Flat roofing is becoming an increasingly popular alternative to traditional, sloped roofing. There are many reasons for this, including cost, planning permission issues, utilisation, and more. Flat roofs work well for extensions and outbuildings, but also for larger commercial buildings.
But what exactly is a flat roof? What goes into constructing them, how are they maintained, and why are they popular? Is flat roofing the best choice for your property? In this article, we aim to answer these questions and more by breaking down everything you need to know about flat roofing.
What is Flat Roofing?
Flat roofing is roofing that appears to be a continuous, level surface. It does not use a system of overlapping roof shingles like a pitched (sloped) roof.
Usually, especially in wetter countries, flat roofs will have a very slight slope so that rain can run off the edge of the building and/or be drained through a guttering system. This means that flat roofs are able to avoid water pooling and resulting damage.
Flat roofs tend to be made using extremely weather-resistant and watertight materials, such as bitumen, rubber, or metal. However, snow and other debris build-up can pose more of an issue for a flat roof than a pitched roof.
On the other hand, the advantages of flat roofing are numerous.
The Advantages of Flat Roofing
The main reason flat roofs are popular is their cost. At both the construction and maintenance stages, flat roofs are cheaper and easier than sloped roofs. Flat roofs require less space and therefore fewer materials for construction. They are also much more accessible, meaning any necessary repairs are easier to assess and carry out.
The savings don’t stop there, however. The weather-resistant materials used for a flat roof are also thermally efficient. They help retain heat during the colder months or keep the building cool during warmer ones. Furthermore, the additional space acquired with a flat roof can be put to use. Whether it’s used to store units that would otherwise take up space inside a building or for an exterior feature such as solar panels, there’s potential for an improved economy with a flat roof. Alternatively, many choose to turn their flat roofs into usable spaces or gardens! Flat roofs can be made as green roofs.
Flat Roof Construction: Warm Flat Roofs vs. Cold Flat Roofs
The main variations in flat roof construction are known as warm and cold flat roofing. The difference between these is, in simple terms, whether the roofing insulation goes above or below/within the roof deck, the roof structure below the covering and surface layer.
With a warm flat roof, the insulation goes above the roof deck and the roof deck itself is therefore better insulated. This means it will incur less damage due to thermal changes or accumulation of moisture. On the other hand, a cold roof deck requires ventilating in order to avoid condensation - this can be tricky and is not always 100% effective.
While it is true that cold flat roofs are becoming far less popular, they do offer some key advantages. One such advantage is that the roof surface is laid directly over a structurally sound roof deck. If you intend to use your flat roof as a social space, storage space, or other useable space, a warm roof is not usually advised. This is because the roof covering material sits directly on top of the insulation and, given that the insulation won’t be completely rigid, may get damaged if pressure is applied. A warm flat roof that is regularly in use is likely to suffer wear and tear much sooner than a cold roof that sees roughly the same usage.
Types of Flat Roof Coverings
Bitumen/Built-Up Felt
The traditional covering for flat roofs can have a bad reputation due to old-fashioned felt roofs suffering wear and tear and leakage over time. Additionally, before it was recognised as dangerous, asbestos may have been used within these roofs in the past. However, felt roof coverings have come a long way and are now far more durable than their predecessors - and, of course, they are completely asbestos-free!
Bitumen or built-up felt is one of the most cost-effective roofing materials and is a tried and tested waterproof cover for flat roofs. It is harder to repair yourself than other roof covering materials and is also less environmentally friendly, but built-up felt remains one of the most popular flat roof coverings today.
Single-Ply Membrane
Single-ply membranes are synthetic polymer-based roofing materials, most often supplied in rolls. They are light, versatile, affordable and relatively quick and easy to install. They are also more environmentally friendly and easier to repair than felt roofing. So, although they cost more than felt, they may have reduced costs over time.
