How to Bridge a Cavity Wall below a Door Threshold without creating a Thermal Bridge
Cavity-wall construction creates a particular challenge where a door, sliding door or large glazed element needs to be supported across the cavity.
TRIOTHERM+ Insulated Door Upstands
Structural Support Meets Thermal Insulation
A load-bearing, thermally insulating solution for entrance doors, sliding doors and floor-to-ceiling glazing.
One Component. Two Essential Functions.
TRIOTHERM+ combines structural support with thermal insulation at the critical junction between the door threshold and the building structure.
Load-Bearing Support
A stable, engineered base beneath doors and glazed elements.
Reduced Thermal Bridging
Helps maintain insulation continuity at floor-level connections.
Flexible Installation
Adaptable to different door systems, building methods and threshold heights.
Designed for Modern Building Envelopes
The position of doors and glazing within the building envelope plays an important role in thermal performance. TRIOTHERM+ allows load-bearing threshold support to be integrated with the surrounding insulation, helping designers address thermal bridging without relying on conventional masonry or concrete supports.
Technical Performance & Design
Why Specify a TRIOTHERM+ Door Upstand?
A door threshold must do more than support the frame. It must accommodate structural loads, maintain thermal continuity and integrate with the building's moisture protection strategy.
The Threshold Is a Critical Building Junction
TRIOTHERM+ provides an engineered alternative to conventional masonry or concrete support details, combining load-bearing performance with low thermal conductivity.
Documented Material Performance
0.0374
W/(m·K)
Thermal conductivity
λ10
1,260
kg/dm²
Load-bearing capacity
at max. 2% deformation
≤ 0.5 vol.%
Water absorption after 28 days
of immersion
Key Considerations for Designers
Effective door threshold design requires the coordination of thermal performance, structural support, moisture protection and installation details. TRIOTHERM+ provides a thermally insulating, load-bearing support as part of the overall building envelope design.
01
Thermal Bridge Reduction
Maintain insulation continuity beneath doors and glazing, helping to reduce heat flow through the threshold junction and supporting the building's overall thermal performance.
02
Structural Load Transfer
Transfer vertical loads from door and glazing systems through a properly designed support and fixing arrangement into the building structure.
03
Moisture Protection
Integrate the door upstand with appropriate damp-proof courses (DPC), waterproofing and drainage details to protect the complete threshold connection.
04
System Integration
Coordinate threshold height, door frame position, floor construction and fixing components early in the design process to achieve a practical installation detail.
Structural suitability, load transfer, fixing arrangements and waterproofing must be assessed for each project. Product performance and supporting evidence are available in our Technical Documentation .
Knowledge & Practical Experience
Technical Insights & Practical Guidance
Explore technical articles, construction details and practical experience relating to insulated door thresholds, thermal bridging and building envelope design. Our Insights cover product applications, structural considerations, moisture protection and common challenges encountered in modern construction.
Below you will find our latest articles and technical observations.
Level-Access Door Thresholds: What Must Be Coordinated Before the Upstand Is Ordered
Level-access and low-threshold doors can provide a clean and accessible transition between inside and outside.
Insulated Door Upstands: Why the Complete System Matters
Insulated door upstands are increasingly being used to reduce thermal bridging below entrance doors, sliding doors and large glazed elements.
225mm Door Upstand Height? Why the 230mm Standard Height Can Be the Safer Choice
We regularly get questions about a 225 mm insulated door upstand.
How Much Weight Can a Triotherm+ Door Upstand Carry?
One of the questions we are asked most frequently is:
Installation Insights for a Sliding Door Upstand
We’re excited to share more details about the installation process of a Triotherm insulated door upstand for a sliding door, recently used in our own retrofit project. Since most sliding doors come with a frame depth exceeding 125mm, you may need to extend the standard Triotherm+ profile by incorporating a structural insulation board upright or even by using two rows of Triotherm+ for optimal results.
Positioning of Triotherm Door Upstands
Proper positioning of Triotherm Door Upstands is crucial to ensure optimal thermal performance while minimizing disruptions to subsequent trades. Ideally, the upstand should align closely with the top of the door or window frame. The exact placement within the door or window opening will depend on the specific wall construction. In general, the door upstand should be positioned to maintain continuity with the building’s insulation layer for optimal performance. Below, you'll find guidance tailored to the most common wall systems.
Required Dimensions for Triotherm Door Upstands
In response to frequent questions about the dimensions required for Triotherm door upstands, we have put together the following guidance.
Triotherm from an Environmental Perspective
Every construction material has an environmental impact. The important question is not whether a product is completely impact-free, but how its environmental characteristics relate to its performance, durability and function within the building.
Triotherm Door Upstands - To Be Without DPC?
We frequently receive questions about the correct waterproofing approach for Triotherm door upstands.
Available Standard Dimensions for Triotherm Door Upstands
Triotherm door upstands can be configured in a wide range of dimensions to suit different door frames, threshold details and floor build-ups.
Triotherm Insulated Door Upstands: A Customisable Solution
Triotherm insulated door upstands can be configured to suit a wide range of door, window and threshold details.