Asset 42

THERMAL RATED
STEEL DOORS

U-VALUE PERFORMANCE AS LOW
AS 1.3 W/m²K

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Therma-Line is Design & Supply’s latest generation of thermally efficient steel doorsets, engineered to provide a thermally efficient doorset with an outstanding thermal performance whilst maintaining the strength, durability, and security expected from a steel solution.

With a U-Value performance starting from 1.3 W/m²K, our Therma-Line doorsets are designed to exceed Part L compliance of the Building Regulations and is suitable for both new-build and refurbishment projects – without compromising on robustness, lifespan, or design flexibility.

Manufactured in the UK, Therma-Line provides a reliable solution for projects where energy efficiency, compliance, and long-term performance are critical.

APPLICATIONS:

Therma-Line steel doorsets are suitable for a wide range of projects, including:

  • Commercial and office buildings

  • Industrial units and warehouses

  • Public-sector buildings

  • Education facilities

  • Healthcare environments

  • New-build developments requiring Part L compliance

  • Refurbishment and replacement projects in existing buildings

Wherever external doors are required to meet strict thermal performance targets, Therma-Line offers a dependable steel solution.

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KEY FEATURES

  • Superior thermal performance
    Designed to meet and exceed current Part L requirements.

  • Steel doorset construction
    Constructed from 1.5mm galvanised steel with a mineral core

  • High-performance insulated core
    Minimises heat transfer and improves overall energy efficiency.

  • Durable steel frame and leaf
    Maintains structural integrity in demanding environments.

  • UK manufactured
    Ensures consistent quality, reliable lead times, and full technical support.

  • Bespoke configurations available
    Available as Single or Double doorsets opening Inward or Outward.

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PRODUCT SPECIFICATIONS:

Thermal Performance: U-Value performance as low as 1.3 W/m²K
Materials: Door Leaf: Manufactured from 1.5mm strength and durability.
Frame: Constructed from 1.5mm Steel to ensure reliability.
Door Leaf Styles: Available in single, double and leaf and a half configurations.
Construction: Double-skinned construction with interlocking edges and bonded mineral wool core.
Finish: Doors come with a pre-treated and primed powder-coated finish, providing protection against corrosion and environmental factors. We offer over 350 colours and options for a coastal grade finish.
Vision Panels: In door visions can be supplied using thermally rated glass; however, the U-Value must be considered an estimated performance at this time.
Louvre Panels: Lourves are available but U-Value performance will be affected - contact our team for more information.
Hardware: We offer a wide range of hardware options including Personnel, Panic & Access Control. Hardware components can also affect overall U-Value results - if you have specific requirements please contact our team.

BENEFITS

Improved Energy Efficiency

Therma-Line doorsets help reduce heat loss through external openings, supporting lower energy consumption and improved building performance.

Part L Compliance

With a U-Value performance as low as 1.3 W/m²K, Therma-Line supports compliance for both new-build and replacement external steel doors, giving specifiers confidence at design stage.

Durability

Steel construction delivers long-term durability, making Therma-Line suitable for high-traffic and exposed environments where performance must be maintained over time.

Reduced Maintenance Requirements

Durable materials and engineered components contribute to a longer service life and lower ongoing maintenance costs.

Suitable for New-Build and Refurbishment

Whether replacing existing doors or specifying for new projects, Therma-Line offers flexibility across a wide range of building types.

Specialist Expertise

Designed and manufactured by Design & Supply, with decades of experience in high-performance steel doorsets.

WHY DESIGN & SUPPLY

Trust in the strength and reliability of our Doors to shield your spaces. With an amalgamation of cutting-edge design and unwavering quality, our doors offer an investment in both security and peace of mind. Choose the best, choose protection. Choose our Doors.

FAQ'S

Absolutely, we offer a broad selection of security products that meet Secured by Design requirements. Specifically, our LPS1175 range aligns with these standards.

Yes, we provide comprehensive support from initial Project Estimation all the way through to Installation.

Yes, we have the capability to integrate access control features into our fire-rated doors, spanning both the steel door and glazed door collections.

Yes, we offer delivery services throughout the entire UK.

Yes, we provide installation services across all locations within the UK.

We offer varying warranties depending on the type of door and product. Please check the specific product’s warranty for more details or contact our support team for further information.

Yes, we offer custom door solutions to meet specific project requirements. Our team can work with you to design and manufacture doors tailored to your needs.

Absolutely, we can provide detailed technical specifications for all our products. Please contact our technical support team, and they will assist you with the necessary information.

Our doors are made from high-quality galvanized steel, with the option of upgrading to stainless-steel, ensuring longevity and security. Specific material details are available for each product.

ELEVATE YOUR STANDARDS WITH OUR FIRE RATED STEEL DOORS

CONTACT US TODAY!

When it comes to protecting lives and assets, there’s no room for compromise. Invest in the assurance of top-tier fire safety with our meticulously designed Fire Rated Steel Doors. Whether for warehouses, offices, schools, or any other application, our doors are tailored to exceed your expectations.