A commercial roof is a complex system made up of multiple components that work together to protect your building from the elements. When it comes to maintaining your commercial property, the roof plays a crucial role in safeguarding the building’s structure, its contents, and the people inside. Whether you own a building or manage a facility, understanding the basic terms associated with commercial roofing can help you make informed decisions regarding repairs, maintenance, or new installations.
Let’s break down the parts of a commercial roof and go over some of the key terms every property owner or manager should know.
Roof Deck
The roof deck is the foundation of the roof structure, and it provides support for the entire system. It can be made of various materials, including wood, steel, concrete, or gypsum, depending on the type of building and your local regulations. The deck is usually flat or slightly sloped, and its main job is to support the weight of the roofing materials, insulation, and any external forces, such as snow or wind.
Terms related to the roof deck:
- Substrate: The layer of material on which the roofing system is applied. It could be plywood, concrete, or other materials.
- Sheathing: Another term for the roof deck, often referring to the layer of material that covers the rafters and provides a surface for the roof covering.
Roofing Membrane
A roofing membrane is a waterproof layer that forms the outermost part of the roof system. It is typically made from materials such as TPO, EPDM, PVC, or modified bitumen. The membrane protects the underlying layers from water damage and extreme temperatures.
Types of roofing membranes:
- Single-Ply Membranes: These include materials like TPO, EPDM, and PVC, which are installed in large sheets to cover the entire roof.
- Built-Up Roofing (BUR): This consists of multiple layers of bitumen and reinforcing fabrics, creating a sturdy, water-resistant barrier.
- Modified Bitumen: A combination of asphalt and rubber or plastic, this membrane is commonly used for its durability and ease of installation.
Insulation
Roof insulation is crucial for regulating the temperature inside a commercial building. It helps reduce energy consumption by reducing heat loss in the winter and heat gain during the summer. Insulation can be installed directly on top of the roof deck, beneath the roofing membrane, or as part of a composite system.
Types of insulation used in commercial roofs:
- Polyisocyanurate (ISO): Known for its high thermal resistance, this type of insulation is commonly used in commercial roofs.
- Extruded Polystyrene (XPS): Offers durability and moisture resistance, making it a popular choice for flat roofs.
- Expanded Polystyrene (EPS): This cost-effective option provides excellent thermal properties and is often used for roofs with a lower budget.
Flashing
Flashing is a thin material, often made of metal, used to seal joints and prevent water from entering vulnerable areas of the roof. Flashing is applied around roof penetrations such as vents, chimneys, skylights, along seams, and at the edges of the roof. It acts as a barrier that directs water away from critical areas, minimizing the risk of leaks.
Common types of flashing:
- Counter Flashing: Installed on top of base flashing to prevent water from seeping underneath.
- Base Flashing: Installed at the point where the roof meets vertical surfaces, like walls or chimneys, to direct water away from seams.
Drains and Scuppers
Proper drainage is essential to prevent standing water from accumulating on a commercial roof, especially those that are flat or low-slope. Standing water can lead to leaks, structural damage, and the deterioration of roofing materials. Roof drains and scuppers are used to channel water off the roof and into the building’s drainage system.
- Roof Drains: These are usually installed in low-lying areas of the roof to allow water to flow down pipes and into the building’s stormwater system.
- Scuppers: Openings in the parapet walls that allow water to drain off the roof. They are typically used in combination with downspouts.
Parapet Walls
A parapet is a low wall that extends above the edge of a roof. It’s typically used to provide safety, prevent wind uplift, and help with drainage. Parapet walls are common on flat or low-slope roofs and can be constructed from materials such as masonry or metal.
Purposes of parapet walls:
- Aesthetic Appeal: Parapets can contribute to the architectural design of a commercial building.
- Wind Protection: The wall helps mitigate wind uplift, preventing the roofing membrane from being lifted off.
- Fire Safety: They can also act as a fire barrier, especially in densely populated areas.
Vents and Roof Penetrations
Vents and other roof penetrations, including HVAC units, skylights, and plumbing pipes, are common features of commercial roofs. These penetrations need to be properly sealed and flashed to prevent water infiltration. They also play a vital role in ventilation, allowing for airflow in and out of the building.
Types of vents include:
- Plumbing Vents: Allow gases and odors to escape from the building.
- Rooftop Units: HVAC units or other mechanical equipment that are installed on the roof.
- Skylights: Provide natural light to the building below, but also require proper sealing to avoid leaks.
Roof Slope
The slope, or pitch, of the roof plays a significant role in its ability to drain water. Roofs can be classified as flat, low-slope, or steep-slope. Each type requires specific materials and installation methods to ensure optimal performance.
- Flat Roof: These roofs are almost completely level with only a slight slope to allow water to drain. They are common in commercial buildings.
- Low-Slope Roof: Slightly steeper than flat roofs, these roofs generally have a slope of 4:12 or less. This ratio is calculated based on the number of inches a roof’s elevation rises for every 12 inches of horizontal length.
- Steep-Slope Roof: These roofs are often found on residential buildings but can be present in commercial properties, especially for specific architectural styles. They typically have slopes greater than 4:12.
Roof Coatings
Roof coatings are an additional layer applied to the surface of a commercial roof to extend its lifespan. Coatings enhance the waterproofing of your roof and improve its energy efficiency. They can also help reduce the roof’s surface temperature by reflecting sunlight, ultimately reducing cooling costs for the building.
Types of roof coatings:
- Acrylic Coatings: Highly reflective and UV resistant, these coatings help improve energy efficiency.
- Silicone Coatings: Known for their durability and water resistance, silicone coatings are often used in areas with heavy rainfall or high humidity.
A solid understanding of your commercial roof will help ensure that you are armed with the knowledge to keep your property secure and protected for years to come.
If you have questions about your commercial roof, give our experts a call!
Recent Comments