Name: ThermRite 6mm Fibre Cement Cover Boards for HeatBoard One Panels
Brand: AIZO Quality Heating
SKU: thermrite-6mm-fibre-cement-cover-boards-for-heatboard-one-panels
Availability: InStock

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ThermRite 6mm Fibre Cement Cover Boards for HeatBoard One Panels

The ThermRite 6mm Fibre Cement Cover Board is a high-strength, water-resistant overlay board designed to be laid over HeatBoard ONE (and Easy Lay) routed chipboard underfloor heating panels. It serves two distinct purposes: it provides the tile-ready substrate needed for ceramic and porcelain tile installations — tile adhesive cannot bond reliably to chipboard — and it adds thermal mass to the floor build-up, acting as what ThermRite describes as a 'heat battery' that absorbs, stores and slowly releases heat for a more even and consistent floor surface temperature. At 1,200 × 600mm and 6mm thick, each board matches the footprint of a HeatBoard ONE 1200mm panel, covers 0.72m², and is screw-fixed to the chipboard using ThermRite 5 × 25mm fixing screws (sold separately). The result is a 28mm total build-up above the joist that is structurally sound, tile-ready and optimised for even heat distribution.

6mm

Thickness

1200×600

Dimensions

Tile-Ready

Ceramic & Porcelain

Thermal

Mass Layer

Water-

Resistant

0.72m²

Per Board

HeatBoard Range — Where This Product Fits

System	Build-Up	Foil/Plate	Key Difference	Best For
HeatBoard ONE	22mm	No foil	Single panel, standard output	Cost-efficient installs, budget renovations
HeatBoard ONE PLUS	22mm	Full aluminium foil	Single panel, higher output	Faster warm-up, better output from same pipe
HeatBoard Fusion	28mm	Foil-backed 6mm cover	Two-part structural system	Suspended floors needing deck + heating
HeatBoard ULTRA	22mm	Aluminium diff. plates	Maximum output, single panel	High-demand rooms, large areas, heat pumps
+ ThermRite 6mm Cement Board ★	+6mm	N/A (overlay only)	Overlay to add tile-readiness & thermal mass	Tile finishes over ONE or ULTRA

★ This product. All chipboard systems use 12mm pipe at 150mm centres on joists up to 600mm.

ℹ Installation: Lay the cement board over the routed chipboard once the pipe is fully installed and pressure-tested. Fix with ThermRite 5×25mm screws — never fix through pipe routes. Apply tile adhesive to the cement board surface in the normal way. Score and snap for straight cuts; use an appropriate saw for shaped cuts.

Key Features

Enables Ceramic and Porcelain Tiles Directly Over HeatBoard ONE

The ThermRite 6mm fibre cement board is the correct overlay for laying ceramic or porcelain tiles directly over HeatBoard ONE (and Easy Lay) routed chipboard panels. Tile adhesive does not bond well to chipboard — chipboard flexes under load, absorbs moisture and provides an inadequate substrate for tile installations. The cement board eliminates all three problems: it is rigid, dimensionally stable and water-resistant, giving tile adhesive a proper keying surface that will not delaminate or crack over time with UFH thermal cycling.

Tile-ready surfaceCeramic & porcelain directReplaces plywood underlay

High-Strength Fibre Cement — Rigid, Water-Resistant, Dimensionally Stable

Fibre cement board is manufactured from a mix of Portland cement, cellulose fibres and aggregates, pressed into a dense, homogeneous panel. The result is a material that is significantly stronger than plywood of the same thickness, completely water-resistant (it does not swell, warp or delaminate when wet), and dimensionally stable across temperature changes — an important property when boards sit directly above a heating pipe that cycles between ambient and ~45°C. It also resists mould, rot and insects — unlike timber-based substrates in damp locations.

Stronger than plywoodWater-resistantMould & rot resistant

Thermal Mass — Acts as a 'Heat Battery' for Improved System Efficiency

Fibre cement has a higher thermal mass than timber or insulation boards — it absorbs and stores heat energy before releasing it slowly and evenly upward. ThermRite describes this as the board acting as a 'heat battery': once the system reaches operating temperature, the cement board continues radiating heat into the room even during brief pauses in heating, smoothing out temperature fluctuations and reducing the frequency and duration of boiler or heat pump cycling. This is particularly beneficial with heat pump systems that prefer long, steady runs at low temperature rather than frequent on/off cycling.

Thermal mass'Heat battery' effectReduces cycling

Even Heat Distribution Across the Full Floor Area

The cement board conducts heat laterally as well as vertically. Heat rising from the pipe into the chipboard grooves spreads across the cement board before reaching the tile above, reducing the temperature differential between directly above a pipe and the mid-point between two pipes. The result is a more uniform surface temperature across the tiled floor — no detectable hot stripes over pipe runs, no cooler strips between them.

