ones that typically have roofs without such a fence. And then not every time. Despite the fact that the standards contain gaps that let you operate without a parapet in some situations.

Do you always need a parapet on a flat roof?

Two standards primarily govern the height of the roof parapet, the installation guidelines, the design, and other aspects:

  • SP 17.13330.2017 "Roof";
  • SP 4.13130.2013 "Fire Protection Systems".

They claim that the operated roof’s parapet is essential. It is simply necessary for the building to function.

But options show up if the roof is not explosive.

As mandated by SP 4.13130.2013, safe fences have to be installed if:

  • The slope of the roof is 12% or less, and the height of the building to the cornice overhang is more than 10 m;
  • The slope of the roof is more than 12% at the height of the building more than 7 m.

That is, a parapet cannot be added to a two-story building with a flat, immovable roof, for example. On the other hand, a steel fence is frequently required to ensure the security of roofing.

For any building, selecting the proper kind of flat roof is essential because it affects both longevity and upkeep expenses. This piece examines several flat roof choices, stressing pros and cons of each. Property owners can improve longevity and performance and meet specific architectural and financial requirements by knowing the differences between materials such as EPDM, TPO, and built-up roofs.

How the parapet works

A flat roof’s parapet is made up of four different components:

  1. The enclosing side itself from brick, gas block or concrete.
  2. Fillet – triangular in the cross section of the transition element between the horizontal surface of the roof and the vertical wall of the fence.
  3. Protection of the end of the parapet – metal visor or concrete, stone or ceramic slabs that are placed on top of the parapet to protect it from precipitation.
  4. Waterproofing apron – several layers of waterproofing, which are wound on the parapet for sealing the place of junction.

Flat roof parapets can occasionally come with an extra steel fence or transparent material, such as polycarbonate or tempered glass. In addition, since the side is typically low, you can guarantee the security of individuals on the roof with this solution without obstructing the view from it.

In the event that a sports or children’s area is constructed on the roof, a strong, high-grade grid is used to further seal off the surrounding area. Another name for it is "catching." It’s necessary to keep people from falling and to hold onto balls and other equipment.

What should be the height and thickness of the parapet

The parapet is regarded as an extension of the house wall. Its thickness should therefore be roughly the same. Narrowing the enclosing side in relation to the wall beneath it is acceptable, but it must be minimal.

Concerning the height, the operated roof’s parapet should be 1.2 meters high in accordance with SP 17.13330.2017. It’s more challenging when the roof is non-explosive.

A non-combined fence that is at least 0.6 meters high should have a non-combined roof from a fire safety perspective. However, the focus is on the fence rather than the parapet in particular. That is, it can be a single, high-height steel railing or an entire brick side. But only if the roof contains the external drainage system.

For a flat roof, the parapet is always required in order to collect water if the drain is internal. Additionally, the minimum height is determined by the volume of precipitation and the water column system’s estimated throughput. Put simply, the height of the parapet needs to be high enough to prevent water from overflowing through the side, even during periods of intense precipitation combined with a storm wind. In this instance, the roof’s minimum parapet is typically between 0.3-0.45 meters.

Selecting the appropriate inclination for a flat roof is essential to its functionality and durability. Although flat roofs give the impression of being level, they actually have a small slope to allow for proper rainwater drainage and avoid pooling. This slope is usually very small, about ¼ inch for every foot of roof. Water can move toward gutters or drainage points on this mild gradient, which lowers the possibility of leaks and long-term structural damage.

The ideal slope is also influenced by the material chosen for flat roofs. For instance, because of their asphalt layers and waterproof membranes, built-up roofs (BUR) and modified bitumen roofs can withstand lower slopes. However, slightly steeper slopes are necessary for single-ply membranes, such as TPO or EPDM, to allow for efficient water runoff. Knowing these subtleties makes it easier to choose the right slope that complements the architectural style of the roof and the climate in the area.

The intended use of the roof, local climate, and building codes are all important considerations when planning a flat roof. The minimum slope needed to comply with water drainage regulations and avoid water damage is frequently specified by local building codes. A steeper slope might be required due to climate conditions like heavy rainfall or snow accumulation in order to ensure effective water shedding and avoid structural overload.

In the end, a flat roof’s slope greatly affects how long it lasts and how functional it is. In order to minimize maintenance and maximize protection against water-related issues, homeowners and builders can ensure a flat roof that functions reliably over its lifespan by carefully determining the correct slope based on the materials of the roof, local regulations, and environmental factors.

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Alexandra Fedorova

Journalist, author of articles on construction and repair. I will help you understand the complex issues related to the choice and installation of the roof.

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