Pros And Cons Of Flat Roofing For Commercial Properties

While a popular choice for commercial buildings, flat roofing isn’t always the right choice for every business.

Use our helpful pros and cons guide to navigate your options, and decide whether a flat roof is the way to go for your commercial property.

No fluff, just the facts!

What is commercial flat roofing?

Commercial flat roofing refers to roofing systems with a low slope (under 10 degrees) used on commercial and industrial properties. It’s pretty common in warehouses, storage facilities, office buildings, factories and blocks of flats.

Advantages of flat roofing for commercial buildings

Let’s start with the pros. If you’re considering an industrial flat roof, these are some of the benefits you can expect.

Flat roofs cost less (materials and labour)

Flat roofs are a go-to choice for many commercial buildings because they offer big savings on both materials and installation.

Unlike sloped roofs, they don’t need as much structural support like trusses or angled panels, which helps keep hefty construction costs down.

On top of that, their straightforward design makes installation quicker and more affordable, cutting down on labour expenses.

Another often overlooked saving is that you can easily install solar panels on a flat roof, saving you money on the utility bills for years to come.

Easier installation & maintenance

Time is money, and if the roof you’ve installed goes up quickly and doesn’t require much maintenance, you’ve made a big saving.

The simple design of industrial flat roofing speeds up the installation process (as little as a few days, depending on the size of the roof) and makes routine maintenance, inspections and repairs much simpler.

Their design also makes it easy to add extra gutters or drainage points if needed, ensuring water is managed effectively and your building stays protected.

Space, the final frontier

A flat roof is a big space saver, no doubt about it. Flat roofing is ideal for fitting heating, ventilation, air conditioning (HVAC) units, solar panels, green roofs, or even rooftop patios, maximising otherwise unused space.

Flat roofing can get you more usable square footage inside too, especially if you’ve got a warehouse or retail unit with an open layout.

Energy efficiency savings

Another win for the wallet. We’ve talked about solar panels, but flat roofs can also provide good insulation and open up your options for reflective coatings to reduce heat absorption, promoting cooler temperatures in the summer months.

Flat roofs also tend to use what’s known as ‘rigid insulation’, providing a thermal barrier with continuous coverage and no gaps or weak spots. Super energy-efficient.

Easy to add rooflights

It’s easy to add rooflights to flat roofs, meaning you can benefit from all the advantages of rooflights and skylights.

These include:

Increasing the amount of light in a room
Improving air quality and ventilation
Increasing home value
Design benefits
Greater temperature control
Privacy
Making your room appear more spacious
Improving energy efficiency
Mental health benefits

Learn more about the benefits of rooflights.

We offer a range of rooflights and skylights, but our most popular feature for flat roofs is the flat roof skylight window. Get yours at a fantastic price today.

Disadvantages of flat roofing for commercial buildings

Where there are pros, there are usually cons. Flat roofing isn’t the perfect solution for every commercial property, so here are some of the most common disadvantages:

Water drainage

One of the main challenges with flat roofs is managing water drainage. Due to the minimal slope, rainwater and melted snow can pool on the roof, which can cause leaks, water damage, or even structural issues if not properly addressed.

While modern flat roofs are designed with drainage systems, these systems need regular maintenance and aren’t quite as effective as those on pitched roofs. It can cost a lot to repair or replace them, too.

Shorter lifespan

In our experience, flat roofs tend to have a shorter lifespan than their pitched counterparts. This is mainly due to the stress of standing water and more exposure to the elements, which can cause materials to deteriorate faster.

A traditional sloped roof (with its natural drainage) generally lasts longer and may require fewer repairs. Depending on the material you use for a flat roof, you might face replacement costs earlier than you would with a pitched roof.

Curb appeal

While flat roofs are super functional, they aren’t always the most aesthetically pleasing choice. In some commercial settings, a flat roof might look a bit out of place, especially in areas with lots of old buildings or historic architecture.

Businesses looking to improve ‘curb appeal’ find a flat roof less than inspiring. While there are options for creating a more attractive rooftop (like green roofs or a rooftop garden), these come with additional costs and upkeep. Not a big deal, but one to bear in mind.

Vulnerability to weather

In the UK, we’re no strangers to bad weather, and flat roofs can struggle more in extreme conditions like heavy snow, strong winds, or intense heat (remember the 40-degree July in 2022?). Flat roofs can overheat, leading to faster material breakdown.

In colder spells, snow and ice buildup can lead to leaks or even cause the roof to collapse if the weight isn’t properly distributed.

In conclusion, while flat roofing offers several advantages in terms of cost, space, and energy efficiency, it’s important to weigh up the potential drawbacks, too. With proper planning and maintenance, many of these cons can be easily managed and mitigated.

FAQs

Here are some of the more common questions we hear when talking to customers about flat roofing options.

Which flat roof material is best for commercial properties?

For commercial flat roofs in the UK, it tends to be PVC (Polyvinyl Chloride) and EPDM (a rubber-like material called Ethylene Propylene Diene Monomer) that get used most often because they’re durable, long-lasting, and easy to install.

PVC is known for its resistance to fire, while EPDM is known for its low cost, flexibility and ability to withstand different weather conditions.

Do flat roofs need ventilation?

Yes, most of the time. Commercial flat roofing in the UK typically requires ventilation to prevent moisture buildup, condensation, and potential long-term damage. Building regulations will usually insist on you ventilating a flat roof.

Depending on the type of roof you install, you might need continuous ventilation gaps (a 25mm gap on two sides of the roof), airflow paths (between the vents and the roof void) or ventilators installed in the eaves.

What happens to rain on a flat roof?

Because of the slight slope, rainwater is diverted to the guttering in order to control its descent into the drains below. Guttering has to be sturdy, and tends to be a particular size to withstand adverse weather conditions.

Pros and Cons of Flat Roofing for Commercial Properties