Types Of Roofing Systems: A Complete Guide for Irish Homeowners

Choosing the right roof for your home is not just about appearances. It is about protection, longevity, compliance with regulations, and overall value. For many Irish homeowners, the key decisions are now happening on flat and low-slope roofs – extensions, dormers, balconies, garages and terraces – rather than on traditional pitched roofs.

At QBM, we specialise in flat roofing systems and accessories supplied to professional roofing contractors and design teams across Ireland. We do not sell tiles or asphalt shingles; instead, we focus on robust, modern flat roof membranes that perform in Ireland’s wet, windy climate and meet current fire and thermal requirements.

If you are planning a new extension, upgrading an existing flat roof, or considering a green or blue roof, understanding your options will make the process far less daunting.

This guide explains the main flat roofing systems QBM supply, where each is typically used, and which might best suit your project.

Flat Roofing with QBM: What We Actually Supply

Rather than every roofing product on the market, QBM focuses on a set of proven systems:

• Bituminous torch-on membrane systems (multi-layer “felt” systems from our General Membrane range)

• PVC single-ply membrane systems (from our FDT range)

• EPDM rubber roofing kits for domestic extensions, sheds and garages

• Associated insulation build-ups (warm and inverted roofs)

• Green and blue roof build-ups using our flat roof membranes as the waterproofing layer

• Aluminium edge trims and metalwork to finish and protect flat roof edges and details

The sections below walk through each of these in more detail.

Bituminous Torch-On Membrane Systems

Bituminous membranes – often referred to as “felt roofs” – remain a core solution for flat roofs in Ireland, especially for warm roof build-ups on extensions and refurbishments.

QBM supplies high-performance, multi-layer bituminous systems from our General Membrane range, typically comprising:

• A vapour control layer

• A base/intermediate layer

• A mineral or cap sheet as the final waterproofing layer

Key advantages

• Proven performance in Ireland’s wet climate

• Multi-layer build-up offers strong redundancy and robustness

• Suitable for warm roof, cold roof and overlay refurbishment systems

• Wide range of finishes and mineral colours

• Excellent compatibility with traditional detailing methods

Typical applications

• House and kitchen extensions

• Refurbishment of existing felt roofs

• Apartment blocks and communal walkways

• Roofs where a robust, foot-traffic-resistant finish is required

Considerations

• Installation is normally by gas torch and must be carried out by experienced roofing contractors

• Correct design of insulation and vapour control is critical to avoid condensation

• Weight is higher than single-ply systems, so structure should be checked on refurb projects

QBM can assist your architect or contractor in selecting the correct Bitumenman system to meet thermal, fire and durability requirements.

Metal Roofing: Long-Term Performance

Metal roofing has come a long way from the agricultural buildings and industrial units where it originated. Modern metal roofs offer homeowners impressive durability that can stretch 50 years or more with minimal fuss.

The material itself resists fire, doesn't rot, and handles wind exceptionally well. This makes metal roofing particularly attractive for exposed properties or coastal homes where salt air can accelerate deterioration in other materials.

Benefits worth noting:

• Exceptional lifespan (40-70 years typical)

• Lightweight compared to tile systems

• Energy-efficient with reflective coatings

• Low maintenance requirements

• Recyclable at the end of life

Metal roofs come in several materials. Steel provides strength and affordability. Aluminium resists corrosion better, which helps in coastal regions. Copper and zinc offer distinctive appearances that develop attractive patinas over time, though they cost considerably more.

Installation costs run higher than asphalt shingles initially. But when you factor in longevity and reduced maintenance, the numbers often balance out. Some homeowners worry about noise during rainfall, though proper insulation typically addresses this concern.

PVC Single-Ply Membrane Systems (FDT)

PVC single-ply membranes provide a lightweight, modern alternative to multi-layer bituminous systems. QBM supplies FDT PVC membranes that are widely used on both domestic and commercial projects.

These systems typically consist of a single waterproof membrane that is:

• Mechanically fixed,

• Adhered, or

• Ballasted (for inverted roofs, green roofs or terrace finishes).

Key advantages

• Lightweight – ideal where structural capacity is limited

• Fast installation and clean detailing

• Heat-welded seams create durable, watertight joints

• Well-suited to complex details such as upstands, rooflights and parapets

• Often selected as the waterproofing layer beneath green and blue roofs

Typical applications

• New build extensions and flat roof areas

• Apartment and commercial roofs

• Inverted roofs with paving, ballast or decking

Green and blue roof systems where consistent water-tightness is essential

Considerations

• Must be installed by trained PVC single-ply contractors with the correct welding equipment

• Requires appropriate substrate preparation and fixings or adhesives

• Needs to be correctly detailed at junctions, penetrations and perimeters

QBM’s technical team can help design a complete FTT system, including fixings, vapour control, insulation, and edge details.

