Flat roofing has become an increasingly popular choice in homes across the UK, celebrated for their sleek, modern design and practicality. Many new builds are opting for flat roofs over pitched roofing due to the cost-saving benefits involved, not to mention the greater functionality a flat roof can bring to a home. This article will explore the world of flat roofs, assessing their appeal, common materials, and the installation costs involved.
What Is a Flat Roof?
Flat roofs are a type of roof with a nearly level surface, characterised by a slight pitch - usually no more than 10 degrees - to allow for water runoff. Unlike pitched roofs, which have a steep incline and prominent peaks, flat roofing is seen as a more modern and aesthetically pleasing approach to residential and commercial properties; their minimal slope makes them easier to construct and maintain while offering design flexibility for various building types.
Flat roofs usually come in two types, warm deck roofs and cold deck roofs. A warm deck roof is the most commonly and successfully used. This design involves placing insulation above the roof deck, ensuring the entire structure stays protected from the extremes of hot and cold weather, and reducing the risk of condensation within the roof layers.
Although they are no longer recommended by roofing experts, many properties have a cold deck roof installation method, where the insulation sits below the roof deck. This method is considered to be less energy efficient and can lead to condensation issues if not installed properly.
What Are the Pros and Cons of a Flat Roof?
Flat roofs offer unique advantages to homeowners but require careful planning and maintenance to address the specific challenges associated with them. At Empire Roofing, we always advise the clients we work with on the pros and cons of flat roofing, like:
Pros of Flat Roofing:
- Space Efficiency: Flat roofs maximise usable space by eliminating sloped ceilings and creating additional outdoor space for terraces, rooftop gardens, or solar panels.
- Ease of Maintenance: Flat roofs provide easy access for maintenance tasks like gutter cleaning, inspections, and roofing repairs.
- Cost-Effectiveness: Flat roofs often require fewer materials and are faster to install than pitched roofs, lowering general installation costs.
- Versatility: The flat surface of the roof can accommodate installations like external HVAC units, satellite dishes, and even recreational spaces.
- Modern Aesthetic: A flat roof’s minimalist design complements contemporary architectural styles, which are particularly desirable in modern homes.
Cons of Flat Roofing:
- Drainage Issues: Without a steep slope, flat roofs rely on carefully designed drainage systems, which may become clogged or overwhelmed during heavy rain.
- Weather Exposure: Flat roofs can wear faster due to prolonged exposure to footfall, rain, and snow pooling. Proper waterproofing and regular maintenance are essential.
- Insulation Needs: Ensuring adequate insulation, particularly for colder areas of the country, may require additional upfront costs.
What Are the Most Popular Flat Roof Materials?
If you’re considering a flat roof for your home, these are some of the most popular and successful materials to use. If you need extra advice, please don’t hesitate to contact our roofing experts and we’ll provide you with further guidance.
1. Glass-Reinforced Plastic (GRP)
GRP is a lightweight but durable material that is made by reinforcing polyester resin with glass fibres. One of the most robust and popular options for a flat roof, GRP offers high resistance to extreme weather, requires minimal maintenance, and provides a sleek, modern finish to complete the look. Typically, your GRP roof will last between 25 to 50 years with proper installation and maintenance.
2. Single-Ply Membranes (Such as EPDM)
Single-ply roofing materials, such as Ethylene Propylene Diene Monomer (EPDM), are synthetic rubber membranes known for flexibility and weather resistance, making them a handy material for flat roofs. Single-ply membranes are an excellent choice for both residential and commercial flat roofs due to the excellent insulation they provide, contributing to a property’s energy efficiency, and they will usually last between 25 to 40 years, protecting your investment.
3. Lead (Code 5 to 8)
For projects looking for a traditional, “high-end” finish, lead is usually the best choice to achieve this. Lead offers exceptional longevity, lasting over 100 years in some cases when proper installation is practised. Lead is often a standout choice for high-end or historic buildings with a flat roof due to its timeless look, but it is a heavy material, requiring proper structural support.
4. Flat Roof Felt
Traditional flat roof felt is another very popular choice, particularly for those working with a tighter budget since it is a more affordable, simple-to-install option. However, traditional felt has a shorter lifespan than many other flat roof materials, usually lasting between 15 to 25 years. Modern variations of this material offer greater durability, such as modified “torch-on” bitumen; this is applied using a blowtorch to bond layers securely, providing more resistance to extreme weather.
5. Green Alternatives
Green flat roofs, also known as “living roofs”, involve covering the roof with vegetation and a growing medium over a waterproof membrane. This approach is environmentally friendly and offers excellent insulation, becoming increasingly popular in cities, but requires ongoing maintenance which can cause the costs to mount up.
