Installed Between the Joists
The heating circuits sit within the floor zone rather than forming a separate overlay above the structural deck.
Water underfloor heating solution
AD-DRY Between-Joist Dry-Screed System
A thermal-mass warm-water system designed for suitable suspended timber and battened floors.
AD-DRY positions water underfloor heating pipe within rigid insulation between the joists before the specified dry-mix screed is installed around the circuits. It brings thermal mass into a timber-floor construction, but the added load and complete structural arrangement must be verified before installation.
Why choose AD-DRY?
Thermal Mass Within a Timber Floor Construction
AD-DRY combines between-joist pipework with a specified dry-mix screed layer when a structural timber floor can accommodate the additional load.
Dry-Mix Screed Adds Thermal Mass
The specified screed surrounds the pipe and provides a heat-distributing layer within the timber construction.
Retains a Conventional Floor Surface
Once the designed joist infill and structural deck are complete, compatible finishes can follow the approved timber-floor build-up.
The system behind the solution
Plan Your AD-DRY System
A between-joist dry-screed system designed around the structure of your timber floor. Our team can help assess the load and plan the build-up.
Designed around your timber floor
The joists, support and dry-screed load must be checked for each project.
Plan with our team
Check the floor structure first
AD-DRY adds thermal mass between joists. The joist capacity, insulation support, pipe layout and complete floor construction need a project-specific design.
- Check the existing floor construction
- Plan pipe routes and controls
- Confirm the complete floor build-up
Send us your dimensions or plans and our team can help with the design.
Designed between-joist installation
How AD-DRY Is Installed
The structural support, insulation, pipe layout and dry-screed specification must be coordinated before the floor is closed.
- 1Confirm the heat loss, joist arrangement, manifold position, circuit design and intended floor finish
- 2Have the existing floor structure and proposed additional load assessed where required
- 3Install and support the specified rigid PIR insulation at the designed level between the joists
- 4Add any membrane required by the insulation and dry-screed specification
- 5Fix the heating pipe using the approved clip or rail arrangement and connect the circuits
- 6Fill and pressure-test the pipework before installing the specified dry-mix screed
- 7Complete the structural deck, curing or commissioning sequence and compatible final floor finish
Designed to add thermal mass
Why the Dry-Screed Layer Matters
The dry-mix screed surrounds the pipe and changes how the timber floor stores and releases heat.
- The screed increases contact around the pipe compared with a fully open floor void
- Thermal mass helps distribute heat beneath the deck and final floor finish
- Supported insulation contains the screed and limits downward heat loss
- The added mass changes the floor loading and must be allowed for structurally
- The response time will differ from lightweight aluminium-plate timber systems
Plan the complete installation
Where AD-DRY Works Best
AD-DRY is for timber-floor projects that can accept the designed between-joist screed load and where additional thermal mass is desirable.
- Structurally suitable suspended timber floors
- Suitable battened floor constructions with adequate support
- Projects where the pipe and screed can be installed between the joists
- Floors using supported rigid PIR insulation beneath the heating layer
- Installations with access to coordinate the pipe routes, manifold connections and floor deck
Typical AD-DRY Floor Build-Up
The precise supports, membrane, screed depth and deck depend on the floor structure and specified products. Use the project design and current installation instructions.
- 1Structurally suitable timber joists or battens
- 2Supported rigid PIR insulation between the joists
- 3Specified membrane where required
- 4Water underfloor heating pipe fixed by the approved clip or rail method
- 5Specified dry-mix screed around and above the pipe
- 6Structural floor deck and approved preparation layer
- 7Compatible final floor finish
- Between joists
- Heating-layer position
- Rigid PIR
- Typical insulation support
- Dry mix
- Heat-distributing screed
- ≈20kg/m²
- Nominal added load to verify
AD-DRY project advice
Frequently Asked Questions
Clear answers about dry screed, structural loading, insulation and planning an AD-DRY timber-floor installation.
What is the AD-DRY system?
AD-DRY is a warm-water underfloor heating construction for suitable timber floors. Pipe is fixed over supported insulation between the joists and surrounded by a specified dry-mix screed.
How is AD-DRY different from AD-PLATE?
AD-DRY uses a dry-mix screed to add thermal mass around the pipe. AD-PLATE uses lightweight aluminium spreader plates and does not introduce a traditional screed layer into the timber floor.
How much additional weight does AD-DRY add?
The existing system information identifies approximately 20kg/m² for the dry-screed layer. The complete load and the floor’s capacity must be verified for the actual specification.
Does AD-DRY require rigid insulation?
The current construction uses supported rigid PIR insulation beneath the heating layer. Its thickness, support and any membrane requirements must follow the project design.
View all AD-DRY questions Show fewer questions
Can AD-DRY be installed in any suspended timber floor?
No. The joists, supports, available depth, installation access and added load must all suit the proposed construction. Structural advice may be required for an existing floor.
Which floor finishes can be used over AD-DRY?
Compatible tile, engineered wood, vinyl or carpet finishes can be used when the structural deck and any required preparation layer are approved for the covering and heating system.
Does AD-DRY respond like a lightweight timber system?
Not exactly. The dry-screed layer adds thermal mass, so the system is likely to warm and cool more gradually than a lightweight plate construction. The controls should be set for the completed floor.
How is an AD-DRY project designed?
Provide the joist layout, heated area, structural information, heat loss, heat source and intended finish. The design should confirm insulation, pipe routes, screed construction, circuits, manifold and controls.