Overview
EN ISO 11855-5:2021/A1:2023 is the CEN-endorsed amendment to Part 5 of ISO 11855, which covers installation requirements for embedded radiant heating and cooling systems (floor, wall and ceiling-integrated systems). This amendment (A1) updates installation illustrations, joint typologies and a table entry related to thermal insulation geometry. It was approved by CEN in May 2023 and adopted as a national standard across CEN members.
Key topics and technical requirements
- System layers and components - the amendment clarifies the position and naming of construction layers used in embedded radiant systems:
- Thermal insulation layer
- Protection layer
- Thermal diffusion layer
- Surface layer
- Structural layer
- Pipes or electric cables
- Joints - definitions and placement
- Construction joints: structural joints through the full element thickness (wall, floor, ceiling), including reinforcement.
- Expansion (movement) joints: cross the full screed thickness to accommodate dimensional changes mainly due to temperature.
- Contraction joints: guided break lines that interrupt part of the screed thickness; the cut depth shall not exceed 1/3 of the uniform screed layer.
- For heating screeds of type I, movement and perimeter joints may be crossed only by connecting pipes at a single level; these connecting pipes must be covered with a flexible insulation tube approximately 0.3 m long.
- Insulation geometry update
- Amendment A1 modifies a Table 1 entry specifying the thickness of thermal insulation in type II systems measured from the outward edge of the insulation to the inward edge of the pipes (see referenced figure).
- Illustration updates
- Figure 1 keys and joint typologies were revised to align installation guidance with the updated terminology and dimensional rules.
Practical applications and users
This amendment is relevant for professionals involved in designing, specifying and installing embedded radiant systems:
- HVAC and building services engineers
- Architects and façade/structure designers
- Mechanical contractors and installers
- Flooring and screed subcontractors
- Manufacturers of radiant heating/cooling components
- Standards bodies and compliance officers
Practical uses include setting pipe routing and depth, specifying insulation thickness and joint detailing to prevent thermal stress, and ensuring correct layering for effective heat diffusion and long-term durability.
Related standards
- ISO 11855 series (Parts 1–6) - overarching design, performance and testing guidance for embedded radiant heating and cooling systems.
- National and regional building and HVAC codes referenced by EN/CEN members.
Keywords: EN ISO 11855-5:2021/A1:2023, embedded radiant heating and cooling, installation requirements, radiant floor heating, thermal insulation, expansion joints, contraction joints, heating screed.
