Roofing 101

Types of Flat Roofs and What to Expect

commercial roofing

It can be a challenge to select the right materials for your Flat roof; whether it is a residential or commercial building. More importantly, when it comes to your business, the last thing you need is for an issue to interfere, like a roof leak. In this blog post we will cover what to look out for when it comes to flat roofs, the different types of preferred materials you can choose from, and the pros and cons of each material.

Do all roofing companies provide the same level of expertise? 

When you think of a roofing company you may think of a company that can repair or install any type of roof. Well, the truth is that some companies may be better at a specific type of roofing than others. For instance, they could specialize in shingles and metal roofs but have little experience with flat roofs. So you want to hire an expert who specializes in this particular method and are experts in all aspects of commercial and residential roofing, including installation, maintenance, and repair. For instance, here at Roofing101, we use the best products from top-of-the-line manufacturers to ensure that your commercial and residential property gets the highest quality roof possible. We also help you select a roofing or re-roofing treatment that suits your needs and your budget. Ultimately, you want a company that can give you the highest quality application technique, quality control, and attention to detail.

Why should you care what type of flat roof you install? 

Well, when it comes to flat roofs, there are many different materials and methods of

installation. Just like most things in life, if it is not well done, it will not last. That is what you will want to hire a company that has all the qualities mentioned above and who works in accordance with building codes. At Roofing101 we believe in creating the best experience for you and your home.

What are the three types of flat roofs?

1. TPO (Thermoplastic Polyolefin)

2. EPDM (Ethylene Propylene Diene Monomer)

3. Modified Bitumen Roof 

TPO (Thermoplastic Polyolefin) has been around for 20 years and it’s one of the youngest and fastest-growing commercial roofing systems on the market. The material is made up of a single-layer membrane of synthetics and reinforcing scrim. Because this material is white, it reflects the solar radiation ultraviolet light. It has a protective system that deflects the sun which helps to reduce the demand for air conditioning in hot weather, which leads to saving you money.

How is TPO installed and what is the cost? 

TPO comes in 45 or 60 thousandths of an inch in thickness. It is a little more complicated to install as it requires more equipment and good application technique. TPO is hot-air welded together with a machine that runs down the seam and heats the membrane to a playable surface that adheres to itself. This installation method seems to be more efficient than EPDM because it’s much less prone to separation due to the way it’s installed because it is heat pressed as opposed to seamed tape or glue.TPO will usually cost between $5 and $9 per square foot. If installed properly and maintained well, a TPO roof should last up to 15-20 years.

The downside to TPO is that it is a newer product so it hasn’t been tested as much as some other materials. It also expands and contracts due to the weather so it will be affected by this and if you do not hire the right contractors there can be issues such as the material being improperly welded and may come loose, causing issues such as leaks and premature damage.

EPDM Roofing (Ethylene Propylene Diene Monomer) is an older method that has been around since the 1960s. EPDM is also referred to as “rubber roofing,” because it’s a single-ply membrane material that is flexible like a synthetic rubber compound. EPDM roofing has a dark membrane, therefore, it absorbs the heat, unlike TPO that deflects it.

How is EPDM installed and what is the cost? 

EPDM has different thicknesses that come in 45, 60, or 90 thousandths of an inch. The industry standard is 60 thousandths of an inch for thickness which is about the size of a  quarter coin. With EPDM, the seam is rolled together with a chemical bond. This method is cheaper to install because it’s easier and requires less application technique. The material is lighter than others and it’s more convenient because it is sold in wide rolls. If you decide to go with an EPDM roof installation, you should expect to pay somewhere between $4 to $8 per square foot. Generally, experts know that a well-done installation provides a property owner with 25 to 30 years, but it is said that it can even last up to 50 yrs. The lifespan also depends on the thickness of the material. Additionally, regular maintenance and inspections that detect any issues or signs of trouble can extend the life span of the roof.

The downfall to EPDM roofs is that the ultraviolet rays of the sun can degrade the adhesive glue used on the seams which can cause premature separation. Also, the membrane being black attracts ultraviolet light, which affects its lifespan because it expands and contracts due to the weather. Protective mats are also needed during the installation as this material can puncture easily, so this is another reason to ensure you hire a certified professional!

Modified Bitumen roofing began in Europe in the 1960s and became popular in the United States around the 1970s. This is an asphalt-based material that is designed to withstand harsh exposure to extreme environmental elements. However, the popularity of more modern single-membrane systems (EPDM & TPO) has reduced the demand for modified bitumen roofing.


How is Modified Bitumen installed and what is the cost? 

A Modified Bitumen roof generally consists of two layers: a base sheet and a cap sheet. The cap sheet is similar to an ice-and-water shield with a thickness of about 40-80 mils in thickness, making self-adhered systems less susceptible to punctures from foot traffic. This material is layered with a gradual ceramic layer that protects it from ultraviolet degradation and is puncture resistant. The base sheet is often self-adhered while the cap sheet is torched down to be fused together to prevent separation. It is designed to be flexible, which helps the longevity of the material, especially in extremely hot or cold weather conditions. It is easy to install and you can layer it on top of old materials. The cost for a Modified Bitumen roof is $4-$6 per square foot. Modified Bitumen roofing has the shortest lifespan of 15-20 years. But since it’s a low-maintenance roofing system, it can last even longer with just basic care and maintenance.


The breakdown of flat roof materials: 



• Protects against UV light

• Lower electric bill

• Higher resistance to punctures

• Lifespan 15-20 years



• A newer product on the market

• It expands and contracts due to weather

• there can be issues such as the material being improperly welded and

may come loose, causing all sorts of issues such as leaks and premature





• Cheaper than TPO

• Easy installation

• Leaks are easy to patch

• Longest lifespan of 25-30 years



• The standard black material absorbs heat

• It’s also more vulnerable to punctures

• Adhesive glue can come loose

Modified Bitumen:



• Easy to install

• Its price is in the middle of the pack.

• High resistance to puncture

• Flexible material

• Class A fire-resistant

• Easy to repair tears or holes in the system



• The lifespan of 15 – 20 years even less if it gets damaged.

• When Modified Bitumen is applied using the heated torch method it releases harmful fumes. After installation, the odor of the new roof may last for a few days.

What do you need to take into consideration when it comes to choosing the right material for your home?

It heavily depends on the area and climate you live in because each material will do better or worse depending on its environment. The other thing you have to take into consideration is your building code, some codes may require specific materials which would limit and restrict your options. There are also a lot of factors that come into the pricing of a new roof. It will vary depending on the grade of the material you choose, whether there was removal of existing roofing material, the extent of the damage, the size of the roof, and so forth.

Another important add-on to your flat roof is that you may want to look into is SPF (Spray Polyurethane Foam). This is a popular roofing option for flat and low-slope roofs to add extra protection. SPF is a spray-applied material that is made by mixing chemicals to create foam. This is applied with spray equipment providing a roof covering that can go over an existing roof or over new construction. SPF is widely used because it insulates the building, seals cracks, and gaps,

making the building more energy-efficient and provides a moisture barrier.The foam material is designed to expand and contract in accordance with outside temperatures and therefore reduces the likelihood of cracks and splitting. Once an SPF roof is installed, it requires minimal maintenance and depending on the thickness of the coating it can last over 10-20+ years. It is even said it can last up to 50 years. The application of the spray foam is a process that needs to be done correctly from the beginning. The contractor needs to be precise with the application and have a solid understanding of the chemicals they are using. It doesn’t take a large crew to install an SPF roofing system, but it requires a high degree of technical knowledge and experience.