The five main types of single-ply roofing membranes are:
PVC (Poly Vinyl Chloride)
EPDM (Ethylene Propylene Diene Monomer) AKA Rubber roofing
TPO (Thermoplastic Polyolefin)
TPE, (Thermoplastic Polyolefin Elastomer) and
PIB (Polyiso Butylene)
Discuss the many roof covering options with your flat roofing contractor. Some are more eco-friendly than others, while others may be more durable, customisable, versatile, or affordable. The guarantee period of each roofing material will differ, so it’s worth considering all the factors at play before choosing which material is right for your roof. The one that is initially the cheapest and most convenient may not always be in the long run.
Common Flat Roof Repair and Maintenance Issues
In order to avoid roof restoration costs sooner than you’d like, stay on top of flat roof repairs and maintenance. Following are some common flat roof issues to be aware of and keep an eye on, so you can better extend the lifespan of your flat roof.
Leaking and Ponding
As with all roofs, one of the major concerns with regard to flat roofs is leakage. Over time, any roof can become weather damaged to the point of sustaining a leak. A flat roof can be particularly vulnerable due to ponding, which is when a flat roof becomes overwhelmed by rain, snow, or ice and water pools across the roof’s surface.
Despite their engineered sloping and drainage, flat roofs can suffer from ponding after particularly heavy weather or gradually over time. If pools of water stand for 48 hours after the adverse weather has stopped, it can begin to degrade the roofing material. Unattended, this can eventually wear through and cause serious problems.
It’s important to carry out regular maintenance checkups with a flat roof, keeping a watchful eye out for ponding in particular. Annual maintenance surveys are advised, as is checking on your flat roof 48 hours after heavy rain or snow to check for ponding. Leaks can obviously cause serious issues and further damage, so it’s worth maintaining a flat roof well to prevent them. During a survey, check for any signs of moisture penetrating the covering wherever possible.
Exposed Layers
As with any roof, your flat roof will be exposed to all sorts of weather conditions. From heavy rains and high winds to hot days or freezing nights. It’s inevitable a roof will sustain wear and tear over time due to the elements. This is why every roof has a life expectancy. Stay on top of any weather damage, such as cracking or blistering, with regular maintenance checks of the roof. Unattended weather damage will of course only get worse, as the compromised or exposed roofing material is immediately more vulnerable to further weather damage.
Roof Flashing
Roof flashing is the material used to direct water away from otherwise vulnerable parts of the roof, such as at the edges and joins. It will be used around skylights or where the roof meets walls/parapets, to prevent water from getting in between the two.
Flashing is usually made from very durable and weathertight material, such as galvanised steel. However, over time the fastenings that bond the flashing to the substrate can become loosened. This is one of the most common causes of roof leaks, as the flashing covers vulnerable sections of your roof. Most leaks are due to flashing in need of repair, so once again it’s important to do maintenance checkups and manage any problems before they emerge.
Blistering
When moisture or air gets trapped within the layers of the flat roof cover, it can separate them and cause a visible blistering or bubbling effect. Different weather conditions and changes can contribute to and worsen the underlying problem, causing the blisters to grow on a daily basis. Look out for any raised, spongy patches during maintenance surveys to spot blistering early.
Guttering/Clearing
It’s wise with any roof to make sure that the gutters and drainage systems aren’t blocked with leaves and debris. With flat roofs, it’s important to check and regularly clear the whole roof. Because it is a flat roof, it can acquire a build-up of debris anywhere. Flat roofs are more vulnerable therefore to leaf mould, moss buildup and other potential obstructions to drainage. These materials can contribute to ponding or cause damage to the flat roof cover directly.
Fortunately, while flat roofs are more vulnerable to certain types of damage, maintaining them is on the other hand much easier than with sloped roofing.
Finding a Flat Roof Contractor
For More information and advice, or for professional service enquiries, contact your flat roof contractors. If you’re looking for flat roofing services, B & D Roofing and Building has been commercially and domestically flat roofing for generations. Before searching for ‘flat roofing Fife’, Edinburgh, or anywhere in East Central Scotland, contact us today for expert advice on refurbishment, repair, or installation of flat roofs.
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