Types of Flat Roofing Systems
A practical guide to felt, EPDM, liquid coatings, GRP, metal roofing and single-ply membranes for commercial and industrial roofs.
Choosing a flat roofing system is not just about picking a product. The right roof depends on the building, the existing roof condition, the substrate, drainage, detailing, budget, disruption and long-term maintenance.
Flat roofing systems covered:
- Bitumen and felt roofing
- EPDM rubber roofing and GRP
- Liquid-applied roof coatings
- Metal roofing and overcladding
- PVC and TPO single-ply membranes
Choosing the right flat roofing system
When it comes to choosing a product for a flat roof, there are many systems available. Some are better suited to small domestic roofs, while others are more suitable for commercial, industrial, education, public-sector and warehouse roofs.
Modern Roofing has worked with many flat roofing systems over the years, including felt, liquid-applied systems, single-ply membranes, metal roofing, GRP and roof refurbishment systems. The correct solution should be based on the roof condition, building use and long-term value rather than simply the product name.
This updated guide explains the most common types of modern flat roofing systems and where each one may be suitable.
Direct answer
The main types of flat roofing systems are felt or bitumen, EPDM rubber, liquid-applied coatings, GRP fibreglass, metal roofing, TPO and PVC single-ply membranes. For commercial and industrial flat roofs, single-ply membranes, liquid-applied systems, metal roofing and overcladding are often considered because they can suit larger roof areas and more demanding building requirements.
Flat roofing systems comparison
The table below gives a practical overview. It is not a substitute for a roof survey, but it helps explain why different roof systems are used on different buildings.
| System | Common use | Key consideration |
|---|---|---|
| Felt / bitumen | Domestic and some smaller commercial flat roofs | Quality depends heavily on product choice, detailing and installation. |
| EPDM rubber | Simple flat roofs and smaller roof areas | Substrate preparation, adhesion, wind uplift and perimeter detailing matter. |
| Liquid-applied roofing | Complex details, gutters and roof refurbishment | Weather, substrate condition and preparation are critical. |
| Metal roofing | Industrial units, factories, warehouses and pitched commercial roofs | Requires suitable pitch, correct laps, fixings and detailing. |
| PVC single-ply | Commercial, industrial, education and public-sector flat roofs | Requires trained installation, correct welding, detailing and roof build-up. |
| TPO single-ply | Commercial and industrial flat roofs | Specification, product history, detailing and installer experience matter. |
| GRP fibreglass | Smaller flat roofs and domestic applications | Rigid system; deck movement and weather during installation must be considered. |
| Overcladding | Industrial and commercial roof refurbishment | Existing roof and structure must be assessed before recommendation. |
1. Bitumen and felt roofing systems
Bitumen-based flat roofing includes traditional built-up felt systems, torch-on felt and modified bitumen membranes. Felt roofing has been used in the UK for many years and remains common on some domestic, commercial and smaller flat roof areas.
Felt systems are widely available, many contractors can install them, and they can offer good puncture resistance when installed correctly.
The quality depends heavily on product, number of layers, detailing and workmanship. Torch-applied systems also involve hot works, which need careful management.
For many larger industrial and commercial roofs, clients now compare felt with single-ply membranes, liquid-applied systems, metal roofing or overlay refurbishment options.
2. EPDM rubber roofing
EPDM rubber roofing is a flexible sheet membrane system often used on smaller flat roofs, extensions, garages and some commercial roofs. It is commonly promoted because large sheets can reduce the number of field seams on simple roof areas.
EPDM can be quick to install on simple roofs, and the material itself has been used successfully on many projects where the roof is suitable.
As with any adhered system, substrate preparation and bonding are critical. Wind uplift, edge details, perimeter fixings, penetrations and drainage need careful attention.
3. Liquid-applied roofing systems
Liquid-applied roofing systems are installed as coatings that cure to form a waterproof layer. They can be very useful on complex roofs with awkward details, penetrations, upstands, gutters and areas where sheet membranes may be harder to detail.
Liquid systems can be excellent for roof refurbishment, gutter lining, complex detailing and extending the life of suitable existing roof coverings.
Preparation is critical. The surface must be clean, dry and suitable for coating. Weather conditions also matter, especially in Scotland.
View Industrial Roof Refurbishment Scotland | View Industrial Gutter Lining Scotland
4. Metal roofing systems
Metal roofing systems include coated steel sheeting, aluminium standing seam, zinc, copper and other profiled or standing seam systems. Metal roofing is widely used on industrial and commercial buildings across Scotland.
Metal roofing is strong, durable and well suited to many industrial and commercial buildings. It can be installed quickly and specified in different colours and profiles.
Metal roofing normally requires suitable pitch and correct detailing at laps, fixings, gutters, flashings and penetrations.
