Spreader plates
AD-PLATE
A lightweight heating layer beneath a separate timber floor deck.
- Heating layer
- Aluminium plates holding the pipe
- Choose when
- You want a dry system without screed
- Plan ahead
- Plate fit, joist access and deck contact
Water underfloor heating by floor construction
Underfloor Heating for Timber Floors
Compare water heating systems for suspended timber and joisted floors.
Choose lightweight spreader plates, a grooved chipboard deck or a designed dry-mix infill. The best fit depends on your joists, floor access and the layers above the heating pipe.
Choose How the Heating Fits Your Floor
Construction at a glance
What Changes Between the Systems?
The key difference is where the heating sits and what needs to go above it.
| Comparison criteria | AD-PLATE | AD-CHIPBOARD | AD-DRY |
|---|---|---|---|
| Floor deck | Separate deck above the plates | Grooved chipboard forms the heating deck | Separate deck above the infill |
| Layers above the heating | Specified deck and floor finish | Protective flooring-grade layer, then floor finish | Specified deck and floor finish |
| Added screed | None | None | Specified dry-mix infill |
| Before choosing | Check plate size, joist layout and contact with the deck | Allow for the protective layer above the 22mm board | Confirm the full load, insulation support and infill design |
| Explore the solution | View AD-PLATE | View AD-CHIPBOARD | View AD-DRY |
AD-PLATE
- Floor deck
- Separate deck above the plates
- Layers above the heating
- Specified deck and floor finish
- Added screed
- None
- Before choosing
- Check plate size, joist layout and contact with the deck
AD-CHIPBOARD
- Floor deck
- Grooved chipboard forms the heating deck
- Layers above the heating
- Protective flooring-grade layer, then floor finish
- Added screed
- None
- Before choosing
- Allow for the protective layer above the 22mm board
AD-DRY
- Floor deck
- Separate deck above the infill
- Layers above the heating
- Specified deck and floor finish
- Added screed
- Specified dry-mix infill
- Before choosing
- Confirm the full load, insulation support and infill design
Before you order
Check the Floor Before Choosing
Send us your room dimensions, joist layout and proposed floor finish. These four checks help narrow down the right system.
- Structure and access: joist condition, spacing, load capacity and the work needed to reach the floor zone.
- Insulation: its type, thickness and support beneath the heating layer.
- Heating design: room heat loss, heat-source temperature, manifold position and pipe circuits.
- Finished floor: deck layers, floor-covering limits and any additional preparation or controls.
Plan the Complete Build-Up
Plan from the structure upwards. The selected system determines the deck, preparation and final floor level.
- Confirm the joists and supports; any drilling or notching must follow the structural design.
- Specify and support insulation beneath the heating layer.
- Fit the selected plates, grooved deck or designed infill and lay the pipe circuits.
- Connect, fill and pressure-test before closing or covering the floor.
- Install the required deck or protective layer, preparation and compatible floor finish.
Suspended timber floor advice
Frequently Asked Questions
Practical answers about floor access, insulation, system choice and finishes.
Can water underfloor heating work in a suspended timber floor?
Yes, where the structure, insulation and finished-floor build-up are suitable. Spreader plates, a grooved chipboard deck or a designed between-joist infill provide different ways of incorporating the heating.
How do I choose between the three systems?
Consider AD-PLATE for a lightweight heating layer below a separate deck, AD-CHIPBOARD when fitting or replacing the deck, and AD-DRY where a supported infill with additional thermal mass is part of the design. Joist layout, heat loss and floor finish should guide the final choice.
Can I keep the existing floorboards?
If the existing structural deck is sound and will stay in place, an overlay system may be a better starting point. If you want heating within the joist zone, access and the installation method need checking before you choose.
Do I need insulation between the joists?
Suitable insulation below the heating layer helps limit downward heat loss. The required material, thickness, support and acoustic performance depend on the floor design.
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Will underfloor heating raise the floor level?
That depends on the complete construction. AD-PLATE and AD-DRY sit below a separate floor deck. AD-CHIPBOARD uses a 22mm grooved deck plus a protective upper layer and floor finish. Check the final level at doorways, stairs and adjoining rooms.
Can joists be drilled or notched for the pipe?
Pipe routes must suit the structure. Do not drill or notch joists without confirming the permitted locations and dimensions for the joist type and structural design. Include these routes in the plan before installation.
Which floor finishes can I use?
Compatible engineered wood, tiles, vinyl and carpet may be used with the correct floor build-up. Follow the flooring manufacturer’s temperature and thermal-resistance limits, and specify any necessary deck, underlay or preparation layers.
Can these systems work with a heat pump?
The room heat loss and output through the proposed deck and floor finish must be checked at the heat pump’s design water temperature. Send us those details so the heating system can be specified around the project.