How Long Does a Flat Roof Last?
Your roof is one of your home’s most important elements, and flat roofs are a common choice in the UK.
If you’re considering a flat roof for an extension, garage or entire property, you are going to want to know how long it will last. A flat roof can last from anywhere from 10 years to more than 40, but this depends on a variety of factors.
In this article, we’ll take a closer look at exactly how long flat roofs last, as well as identify warning signs that your flat roof might need replacing.
Read on for more information…
What is a flat roof?
A flat roof is a type of roof that has a very low pitch (or slope) and appears almost completely horizontal. In practice, it does have a slight slope, usually less than 10 degrees, so it can still allow drainage, guttering and internal drains to remove rain and other moisture. Typically, the roof will be covered with a waterproof membrane to stop water ingress.
Due to its low pitch, the roof can pool if drainage is not adequate, which can have a serious impact on the durability and longevity of the roof.
Benefits of a flat roof
Flat roofs offer a wide range of benefits, including:
- Cost-effectiveness: In many cases, flat roofs do not need as much structural support and materials as pitched roofs, which can reduce their cost.
- Useable roof space: Flat roofs can host terraces, solar panels and roof gardens more easily as there is more usable space.
- Great aesthetics: Flat roofs suit modern architectural styles, creating a clean and minimalist look.
- Simple installation: Waterproof membrane systems can be laid much more easily over a flat deck, with fewer breaks.
- Ease of maintenance: Walking on a flat roof to conduct repairs is much easier and safer than steep-pitched roofs.
While flat roofs offer great benefits, they also come with challenges and require more care when it comes to drainage.
How long does a flat roof last?
In general, a flat roof’s life expectancy ranges from 10 years to more than 40 years. The design, material choice, workmanship and climate all play major roles in exactly how long the roof will last.
Let’s break down the different flat roof types and explain how long they tend to last.
Felt flat roof
The typical lifespan of a felt flat roof is 8 years to 12 years, although sometimes they can last less than 5 years if not well maintained.
Pros of felt flat roofs
- Low initial cost
- Easy to install
- Most roofers are familiar with handling felt material
Cons of felt flat roofs
- It can look unattractive
- The weather can cause it to crack and split easily
- There is a risk of fire
- Organic matter can grow more easily
Glass reinforced polymer fibreglass flat roof
Usually, these flat roofs will last between 15 to 20 years assuming they have been installed properly and are well maintained.
Pros of glass reinforced polymer fibreglass flat roofs
- Extremely durable
- Low maintenance when installed properly
- Great aesthetics
Cons of glass reinforced polymer fibreglass flat roofs
- Can crack if the weather causes the roofs to expand
- Won’t bond to the roof if it is wet
- Can only be laid in certain temperatures
EPD flat roof
These roofs typically last from 15 to 20 years but in some circumstances can last more than 30 years.
Pros of EPD flat roofs
- Cost-effective
- Easy to install
- The material is readily available
Cons of EPDM flat roofs
- Easily punctured
- Damaged by sunlight
- Can look unsightly
PVC flat roof
A PVC flat roof has a baseline lifespan of 20 years, which can be extended to more than 40 years with proper maintenance.
Pros of PVC flat roofs
- Can be installed no matter the weather
- Can save money when fitted over existing systems
- Can withstand harsh weather conditions like sun and frost
Cons of glass reinforced polymer fibreglass flat roofs
- It tends to be more expensive
- Can’t be fitted yourself, it must be done by certified installers
Factors that affect how long a flat roof lasts
The lifespan of a roof depends on a variety of factors including:
- Materials used: Higher quality membranes and adhesives last longer. Using low-cost materials can sometimes wear more rapidly.
- Quality of work: Even the best quality materials can fail if they are installed poorly. Make sure you use reputable installers for the best results.
- Location: In the UK, the roof will face cold, moisture, sun and severe rain and wind. Therefore, homes that are exposed to the elements tend to see wear and tear more quickly.
- Natural elements: Debris, leaves, branches and dirt from natural elements can lead to damage to your flat roof.
- Ventilation: Poor ventilation or insulation can cause heat and moisture to build up on the roof, leading to damage to the membranes.
- Lack of maintenance: Regular checks, promptly dealing with defects and removing standing water properly will extend the life of a flat roof. Without maintenance, even the best roof can deteriorate fast.
Signs your flat roof needs replacing
There are a number of signs that indicate when your flat roof is approaching the end of its life. Here are a few red flags to keep an eye out for:
- Leakages: Water ingress that recurs after repairs is a big sign you need a new roof.
- Flooding: If rainwater does not drain properly and pools for long periods, the membrane will suffer.
- Splitting or cracking: Any ruptures in the surface of your flat roof are signs of the material failing.
- Sagging or low spots: The underlying structure might be failing, causing it to dip.
- Unexpected increases in your energy bills: A degraded roof will not be insulating properly, meaning it is more susceptible to heat loss and leaks.
- Visible UV wear – If the membrane looks aged or worn away, it is a sign that the roof is failing.
If you notice any of these signs, especially if multiple are happening at once, you should seek professional support.