View Metal Roofing Systems Scotland | View Industrial Roof Overcladding Scotland
5. PVC single-ply membrane roofing
PVC single-ply membrane roofing is widely used on commercial, industrial, education, healthcare and public-sector buildings. Systems such as Sika single-ply membranes are commonly specified for flat roofs where a manufactured membrane, hot-air welded laps and clean detailing are required.
PVC single-ply membranes are manufactured under controlled conditions and installed as sheet membranes. Laps are hot-air welded, creating a strong waterproof joint when installed correctly.
Single-ply roofing should be installed by trained operatives using the correct equipment. Detailing, outlets, upstands, fixings and roof edges all matter.
Single-ply membranes are often chosen for commercial and industrial flat roofs because they are lightweight, clean to install, suitable for larger roof areas and effective around upstands, outlets, penetrations and perimeter details.
View Single Ply Membrane Roofing Scotland | View Sika Single Ply Membranes
6. TPO single-ply membrane roofing
TPO is another type of single-ply membrane used on flat roofs. Like PVC, it is supplied as a sheet membrane and the laps are usually hot-air welded.
TPO can be suitable for commercial and industrial flat roofs and offers many of the same broad advantages as single-ply systems.
The suitability of TPO depends on the manufacturer, product, specification, detailing and installer experience.
7. GRP fibreglass roofing
GRP roofing is a rigid liquid-applied fibreglass system often used on small domestic flat roofs, bay roofs and some smaller commercial applications.
GRP can provide a hard, seamless surface when installed correctly and can work on smaller roofs where the deck is suitable.
GRP is more rigid than many other flat roofing systems, so deck movement, substrate condition, weather and workmanship are important.
8. Industrial roof overcladding
Overcladding is a roof refurbishment method where a new roof system is installed over an existing roof covering, usually on industrial or commercial buildings. It can improve weather protection, appearance and thermal performance without always requiring a full strip-off.
Overcladding can reduce disruption, avoid unnecessary strip-out and extend the service life of an existing building.
The existing roof, structure, fixings, rooflights, gutters, drainage and roof build-up must be assessed properly before overcladding is recommended.
Which flat roofing system is best?
There is no single flat roofing system that is best for every building. A small domestic garage, school roof, warehouse, factory, commercial office and public-sector building can all require different solutions.
For simple small roofs
Felt, EPDM or GRP may be considered depending on the deck, detailing, budget and roof use.
For complex details
Liquid-applied systems can work well around penetrations, gutters, upstands and awkward roof shapes.
For commercial flat roofs
Single-ply membrane systems are often suitable for larger commercial, industrial and public-sector flat roof projects.
Why Modern Roofing often recommends Sika and single-ply systems
Modern Roofing has experience with many different flat roofing systems, but single-ply membrane roofing remains one of the most practical choices for many commercial and industrial flat roofs. Sika single-ply systems are commonly used where clients need a specified membrane system, trained installation, clean detailing and a roof finish suitable for larger commercial and public-sector buildings.
That does not mean single-ply is always the answer. On some roofs, a liquid-applied coating, metal roof system, overcladding or targeted repair may be more suitable. The correct recommendation depends on the roof condition and the building.
Final advice
Before choosing a flat roofing system, do not look only at the product name or headline guarantee. Look at the full roof design, the contractor’s experience, the detailing, the roof build-up, the drainage and whether the system is suitable for your building.
Industrial Roofing Scotland
Modern Roofing (Scotland) Ltd provides commercial and industrial roofing services across Scotland, including roof repairs, refurbishment, overcladding, gutter lining, Sika systems, roof surveys and planned maintenance.
Types of Flat Roofing Systems FAQs
What are the main types of flat roofing systems?
The main types include felt or bitumen, EPDM rubber, liquid-applied coatings, GRP fibreglass, metal roofing, PVC single-ply and TPO single-ply membranes.
What flat roofing system is best for commercial buildings?
It depends on the building, but single-ply membranes, liquid-applied systems, metal roofing and overcladding are commonly considered for commercial and industrial roofs.
Is single-ply membrane better than felt?
Single-ply membrane can be a strong option for larger commercial roofs because of its sheet format, hot-air welded laps and suitability for modern warm roof build-ups. Felt can still be suitable for certain roofs when specified and installed correctly.
When should a roof be surveyed before choosing a system?
A survey is recommended when the roof is leaking, ageing, holding water, has insulation concerns, or when you are deciding between repair, overlay, refurbishment or full replacement.
Need advice on the right flat roofing system?
For commercial flat roofing, industrial roof refurbishment, single-ply membrane roofing or roof surveys in Scotland, contact Modern Roofing (Scotland) Ltd.