Elevate EPDM Rubber Roofing Kits

For smaller domestic projects – such as single-storey extensions, sheds, home offices and garages – EPDM rubber offers a straightforward, cost-effective solution.

QBM supplies EPDM roofing kits that typically include:

• A single-piece EPDM membrane cut to size

• Appropriate adhesives (water-based and/or bonding adhesive)

• Pre-formed corners and accessories where required

• Aluminium or GRP edge trims to provide a neat, secure finish

Key advantages

• Simple, quick installation for competent roofing contractors

• Fewer seams: many small roofs can be done in a single sheet

• Good resistance to UV and weathering

• Lightweight with minimal impact on structure

• Ideal for domestic-scale flat roofs

Typical applications

• Kitchen or living room extensions

• Garden rooms, sheds and home offices

• Garage roofs

• Replacement of ageing felt on small domestic roofs

Considerations

• Substrate must be smooth and properly prepared

• Detailing around penetrations and rooflights requires care

• Dark colour absorbs heat, so correct insulation build-up is important

Our EPDM kits are designed to make specification and ordering simple, while ensuring all required trims and adhesives are included.

Warm Roof and Inverted Roof Build-Ups

Beyond the waterproofing layer itself, how your flat roof is insulated and built up has a major impact on performance.

QBM provides guidance and specifications for:

Warm Roof Systems

• Insulation above the structural deck

• Vapour control layer on the warm side of insulation

• Waterproofing membrane on top (General Membrane Bitumen, FDT PVC or Elevate EPDM, depending on system)

Benefits:

• Reduces risk of condensation when correctly designed

• Improves thermal performance and energy efficiency

• Keeps the structure warm, reducing thermal stress

Inverted Roof Systems

• Waterproofing membrane directly on the structural deck

• Rigid insulation laid on top of the membrane

• Ballast, paving, decking or green roof build-up above

Benefits:

• Membrane is protected from UV and mechanical damage

• Ideal for roof terraces, balconies and green/blue roofs

QBM can supply the waterproofing and associated details, and work with your design team to ensure that the overall build-up meets current Irish Building Regulations.

Green & Blue Roof Systems

Green and blue roofs are increasingly popular in Irish urban areas, and QBM’s membranes are often used as the waterproofing layer beneath these systems.

Green roofs

• Vegetation layer (sedum, wildflower or intensive planting)

• Growing medium and filter layer

• Drainage and protection layers

• Waterproofing membrane (General Membrane Bitumen, FDT PVC or Elevate EPDM) beneath

Blue roofs

• Designed to temporarily store rainfall on the roof

• Controlled outlets regulate the release of water to the drainage system

• Often combined with a green roof build-up

Key advantages:

• Manage stormwater and reduce pressure on urban drainage

• Enhance biodiversity and visual amenity

• Improve thermal and acoustic performance

• Can contribute to planning compliance on certain developments

Because the waterproofing layer is buried beneath soil, ballast and drainage layers, reliability is critical. QBM works with designers and contractors to choose the right membrane system, protection layers, and edge details for these roofs.

Choosing the Right System for Your Home

Below is a simplified comparison of the main flat roof systems QBM supply for domestic projects. Actual performance and cost will depend on the specific build-up and project details.

Roofing System	Typical Lifespan (when properly installed)	Climate Suitability (Ireland)	Maintenance Level	Typical Initial Cost*
Bituminous Torch-On	20–30+ years	Excellent	Medium	Low–Medium
PVC Single-Ply (FTT)	25–30+ years	Excellent	Low–Medium	Medium
EPDM Rubber (QBM Kits)	20–30 years	Very Good	Medium	Low–Medium
Warm Roof Build-Up	As per membrane	Excellent	Medium	Medium
Inverted Roof Build-Up	As per membrane	Excellent	Low–Medium	Medium -High
Green / Blue Roof (over QBM membranes)	Depends on system; membrane protected	Very Good	Higher (for planting)	High (due to full build-up)

*Indicative relative cost only – excludes structural work and is subject to project-specific design.

Think about your plans too. If you're staying long-term, premium options make more sense. Shorter timelines might favour cost-effective solutions. Energy efficiency considerations can influence the decision, particularly with rising heating costs.

Choosing the Right System for Your Home

The “best” flat roofing system for your project depends on several factors:

• Use of the roof

  • Simple weatherproof cover (e.g. over a utility room)

  • Terrace, balcony or accessible roof area

  • Green or blue roof

• Structure and loading

  • Existing deck material and condition

  • Available structural capacity for ballast, planting or paving

• Thermal requirements

  • Warm roof vs inverted roof

  • Target U-values for Building Regulations compliance

• Budget and programme

  • Upfront cost vs long-term durability

  • Speed of installation and coordination with other trades

QBM does not install roofs, but we work closely with architects, engineers and roofing contractors to select the most appropriate system and provide project-specific specifications.

