What Roofing Material is Best for a Flat Roof?

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What Roofing Material is Best for a Flat Roof?

At City2Surf Roofing, we’ve been in the roofing business for many years, and our experienced roofing contractors have managed roofing jobs for a variety of buildings. Most of the roofs we’ve encountered are pitched roofs, and some are quite steep. But a flat roof requires a different approach when it comes to proper roof installation. What kind of roofing materials are best for a flat roof? We’ll explore the options below.

What types of roofing materials are best used for a flat roof?

Every roofing system has its own unique needs, and each material has its pros and cons. When it comes to flat roofs though, single ply roofing materials are what roofing contractors will use to repair or install a new flat roof.

  • Ethylene Propylene Diene Monomer (EPDM Rubber)
  • TPO Vinyl
  • Built-up Roofs (BUR)
  • Modified Bitumen Torch Down

The most popular of these three choices are EPDM Rubber and Modified Bitumen roofing materials.

Modified bitumen comes in two different types of roofing materials, torch down and peel and stick. Peel and stick is a light coloured, mineral surface that is excellent for reflecting heat and cutting down on energy usage and its associated costs. Cost-wise, peel and stick modified bitumen falls within the mid-price range. Torch down modified bitumen requires heat welding to install and is recommended for buildings that aren’t occupied.

TPO vinyl is an incredibly new material and offers significant energy efficiency. But, finding a contractor experienced with installing it can be a challenge. It’s also one of the most expensive options.

BUR roofs are one of the oldest types of flat roofing materials available and consist of hot tar and gravel. These types of roofs are fire resistant and attractive, and one of the most affordable flat roofing materials. But, tar and gravel is a heavy material, and messy and complicated to install. It can clog gutters and isn’t recommended for occupied buildings, either. If you have a window or balcony that overlooks a flat roof, then a hot tar and gravel BUR roof is an attractive and affordable option for your property.

Pooling water is a huge concern with flat roofs. But when it comes to knowing what type of roofing material to install on a flat roof, sunlight is going to be a critical factor in your decision.

The biggest issue with flat roofing materials is that a flat roof will receive a lot more direct sunlight during its lifetime than a pitched roof. Direct sunlight, or ultraviolet lights, will break down the roofing materials, and also create more heat that leads to faster disintegration, too. The only type of roofing material that is UV resistant are stone and ceramic roofing materials. Modified bitumen has ceramic granules in the membrane, whereas EPDM Rubber roof membrane does not.

What are the pros and cons of EPDM Rubber and Modified Bitumen Torch Down?

  • EPDM Rubber is .3175 centimeters thick
  • The material is not UV resistant, and can’t be coated against UV light
  • Can’t withstand heavy foot traffic
  • The seams are glued together, meaning it is not very heat resistant
  • Is a good roofing choice for people who live in temperate climates
  • More expensive than modified bitumen or BUR materials

The biggest con with EPDM Rubber roofing material is that the seams used to connect the single-ply rubber membrane are glued together with an adhesive. This adhesive is contact cement, and the manufacturer has recalled it many times over the last 40 years. Part of the issue with flat roofing materials lays in the roof’s construction, itself. A flat roof is going to get a lot of direct sunlight and therefore, heat. So, the glue or adhesive in a rubber roof membrane will quickly break down, significantly shortening the roof’s lifespan. The good news is, tears in an EPDM Rubber roof are relatively easy and affordable to fix.

EPDM Rubber is also a thin material that can be damaged easily from foot traffic or falling debris. If you have an air conditioner or another critical component of your home that needs work and contractors must use the flat roof to gain access to it, you risk compromising the roof from the increased foot traffic. Although our City2Surf roofing contractors know how to walk on a flat roof the correct way, most other contractors and workers do not.

Without any maintaining problems, a flat roof coated in single ply EPDM Rubber will last between 10 and 15 years. Also, EPDM Rubber was never intended to be applied to a commercial building’s flat roof. But over the last several years, EPDM Rubber use on commercial flat roofs has soared. Even though EPDM Rubber has been around for over 50 years, there is no sustainable way to avoid the substantial breakage and short lifespan of an EPDM roof, other than adding a protective ceramic coating to it.

Fortunately, modified bitumen is a much more durable option for owners of flat roofs.

  • Modified bitumen is more than one centimeter thick.
  • Ceramic granules are embedded into the material to protect against harmful UV light.
  • Foot traffic and maintenance will not damage the roof.
  • Requires little preparation before it can be installed.
  • Can be painted.
  • The seams are heat welded and won’t separate.
  • The material falls within the mid-priced range.
  • It’s a newer material, so it may be difficult to find a contractor who is experienced working with it.

Why is modified bitumen a good choice of roofing material for a flat roof?