Even lateral heat spreadNo hot stripesUniform tile temperature

Strengthens the Routed Chipboard Carrier — Covers the Pipe Grooves

Once the 12mm pipe is laid in the HeatBoard ONE chipboard grooves, the exposed grooves leave the pipe partially unprotected. The cement board covers and seals the pipe grooves, protecting the pipe from point loads during tile installation and ongoing floor use, and preventing adhesives or grout from entering the groove cavities. It also stiffens the chipboard surface, improving the composite rigidity of the floor deck.

Covers pipe groovesProtects pipeStiffens deck

Screw-Fixed to the Chipboard — No Adhesive Required for Board Installation

The cement board is screwed down to the routed chipboard beneath using ThermRite 5 × 25mm fixing screws (sold separately as the RTCHIP-CB screw pack). Approximately 48 screws are required per 1,200 × 800mm cement board area. One box of 200 screws covers approximately 4m² of cement board. No adhesive is needed between the chipboard and cement board — screws alone provide the required bond. Tile adhesive is applied to the top surface of the cement board when tiling.

Screw-fixed5×25mm screws~48 screws per board

1,200 × 600mm Boards — Easy to Handle, Matches HeatBoard ONE Footprint

The cement board is the same 1,200 × 600mm footprint as the HeatBoard ONE (1200mm variant) for a direct one-for-one overlay without cutting. At 6mm thick, boards are light enough to carry and position single-handedly. They can be cut by scoring and snapping for straight cuts, or with a suitable saw for shaped cuts around pipe entries and obstacles.

1200×600mm0.72m² per boardScore and snap

Technical Specifications

Board
Material	High-strength fibre cement
Dimensions	1,200 × 600mm (0.72m² per board)
Thickness	6mm
Properties	Water-resistant, mould-resistant, dimensionally stable
Cutting Method	Score and snap (straight cuts); saw (shaped cuts)
Installation
Substrate	HeatBoard ONE or Easy Lay 22mm routed chipboard
Fixing Method	Screwed to chipboard (screws not included — sold separately)
Screw Specification	5 × 25mm (ThermRite RTCHIP-CB screw pack)
Screws Per Board	Approx. 48 per 1,200 × 800mm area
Screws Per Box (200 pack)	Covers approx. 4m²
Adhesive (board to chipboard)	Not required
Tile Adhesive	Applied to top surface of cement board in the normal way
System Build-Up with HeatBoard ONE
HeatBoard ONE chipboard	22mm
12mm pipe (in grooves)	Adds no height above board face
ThermRite 6mm cement board	6mm
Total above joist	28mm
Floor finish (tiles + adhesive)	Typically 15–25mm additional

Frequently Asked Questions

Do I need the cement board to tile over HeatBoard ONE?

Yes — for ceramic and porcelain tile installations, the cement board is necessary. Tile adhesive applied directly to chipboard is unreliable: chipboard absorbs moisture from the adhesive, swells unevenly and eventually debonds. The cement board provides the stable, water-resistant, non-absorbent surface that tile adhesive requires for a permanent bond, particularly where underfloor heating thermal cycling adds stress to the adhesive layer.

Can I use this board over HeatBoard ONE PLUS (foiled panels)?

Yes — the ThermRite 6mm cement board is compatible with HeatBoard ONE PLUS as well as the standard HeatBoard ONE. Where the ONE PLUS already has a foil layer, the cement board adds the tile-ready substrate and thermal mass benefits on top of the foil's heat-spreading function.

How many boards do I need?

Each board covers 0.72m². Measure the heated floor area, divide by 0.72, and round up to the nearest whole board. Add 5–10% for cuts and waste. The ThermRite fixing screw pack (200 screws) covers approximately 4m² — order one box per 4m² of cement board.

Does the cement board need to be jointed and taped?

For floor tile applications over HeatBoard ONE, jointing tape is not typically required between boards when the boards are screw-fixed to a stable chipboard base. The rigid chipboard substrate and tile adhesive bed provide the required continuity. For wet areas (showers, wet rooms), consult the system installation guide for whether additional waterproofing at board joints is required before tiling.

Can I use a different brand of 6mm cement board?

The ThermRite board is dimensionally matched to HeatBoard ONE panels (1,200 × 600mm footprint) and tested with the system. Alternative 6mm fibre cement boards of the same size and specification may be used, but compatibility and performance should be verified against the system design before substituting a non-ThermRite product.