What Material Should I Choose For My Flat Roof?
There isn’t a one-size-fits-all answer to which flat roof material is the best - it depends on your specific needs, budget, and the type of property you own. For example, lead has the greatest longevity but typically costs the most, whereas modified bitumen is more cost-effective but less durable. GRP and single-ply membranes are typically the most popular choices for modern homes, offering the best balance between cost, durability, versatility, and low maintenance for residential and commercial properties.
How Much Does a Flat Roof Cost?
The cost of a flat roof massively depends on the material choice you opt for, as well as the size of the roof, the complexity of its design, and the level of access needed to reach it. You’ll typically pay between £50 to £130 per m², with traditional felt on the lower cost-side, and lead on the higher side.
- GRP: £80 to £120 per m²
- EPDM: £60 to £80 per m²
- Lead: £80 to £130 per m²
- Traditional Felt: £20 to £40 per m²
- Torch-On Felt: £30 to £50 per m²
- Green Alternatives: £50 to £100 per m²
How Does the Installation Process Work for Flat Roofs?
The installation of a flat roof involves several carefully executed steps to ensure durability, waterproofing, and structural integrity. While the exact process varies depending on the roofing company and material chosen, the general stages are outlined below:
1. Preparing the Roof Base
The existing roof structure will be inspected to ensure it can support the new roof material, which may require repairs or reinforcements to be made. The old roofing material will be removed, and any uneven areas will be levelled for proper adhesion. If needed, a flat roof deck will be laid as the foundation, typically made of plywood or oriented strand board (OSB).
2. Adding Insulation
Most roofers will opt for the warm deck insulation approach, as highlighted earlier, where insulation is placed above the decking to create a thermal barrier and reduce the risk of condensation.
3. Applying Waterproof Layers
- Flat Roof Felt: Traditional felt is laid in overlapping layers, bonded with bitumen adhesive, or a modified bitumen approach is taken, where a blowtorch melts and adheres to the layers to create a watertight seal.
- GRP: A resin base coat is applied, followed by fibreglass matting. To ensure a seamless and waterproof finish, a topcoat is added to the fibreglass matting.
- Singly-Ply Membranes: The membrane is rolled out and glued or mechanically fastened to the decking, and seams are sealed to prevent any leaks.
- Lead Roofs: Sheets of lead are accurately measured, cut, and welded or soldered to create a watertight barrier. Proper care will be taken to allow for thermal expansion.
4. Installing Flashing and Edging
Flashing and edging trims are installed to protect vulnerable areas of the flat roof, such as joints, edges, and corners. This is an essential step that ensures a clean finish with additional waterproofing.
5. Final Inspections and Testing
An inspection will be carried out to assess the flat roof for potential weak points, such as improperly sealed seams or insufficient drainage. The drainage system will be tested to ensure the water runs off correctly without pooling, which could lead to leaks.
Maintenance Tips for Flat Roofing
Proper maintenance is essential for the longevity and performance of a flat roof - here are some of our key tips to keep your flat roof in excellent condition:
- Regular Inspections: Using a traditional or drone roof survey, check for cracks, leaks, or drainage issues at least once a year, or after any severe weather.
- Clean Debris: Remove any leaves, branches, and dirt regularly to prevent blockages.
- Ensure Proper Drainage: Clear any gutters, downspouts, and drains to prevent water backup.
- Repair Damage Promptly: Sort any small issues as soon as you notice them to prevent them from causing wider problems. Always consult an expert for major repair needs.
- Protect the Roof Surface: Minimise foot traffic where possible, and apply UV-resistant coatings to extend the lifespan of your roofing material.
- Control Vegetation: The buildup of moss and algae can cause drainage issues, so address this as promptly as possible.
How to Choose the Right Roofing Contractor
Choosing the right roofing specialist is important to ensure your flat roof is a lasting investment for years to come. Look for a contractor with specific expertise in flat roofing and the materials you’re considering, such as EPDM or GRP, and read related reviews that confirm the success of previous projects.
The best roofing contractors should place a strong emphasis on clear communication and professionalism, demonstrating a strong safety record for each and every project. Don’t be afraid to ask questions about the best materials to use, how long the process could take, and any other concerns or queries you may have - use the expertise that a roofer has to your advantage!
Choose Empire Roofing for Quality Flat Roof Systems
If you’re based in and around Oxfordshire and are looking to have a flat roof installation, Empire Roofing offers a range of different successful solutions to create a flat roof you’re proud of. Every installation is designed with longevity in mind, paying attention to small details that could cause future issues if not addressed. To schedule a consultation, or ask any questions, please contact us today at 01993 259226, or send a message via our contact form.