The main issue with EPDM Rubber is the glue holding the seams together. With modified bitumen, the seams can be heat welded with torch down modified bitumen, meaning the material won’t break down as quickly from heat and sunlight. Because modified bitumen is a thicker, and sturdier roofing material, modified bitumen is also much easier to maintain or repair that EPDM Rubber.

Modified bitumen can withstand higher levels of foot traffic. When it comes to flat roofing systems, they are usually the main access point for many critical components of the home, such as air conditioning units. Flat roofs also collect snow, and it’s crucial to shovel the roof when this happens. With modified bitumen, the roof won’t sustain any damage from regular foot traffic.

Compared to other flat roofing systems, modified bitumen will last longer and require less maintenance.

Over time, roof coatings and roofing system rubber membranes will shrink from the freeze and thaw cycle, or heat, or simply from age. This causes the roofing materials to pull away from the wall and the flashing, giving water and pests an access point into the underlying roof structure. With modified bitumen, shrinking is minimal to non-existent, even without routine maintenance.

A modified bitumen roof will last for 20 years. This roofing material is an excellent choice for commercial and residential buildings alike. When it comes to cost, a modified bitumen roof is more economical than an EPDM Rubber roof.

EPDM Rubber roofs require a significant amount of preparation before they can be installed. With modified bitumen, there is minimal upfront cleaning and preparation. Because modified bitumen is a newer flat roof material, many contractors are not familiar with how to install it. Here at City2Surf, we make it a priority to keep up-to-date on the latest roofing materials and installation techniques. We’re familiar with modified bitumen installation and upkeep.

Why would someone install an EPDM Rubber roof over a modified bitumen roof?

For buildings in temperate climates that do not see extreme temperature swings, an EPDM Rubber roof is a decent choice. If the flat part of your roof is shaded, an EPDM Rubber roof can last longer since it will avoid harmful UV light.

But when it comes to Australian weather, temperatures can be extreme. EPDM rubber roofs are subject to shrinkage, and so a modified bitumen roofing system is a less risky choice of roofing material. While it can be challenging to find a contractor who is experienced at installing a modified bitumen roof, City2Surf can install modified bitumen roofs for property owners in the Sydney area.

How do you know when a flat roof needs to be replaced?

There are many signs that a flat roof is about to take its last breaths. Flat roofs are more susceptible to leaks and other malfunctions than pitched roofs. One of the most significant issues homeowners experience with a flat roof is pooling water. If you have a pool of water on your flat roof that stays put for 48 hours or more, then the structural integrity of the roof is compromised, and it will need to be replaced soon. Failing to install a new rubber membrane can cause water to get into the walls of the home and cause huge issues for you, most notably mould.

Signs you need to replace a flat roof:

Pooling Water

While some water pooling is typical for a flat roof, if you have water that remains on the roof for at least 48 hours, the roof needs replacing. An experienced roof contractor can install foam pieces or other slippers below the new rubber roof membrane to give the new roof a slight pitch, preventing excessive water pooling and extending the lifespan of the roof.

Tears in the rubber membrane or the membrane have pulled apart at the seams.

Flat roofs require pieces of single-ply material to either be glued or welded together. If you notice tears or shrinkage, the roof needs to be replaced. A slight tear can be repaired, but significant rips or holes mean water or pests will find their way under the roof.

If your original roofing material is made out of hot tar or gravel, it can be difficult to repair. If you notice any of the above signs, then it’s best to contact an experienced roofing contractor to fix the roof.

How can a property owner decide to repair or replace a flat roof with a new roofing material?

The roof is one of the most significant components of your home, and it’s a considerable investment. A new roof will keep water and pests out, and also improve the resale value and curb appeal of your home. For some property owners, it might be beneficial to repair the flat roof instead of replacing it. If the material that your roof is made out of is relatively new, and if tears or other damage are minimal, just repairing the roof might be a good choice.

But, if the roof has reached the end of its service life, and if repair costs would be more than 20% of the price of a new roof, it’s better to take the plunge and get a new flat roof installed. A new roof will give you peace of mind knowing that it will last for 15 to 20 years at least. Also, a new roof will improve the home’s curb appeal and resale value. If you’re looking to put the property up for market soon, replacing the roof can inspire confidence in potential buyers and help you recoup your losses on the initial investment.

How can City2Surf help you with your flat roof repair or installation?

When you contact us for a roof installation quote, our experienced contractors will go to your property and inspect the roof. We’ll take into account the materials already in place and the extent of the damage. We’ll be able to give you a detailed and accurate quote based on your budget, and what types of flat roofing materials would be the most advantageous for you to have installed. If you’re ready to have your flat roof repaired or replaced, contact City2Surf for your free, no-obligation quote today.

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