Collection: Thermally Rated Steel Doors

Insulated steel doors are available in several configurations depending on the required thermal performance (U-value), and whether fire resistance, security certification, or external weather compliance is also required

Standard Insulated Steel Doors

These are heavy-duty steel door sets fitted with insulated cores to improve basic thermal performance compared to non-insulated doors.

Commonly used for:

• Warehouses
• Plant rooms
• Service areas
• Internal/external personnel access

Suitable where improved insulation is required without certified U-value performance.

Thermally Rated Steel Doors

Engineered to achieve measurable U-values, typically down to 1.5 W/m²K.

Features may include:

• High-density insulated cores
• Thermal breaks within frame construction
• Enhanced perimeter seals
• Insulated thresholds

Used where compliance with energy efficiency targets is required.

Thermally Rated Fire Steel Doors

These combine:

• Certified fire resistance
• Thermal insulation performance
• Internal doors tested to BS EN 1634-1
• External fire doors compliant with BS EN 16034 (used with BS EN 14351-1)

Specified where both compartmentation and energy performance are required.

Thermally Rated Security Steel Doors

Can be specified to:

• PAS 24 enhanced security

Combines thermal efficiency with certified resistance to forced entry.

External Thermally Rated Steel Doors

Designed for exposed applications and may comply with:

• BS EN 14351-1 (external pedestrian doorsets)
• CE and/or UKCA marking requirements

Includes weather-resistant detailing and improved sealing systems.

Single and Double Leaf Insulated Doors

Available as:

• Single leaf personnel doors
• Double leaf doors for larger openings
• Thermal performance may vary depending on configuration.

Insulated steel doors can therefore be tailored to deliver basic insulation or certified thermal performance, while also incorporating fire resistance and security certification where required.

Insulated steel doors can be tailored to meet specific thermal performance targets, while also accommodating fire resistance, security certification, and architectural requirements.

Thermal Performance Levels

Doors can be specified to achieve:

• Standard insulated construction
• Thermally rated systems with U-values down to 1.5 W/m²K

Performance depends on core insulation type, frame design, and sealing system.

Fire-Rated Options (If Required)

Insulated steel doors can be combined with fire resistance:

• Internal doors tested to BS EN 1634-1
• External fire-rated doors compliant with BS EN 16034 (used with BS EN 14351-1)

Fire-rated insulated systems must remain within tested certification scope.

Security-Rated Configurations

Where required, doors may be specified to:

• PAS 24 enhanced security

Thermal performance and security hardware must be compatible within certified testing.

Door Configuration

• Single leaf doors
• Double leaf doors
• Made-to-measure sizing
• Side panels and overpanels (where certified)

Larger openings may require reinforced frames.

Glazing Options

Available with:

• Insulated glazing units (IGUs)
• Thermal glass systems
• Limited glazed panels within certified configurations

Glazing will affect overall U-value performance.

Hardware and Sealing Systems

Options may include:

• Multi-point locking for compression sealing
• High-security cylinders
• Perimeter weather seals
• Drop-down threshold seals
• Insulated thresholds

Seal design is critical to achieving stated U-values.

External Performance Enhancements

For externally exposed doors:

• Thermal breaks within frames
• Weather-resistant detailing
• Compliance with BS EN 14351-1
• CE/UKCA marking where required

Finish and Appearance

• Polyester powder-coated finishes
• Wide RAL colour selection
• Internal/external colour matching
• Textured or metallic finishes

Insulated steel doors can be customised to deliver improved energy efficiency while integrating fire resistance, security compliance, and external performance, provided all modifications remain within certified test evidence.

Insulated steel doors are specified wherever thermal efficiency, durability, and structural strength are required. They are commonly used in both commercial and industrial environments where controlling heat transfer is important.

External Personnel Doors

Installed on:

• Warehouses
• Industrial units
• Commercial buildings
• Service yards

Thermally rated doors help reduce heat loss and improve overall building energy performance.

Plant Rooms and Energy Centres

Used where:

• Heating systems
• Mechanical equipment
• Electrical infrastructure are located in external or semi exposed environments.

Insulated doors help maintain internal temperatures and protect equipment.

Office and Commercial Buildings

Specified for:

• Rear service doors
• Fire escape doors
• Secondary access points

Thermally rated options support compliance with energy efficiency requirements.

Residential Developments

Used in:

• Communal entrances
• Plant enclosures
• Bin stores
• Utility rooms

Where required, insulated doors can also meet PAS 24 security standards.

Fire Rated External Applications

Thermally rated fire doors are commonly installed in:

• Compartment walls
• Protected corridors
• External escape routes

Combining fire resistance with improved thermal insulation.

