A tapered roofing system, also referred to as a cut-to-falls insulation system, is a method of creating a slope or ‘fall’ on a flat roof. These systems are designed to ensure efficient water runoff and enhance thermal performance - two of the most critical factors in both new-build and refurbishment flat roofing projects.
By incorporating pre-angled insulation boards into the roof build-up, you can achieve a consistent and reliable slope that addresses long-standing issues associated with flat roofs; such as water ponding, leaks, and reduced energy performance.
What use a Tapered Roofing System?
Flat roofs, by their very nature, are prone to holding water. Without adequate drainage, this can lead to:
- Structural damage
- Water ingress and roofing membrane failure
- Cold bridging and condensation
- Vegetation growth and roof deck degradation
A properly designed tapered insulation system prevents these problems by guiding rainwater toward drainage points. It provides both practical and performance benefits without the added structural weight of traditional screed or timber fall systems.
Designing for British Standards: 1:60 to Achieve 1:80 Falls
To comply with BS 6229:2018 (Flat Roofs with Continuously Supported Flexible Waterproof Coverings), roofs must be designed to achieve a finished fall of no less than 1:80. However, to accommodate construction tolerances, deflection, and settlement, the design should aim for a 1:60 fall. This ensures the roof performs as intended, even once construction tolerances and long-term movements are taken into account.
A tapered insulation system offers the ideal way to achieve this. It allows designers and contractors to control the falls accurately without relying on potentially imprecise timber firrings or screeded slopes.
Tapered Systems vs. others options in Refurbishment Projects
When refurbishing an existing flat roof, tapered insulation systems offer clear advantages over traditional timber firrings, including:
- Faster Installation
Tapered insulation can be laid directly over the existing structure, reducing the need for extensive structural works or drying times associated with screed or timber-based fall solutions. - Reduced Moisture Risk
Unlike screeds, which introduce water into the roof build-up and require curing, tapered insulation is dry-installed and avoids adding unnecessary moisture to the system. - Integrated Insulation
Whereas firrings simply provide a slope and require a separate layer of insulation, tapered boards combine both functions—streamlining the installation and improving overall thermal performance.
Key Benefits of Tapered Roofing Systems
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Improved Drainage – Prevents ponding and related issues by creating a consistent fall toward drainage outlets
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Enhanced Thermal Efficiency – High-performance insulation improves energy performance and reduces heat loss
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Quicker Project Delivery – Minimises installation time compared to screed or timber build-ups
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Lighter Load – Reduces structural burden, especially critical in retrofit applications
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Extended Roof Lifespan – Mitigates water retention issues that commonly degrade roof membranes and decks
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Compliant with British Standards – Helps achieve design-to-fall requirements of 1:60 to ensure 1:80 effective performance
Other Considerations When Improving Roof Falls
When planning a refurbishment that involves improving or correcting roof falls, it’s important to consider more than just the insulation and slope. Key technical factors include:
- Rainfall Calculations
Designs must account for local rainfall data to ensure drainage systems can handle expected volumes. This includes consideration of outlet capacity, layout, and fallback scenarios in the event of extreme weather. - Structural Constraints
Existing parapet heights, upstand heights, and service penetrations must be evaluated to ensure the new fall system integrates without creating detailing or compliance issues. - Thermal Bridging and Condensation Risk
Proper integration with vapour control layers, insulation continuity, and deck performance is essential to avoid cold bridging and condensation within the build-up.
All of these factors fall within the remit of RAM Building Consultancy, who bring expertise across technical design, product compatibility, and compliance.
How RAM Building Consultancy Can Help
At RAM Building Consultancy, we specialise in delivering complete tapered roofing solutions. Whether it's a refurbishment of an aging flat roof or a new-build project requiring precise drainage design, our team supports every stage from concept to completion.
Our Services Include:
- Technical Design & Layouts
Custom tapered insulation schemes including hips, valleys, and directional falls, always designed to meet or exceed British Standards. - Full Roof Surveys & Assessments
In-depth site analysis including rainfall intensity reviews, outlet placement, and compliance checks. - Project Oversight & Management
From specification through to delivery and post-installation inspections, we ensure the system performs exactly as intended.
With RAM's expertise, you can be confident your tapered roofing system will deliver optimal drainage, thermal performance, and regulatory compliance.
Let’s Talk About Your Roof
If you’re planning a roof refurbishment or facing ponding issues on an existing flat roof, RAM Building Consultancy is here to help. Our team will design and deliver a tapered roofing solution that’s fast, efficient, compliant, and built to last.
Get in touch to arrange a consultation or request a tailored tapered insulation layout for your project.
