The main advantage of a Triotherm insulated door upstand is that it combines structural support with thermal insulation at one of the most critical junctions in the building envelope.
Door thresholds, sliding doors and floor-to-ceiling windows often interrupt the insulation layer at floor level. If the support beneath the frame is highly conductive, this can create a significant thermal bridge.
Triotherm+ provides a structural thermal solution that supports the door or window frame while helping to maintain continuity of the insulation layer.
Thermal overlays of two different patio doors. The left one has a massive thermal bridge at floor level, due to a missing Triotherm insulated door upstand.
Improved Thermal Performance
Traditional structural upstands made from concrete, masonry or other highly conductive materials can create a significant thermal bridge beneath the door frame.
Triotherm+ has a much lower thermal conductivity and can therefore substantially reduce heat flow through the threshold support.
This helps maintain a more continuous thermal envelope around doors and floor-to-ceiling windows.
Reduced Thermal Bridging
Thermal bridging occurs where a conductive material interrupts the insulation layer and creates an easier path for heat to escape.
At door thresholds, this can lead to:
- increased heat loss
- lower internal surface temperatures
- increased risk of surface condensation
- reduced overall building-envelope performance
A properly designed Triotherm+ upstand reduces this thermal bridge by replacing a highly conductive structural support with a structural insulation material.
Structural Support
Triotherm+ is not simply an insulation product.
It is designed to transfer loads from the door or window frame into the structural substrate below.
This makes it suitable for applications such as:
- entrance doors
- sliding doors
- lift-and-slide systems
- bi-fold doors
- floor-to-ceiling windows
- other large glazed elements
The suitability of a specific installation depends on the complete load path, including the frame, support points, upstand dimensions, substrate and fixing arrangement.
Moisture Resistance
Triotherm+ is manufactured from high-density EPS and has very low water absorption.
The published technical data states a water absorption of:
≤ 0.5 vol.% after 28 days of full immersion
This makes the material well suited to threshold areas where moisture resistance is an important consideration.
The complete waterproofing detail must, however, still be designed and sealed correctly.
Simplified Threshold Detailing
A Triotherm+ upstand can simplify the junction between:
Floor insulation → Door upstand → Door or window frame
This can make it easier to coordinate:
- structural support
- thermal insulation
- threshold height
- waterproofing
- airtightness
- internal floor finishes
- external paving or drainage
Using one structural thermal component in place of several different materials can also simplify installation and reduce the number of interfaces within the detail.
Suitable for Different Wall and Floor Constructions
Triotherm+ can be incorporated into a wide range of construction types, including:
- cavity-wall construction
- external wall insulation systems
- timber frame
- ICF
- monolithic masonry
- retrofit applications
The correct position of the upstand depends on the wall construction and the location of the building’s insulation layer.
The aim should always be to maintain continuity between the floor insulation, wall insulation and door or window frame.
Why This Matters
The threshold beneath a large door or glazed element may extend for several metres.
Even a relatively small thermal weakness can therefore become significant when repeated across the full width of the opening.
A structural thermal upstand helps address this junction without compromising the support required by the frame.
The Important Point
Triotherm+ should not be viewed simply as an alternative material for forming a door upstand.
Its main advantage is that it combines:
Structural support + thermal insulation + moisture resistance
in one system.
This allows the threshold detail to be designed with both structural and thermal performance in mind.