Industrial and Manufacturing Facilities

Installed between:

• Heated office spaces and factory floors
• Temperature controlled storage areas
• Loading bays and internal corridors

Helps reduce energy costs and maintain controlled environments.Insulated steel doors are selected wherever buildings require improved thermal performance alongside structural durability, and can also incorporate fire resistance and security certification where necessary.

Insulated steel doors are designed to improve thermal efficiency while maintaining the strength, durability, and compliance performance expected from a steel door set.

Improved Thermal Performance

Available as thermally rated systems with U-values as low as 1.5 W/m²K.

Benefit: Reduces heat loss, improves energy efficiency, and helps support compliance with building energy requirements.

High-Density Insulated Core

Constructed with insulated cores and thermally broken frames (where specified).

Benefit: Minimises heat transfer while retaining structural strength and impact resistance.

Weather Resistant Construction

Incorporates:

• Perimeter weather seals
• Insulated thresholds
• Compression sealing systems

Benefit: Reduces drafts, prevents water ingress, and maintains internal temperature control.

Fire Rated Options

Available as fire-tested door sets:

• Internal doors tested to BS EN 1634-1
• External fire-rated doors compliant with BS EN 16034

Benefit: Provides compartmentation and fire protection alongside thermal performance.

Security Rated Configurations

Can be specified to PAS 24 where enhanced security is required.

Benefit: Combines energy efficiency with certified resistance to forced entry.

Flexible Configurations

Available as:

• Single leaf doors
• Double leaf doors
• Glazed options (within certified scope)

Benefit: Adaptable to a wide range of building layouts and requirements.

Durable Steel Construction

Reinforced steel leaf and frame design.

Benefit: Long service life, low maintenance, and suitability for high-traffic environments.

Long Term Cost Savings

Improved insulation reduces heating and cooling demand.

Benefit: Lower operational energy costs over the life of the building.Insulated steel doors provide a practical solution where energy efficiency, fire resistance, security, and durability must be delivered within a single, high-performance door system.

Insulated steel doors must comply with relevant thermal performance, fire safety, security, escape, and external product standards, depending on their application within the building.

Thermal Performance Standards

Where a U-value is specified, thermally rated steel doors are assessed in accordance with:

• BS EN ISO10077-1 / 10077-2 – Thermal performance of doors and windows
• Declared U-value (W/m²K) for the complete door set

For externally installed doors, compliance may contribute toward meeting requirements under:

• Approved Document L (Conservation of Fuel and Power)

The declared U-value must relate to the tested or calculated complete door set.

External Door Compliance

Externally installed insulated steel doors must comply with:

• BS EN 14351-1 – External pedestrian doorsets
• CE and/or UKCA marking
• Declaration of Performance (DoP)

This covers weather resistance, wind load, air permeability, and water tightness.

Fire Resistance (If Fire-Rated)

Where insulated doors are also fire-rated:

• Internal doors must be tested to BS EN 1634-1
• External fire doors must comply with BS EN 16034 (used with BS EN 14351-1)

Fire-rated insulated doors must be installed as complete certified assemblies.

Security Certification (If Specified)

Where enhanced security is required:

• PAS 24 – Enhanced residential security

Security performance must apply to the complete insulated door set.

Emergency Escape Compliance (If Applicable)

If the door forms part of an escape route:

• Panic hardware must comply with BS EN 1125Emergency exit hardware must comply with BS EN 179
• Doors must allow immediate internal egress
• Thermal seals must not obstruct safe escape.

Accessibility Requirements

Where installed on accessible routes, doors must align with:

• Approved Document M (Access to and Use of Buildings)

This may affect clear opening widths, threshold heights, and hardware usability.

Installation Compliance

To maintain declared performance:

• Installation must follow manufacturer instructions
• Correct sealing and thermal detailing must be applied
• No unauthorised hardware substitutions
• Fire stopping must be used where fire-rated

When properly specified and installed, insulated steel doors can meet UK thermal performance standards, fire regulations, external product compliance, and security requirements, ensuring both energy efficiency and regulatory safety compliance.

Insulated steel doors must be installed correctly to achieve their declared thermal performance (U-value), and where applicable, to maintain fire, security, and external product certification. Poor sealing or incorrect fixing can significantly reduce insulation performance.

Installation Requirements

Structural Frame Installation

• Frame must be securely fixed into structural substrate (masonry, concrete, or steel)
• Frame must be square, plumb, and level
• Correct fixing centres must be used
• Gaps between frame and wall must be properly sealed

Incorrect installation can create thermal bridging and reduce performance.

