A Commercial Roof Guide – Flat Roofs for Building Owners and Property Managers

Posted on December 2, 2021 by baker-admin

A Flat Roof Guide for Commercial Building Owners and Property Managers

When you are a commercial building owner or a property manager, being committed to a budget is essential to making a profit. One of the most critical components of your building is the roof system.

Budgeting for preventative maintenance, repairs, and eventual replacement of your roof will help you maintain a successful budget.

Preventative Maintenance Program

A Preventive Maintenance Program (PMP) will ensure your roof is in its best condition for its entire lifespan. Implementing a PMP will keep your roof clean and free of harmful debris, ensure that it is properly sealed and that minor repairs are completed before they can become significant issues.

Additionally, a PMP will provide you with a timeline of the life of your roof, allowing you to plan and budget for its replacement. The roofing company providing you with the PMP can help you save money by limiting the number of significant repairs and water damage that results from roof issues. They will also tell you when the repairs will cost you more in the coming years than a replacement would cost.


Flat roofs are designed so that minor repairs can be performed at a minimum cost. Waterproof membranes get small pinhole punctures, tears, and perforated seams. All of these types of repairs are quickly repaired. However, repairs will be needed more frequently as the membrane ages, and the cost will also increase. At this time, it is wise to consider a new roof covering.


Flat Roof Systems

Flat roof systems are actually all low-slope roofs that have a roof pitch of 4/12 or less. That is to say that the roof slopes 4 inches for every one linear foot or less.


BUR Roof System

Built-up roof systems are roofs primarily comprised of a three-piece system, bitumen, ply sheets, and a top layer. Insulation board can also be incorporated for a fourth component of the BUR system.

If an insulation board is used, it will be installed first and then layered with bitumen, which can either be cold or hot-applied and ply sheets. After several layers have been applied, a top layer of a specialized ply sheet or a stone or gravel ballast finishes it off.

BUR roof systems have been around for many years and are one of the oldest flat roof systems.

TPOTPO seams hot air welded

TPO is thermoplastic polyolefin, a single-ply waterproof membrane that began being installed in the US on flat roofs in the 1990s. An insulation board is installed before the TPO membrane, and TPO can be installed fully adhered with an adhesive or installed mechanically with plates and screws, and then the seams are hot-air welded.

TPO waterproof membranes can last up to 30 years if well maintained with a proper preventative maintenance program, but other components will fail. Seams will need to be re-welded, and flashings will need to be re-sealed.


EDPM (ethylene propylene diene monomer) is a synthetic rubber single-ply waterproof membrane. While similar to TPO is has a much different chemical makeup, and it is a durable, tear-resistant material. EDPM is very versatile can be used in various roofing situations, including under solar panels, green roofs, and can even be used in water features as a liner.

EDPM does have its issues. As EDPM ages, it may be susceptible to shrinkage, cracking, and eventual tears. Additionally, it does not have the best heat reflection as some other roof coverings like TPO.


Torch down modified roofing membraneModified Bitumen

Modified bitumen is a roofing system is comprised of two components, base sheets, and cap sheets. The roofing material is applied in two ways either torch down or self-adhered. The most common and acceptable application for commercial flat roofs is applied with heat, and a roofing torch is used to heat the bitumen that is attached to the ply material. The ply is rolled out as it is being heated, and it seals to the roof deck. Depending on the roof specs, Multiple base layers can be installed on top of each other, but only one base sheet is the most common system.

A cap sheet is applied the same way as the base sheets; the difference is that the cap sheet is granulated on top to add to the protection of the ply. Cap sheets come in several different colors, some of which are considered cool roofs, which are better with heat transmissivity.

Self-adhered base and cap sheets are precisely as they sound. They have adhesive on the back and stick down to the roof deck. Self-adhered sheets are more often used on small projects or in residential roof systems.

Liquid Applied Roof Membrane

Liquid applied roof membranes are waterproof roof coverings that are sprayed or rolled on the entire roof. Liquid applied roof membranes are one continuous membrane, so there are no seams that can leak or come unsealed. The membrane can be rolled on at different rates that will affect the thickness and protection it will provide.

Liquid applied roofing membranes are available in different chemical makeups. Acrylic, urethane, silicone, and fluoropolymers are all standard liquid membranes. Each type has its benefits and features that make them good choices.

Metal RoofStanding Seam metal roof

Metal roofing is an attractive choice to make a statement on flat roofs. The seams on the standing seam roof need to be mechanically fastened, which means that a machine bends the two panels together and crimps them together. When metal roofing, like a standing seam metal roof, is installed on a flat roof, a specialized ice and water barrier must be used to ensure a tight water seal. We always suggest using this specialized high-temperature ice and water barrier in place of synthetic underlayment. Ice and water barrier is a thick self-adhered membrane that was designed to be used at the eaves of the roofs to prevent water damming in northern climates. It is important to use a high-temperature type of ice and water to prevent it from melting, running, and causing streaking damage down the side of the structure.

Flat Roof Accessories

The benefits of flat roofs are their ability to hold the building’s accessories like HVAC units, rooftop patios, green spaces, solar panels, and even extra storage. The roof you choose will determine how the rooftop can be used. Obviously, a roof system like standing seam metal roofs will not allow you to walk on it or use it to provide extra storage, patios, or green spaces. Waterproof membranes are the best option to allow you maximum flexibility with your rooftop, provided you use the correct materials to protect the membrane.

Solar panels

Flat roofs make excellent places to add solar panels to reduce utility costs and allow your building to be more eco-friendly. A flat roof will allow the solar installers to position the panels at the most optimal angle to collect the most energy possible, unlike steep slope roofs.

Rooftop Patio

A rooftop patio can add value to your building and make it more desirable to potential tenets. Many considerations are needed before choosing to build a rooftop patio, including roof access, a beautiful view, and protective retaining walls.

Green Spaces

Much like a rooftop patio, green spaces can allow a great escape from stressful work and be an inviting place for tenants. These green spaces can be flower gardens or even small produce gardens.

Walk Pads

Installing walk pads is important on any waterproof membrane to protect the roof and maximize its lifespan. These pads are specialized pads laid strategically to allow maintenance workers to navigate the roof without walking all over the membrane and causing premature wear.

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