Installation and Maintenance Matters

Even the best roofing material performs poorly with substandard installation. Professional installation isn't optional; it's essential. Proper techniques ensure waterproofing, structural integrity, and warranty validity.

Regular maintenance extends any roof's lifespan. Annual inspections catch small issues before they escalate. Clear gutters and drains prevent water backup. Replace damaged components promptly.

At QBM, we emphasise proper installation and ongoing care. A roof is your home's primary defence against Ireland's weather. Investing in quality materials and professional workmanship pays dividends over decades.

Frequently Asked Questions

What roofing system performs best in Ireland's wet climate?

All of QBM’s core systems – General Membrane bituminous systemss, FDT PVC single-ply and Elevate EPDM rubber – are designed to perform in wet, windy conditions when installed correctly.

• Bituminous torch-on systems offer robust, multi-layer protection and have a long track record in Ireland.

• PVC single-ply systems provide heat-welded seams and are often preferred for modern builds, inverted roofs and green/blue roof projects.

• EPDM works very well on smaller domestic roofs where simplicity and speed of installation are priorities.

The key is selecting the right build-up (warm or inverted) and ensuring proper detailing and drainage.

How much does it typically cost to replace a roof in Ireland?

Costs vary depending on:

• Roof size and complexity

• Choice of membrane (bituminous, PVC or EPDM)

• Insulation type and thickness

• Access, safety and detailing requirements

As a broad guide for supply and installation by a professional contractor:

• EPDM on small domestic roofs: typically at the lower end of the cost scale

• Bituminous multi-layer systems: low–medium cost with robust performance

• PVC single-ply: medium cost, particularly for larger or more complex roofs

• Green/blue roofs and inverted terraces: higher cost due to extra layers, insulation, finishes and detailing

QBM can provide material budgets and support your contractor in pricing a QBM-specified build-up, but final installed cost will always come from your chosen roofing contractor.

Flat roofing systems typically run upwards from €120 per square metre, depending on membrane type and insulation thickness. Remember that cheaper options often require replacement sooner, making premium materials more economical long-term. Always obtain multiple quotes from reputable contractors and verify their credentials before proceeding.

Can I install solar panels on any type of roofing system?

Yes, Most roofing systems can accommodate solar panels with proper mounting hardware, though some work better than others. Metal roofing offers ideal conditions; panels attach easily without penetrating the roof surface. All PV installations require careful mounting to prevent leaks. Flat roofs work well for solar arrays, particularly Bitumen and PVC systems. For green and blue roofs, loading, drainage and waterproofing protection layers must be carefully coordinated. The key is working with experienced installers who understand both roofing and solar requirements to ensure waterproof integrity remains intact.

How often should I have my roof inspected professionally?

Bi-annual inspections represent the minimum recommendation for all roofing systems. Schedule checks in autumn before winter weather arrives, allowing time to address any issues discovered. Increase inspection frequency after severe storms, particularly high winds or hail events. Flat roofs and those with complex designs may require more frequent attention due to drainage considerations. Professional inspections identify problems early when repairs cost less and prevent interior damage. Keep records of all inspections and maintenance work performed.

Do QBM deal directly with homeowners?

QBM primarily supplies products and technical support to:

• Roofing contractors

• Architects and design teams

• Developers and main contractors

However, if you are a homeowner planning a project, we can:

• Help your architect, engineer or contractor select an appropriate QBM system

• Provide NBS-style specifications, technical data sheets and typical details

Recommend QBM-approved systems that local contractors can install

How do I know which QBM system is right for my project?

Start with the basics:

1. What is the roof being used for (simple cover, terrace, green roof, etc.)?

2. Is it a new build or refurbishment?

3. What are the structural and thermal requirements?

4. What is your budget and timescale?

Once those are clear, QBM can work with your design team to propose:

• A suitable membrane system

• The correct build-up (warm or inverted)

• Edge, upstand and drainage details

Any additional components such as aluminium trims and accessories

Making Your Decision

Selecting a flat roofing system is a significant investment in your home’s future. The right QBM system, correctly designed and installed by professional contractors, can deliver decades of reliable performance in Ireland’s demanding climate.

QBM’s role is to supply proven flat roofing products and provide technical support – from early design and specification through to on-site queries. Whether you are planning a simple extension or a complex roof with terraces, green roofs or blue roof attenuation, we can help your project team choose and detail the most appropriate solution.

If you or your design team would like project-specific guidance or specifications for a flat roof in Ireland, QBM’s technical department is available to assist.