Thermal Detailing

To achieve stated U-values:

• Perimeter compression seals must be fitted correctly
• Insulated thresholds must be installed accurately
• Thermal breaks within the frame must not be compromised
• No excessive gaps between leaf and frame
• Proper sealing is critical to preventing heat loss and air leakage.

Door Alignment and Hardware

• Hinges must be correctly positioned and load-rated
• Door must close fully and latch securely
• Multi-point locking (if fitted) must compress seals evenly
• Drop-down threshold seals must deploy correctly (if specified)

Consistent seal compression ensures optimal thermal performance.

Fire Rated Installation (If Applicable)

Where insulated doors are also fire-rated:

• Internal doors must comply with BS EN 1634-1
• External fire doors must comply with BS EN 16034
• Intumescent seals must be correctly fitted
• Approved fire-stopping materials must be used around the frame

Improper installation may invalidate fire certification.

Security Rated Installation (If Applicable)

For PAS 24 doors:

• Fixings must match tested detail
• Hardware must match certified configuration
• No unauthorised modifications

External Installation

For external doors:

• Weather seals must be correctly installed
• Drainage and threshold detailing must prevent water ingress
• Powder-coated finish protected during installation
• Installation must align with BS EN 14351-1 requirements

Supply Only Considerations

If supplied only:

• Installer assumes responsibility for maintaining thermal, fire, or security certification
• Installation must follow technical drawings precisely
• Incorrect fitting may invalidate declared U-values

Professional installation is recommended for certified systems.

Maintenance Requirements

Regular inspection ensures continued thermal efficiency and safe operation.

Routine Inspection (Recommended Annually or Quarterly in Commercial Settings)

Check for:

• Smooth operation
• Proper latch engagement
• Secure hinge fixings
• Frame stability
• Seal integrity
• Threshold condition

Seal and Threshold Maintenance

• Inspect perimeter weather seals for wear
• Ensure drop-down seals operate correctly
• Replace damaged seals promptly
• Keep threshold area clear of debris
• Damaged seals will reduce thermal performance.

Hardware Maintenance

• Lubricate hinges and locks
• Adjust closers where fitted
• Check multi-point locking systems
• Test panic hardware (if installed)

Fire Door Maintenance (If Fire-Rated)

• Inspect intumescent seals
• Confirm self-closing action
• Ensure no unauthorised alterations

External Door Maintenance

• Inspect weather seals
• Check for corrosion
• Maintain powder coated finish
• Ensure drainage remains clear

When correctly installed and maintained, insulated steel doors deliver long-term energy efficiency, durability, and compliance with thermal, fire, and security performance standards.

(Indicative UK pricing – excludes VAT unless stated)The cost of insulated steel doors depends on the required thermal performance (U-value), whether fire or security certification is needed, door size, configuration, and installation complexity.

Standard Insulated Steel Doors

Basic insulated steel doors for improved thermal performance over non-insulated models.

• Supply only: From £850 – £1,500
• Supplied and installed: From £1,700 – £2,800

Suitable for plant rooms, warehouses, and service areas.

Thermally Rated Steel Doors (U-values down to 1.5 W/m²K)

Engineered for measurable thermal performance.

• Supply only: From £1,400 – £2,500
• Supplied and installed: From £2,800 – £4,500

Commonly specified for external personnel doors and commercial buildings.

Thermally Rated Fire Steel Doors

Internal doors tested to BS EN 1634-1, external doors compliant with BS EN 16034.

• Supply only: From £1,800 – £3,500+
• Supplied and installed: From £3,500 – £6,500+

Fire rating and thermal performance combined increases cost.

Thermally Rated PAS 24 Steel Doors

Thermal insulation combined with enhanced residential security.

• Supply only: From £2,000 – £3,500
• Supplied and installed: From £3,800 – £6,500

Often specified for apartment blocks and residential developments.

Double Leaf Insulated Steel Doors

• Supply only: From £1,800 – £3,800+
• Supplied and installed: From £3,500 – £7,000+

Pricing varies depending on performance level and size.

Additional Cost Considerations

• Insulated glazing units
• Multi-point locking systems
• Access control integration
• Powder-coated colour upgrades
• Structural alterations
• Site access and installation complexity

What Affects Final Pricing

• Required U-value (standard insulated vs thermally rated 1.5 W/m²K)
• Fire rating (FD60 / FD120)
• Security certification (PAS 24)
• Door size and configuration
• External performance compliance
• Installation access and preparation

Getting an Accurate Quote

Because thermal performance depends on the complete installed door set, accurate opening sizes and required U-values are essential. A site survey is recommended to confirm specification, ensure compliance with Approved Document L (where applicable), and provide accurate installation pricing.