The Unifloor Heat-Pak® Dual Board Overlay System is a fast-track, pre-fabricated subfloor solution engineered specifically for installation directly over all types of underfloor heating — including electric cable, mat, foil and film systems as well as hot-water (hydronic) UFH. Comprising a 3 mm MDF baseboard bonded to a 4 mm MDF top board with a factory-applied interactive contact adhesive, each pair of boards clicks together in a staggered overlap joint to produce a seamless, ghost-free surface for direct glue-down of LVT, vinyl sheet, linoleum, rubber, cork and carpet. At just 7 mm total thickness and with an ultra-low TOG rating of 0.7, Heat-Pak® keeps your heat energy flowing freely upward — with no smoothing compound, no drying time and no wet trades required.
7 mm
Total Thickness
(3 mm base + 4 mm top)
TOG 0.7
Thermal Resistance
Ultra-Low Rating
2.88 m²
Coverage per Pack
600×1200
Board Dimensions (mm)
±1.5 mm tolerance
0 min
Setting / Drying Time
Dry-Fit System
MDF
High-Quality Core
FSC Certified
ⓘ Dry Process — No Smoothing Compound Needed
Heat-Pak® is an entirely dry installation system. Unlike smoothing compounds or self-levelling screeds, there is no curing or setting time. Your chosen floor covering can be glued down immediately after the boards are laid, reducing project time significantly on both domestic and commercial jobs.
ⓘ Overlap Joint Technology — Eliminates Joint Ghosting
The twin-layer overlap joint configuration staggers the board edges so that no joint lines telegraph through high-sheen finishes such as polished LVT or sheet vinyl. This is a critical advantage over single-board underlays and traditional ply overlays where joint lines commonly reflect through gloss floor surfaces.
⚠ Electric UFH: Pair with Heat-Blok® Below the Heating Element
For electric cable, mat, foil or film underfloor heating systems, Unifloor recommends laying Heat-Blok® (6 mm, TOG 1.9) as a thermal insulation layer directly beneath the heating element. Heat-Pak® is then installed above the element (TOG 0.7 above, TOG 1.9 below), ensuring heat is directed upward rather than lost into the subfloor. This combination also achieves up to 21 dB ΔLw impact sound reduction with glued linoleum, per EN-ISO 10140-3:2010.
⚠ Floor Cooling Systems
When Heat-Pak® is used over a floor cooling system (rather than floor heating), a moisture monitoring system is required beneath the boards to prevent condensation damage. Consult your UFH supplier for appropriate moisture management products before installation.
Why Heat-Pak® outperforms traditional subfloor methods:
🔥 Ultra-Low TOG 0.7 — Maximum Heat Transfer
An MDF core has inherently low thermal mass compared to cement-based levelling compounds. At TOG 0.7, Heat-Pak® allows heat energy to pass through rapidly, giving you a fast warm-up time and no energy wastage trapped below the floor surface. Conventional smoothing compounds can have significantly higher thermal resistance, throttling UFH output.
🛠 Pre-Applied Adhesive — No Separate Bonding Product
Both the 3 mm baseboard and 4 mm topboard arrive from the factory already coated with a special interactive contact adhesive. Simply press the two layers together under the weight of installation and the adhesive creates a strong, permanent, full-surface bond. No additional glue or bonding agent is required between the two MDF layers — reducing materials cost and on-site consumables.
⚡ Compatible with All UFH Types
Heat-Pak® is confirmed compatible with electric cable systems, electric mat systems, electric foil and film systems, and hot-water (hydronic) underfloor heating. The boards are simply placed over the heating element — the low-profile 7 mm build-up means minimal floor level change at door thresholds and room transitions compared to screeded systems.
🏠 Protects Your Heating System and Floor Covering
Once laid, the MDF panel stack encapsulates and mechanically protects the entire heating element from foot traffic, tool drops and compressive loads during flooring installation above. At the same time, the smooth, dimensionally stable surface ensures your LVT, vinyl, linoleum or carpet adheres evenly — with no undulations, ridges or hot-spot cracking in the finish.
📋 Overlap Joint — Ghost-Free Seamless Finish
The dual-board offset layout means baseboard joints and topboard joints never align in the same location. This staggered configuration distributes structural load evenly and prevents joint-line reflection (ghosting) through high-gloss or thin resilient floor coverings — a common complaint with single-layer plywood or OSB overlays and with hardboard pinned directly to joists.
✅ Fast-Track Installation — Lay and Cover in One Visit
Because Heat-Pak® is a completely dry, pre-fabricated system, there is no compound mixing, no waiting for leveller to cure and no risk of contaminating the heating element with wet chemistry. The boards are quick to cut with standard hand or power tools, and the finished floor covering can follow in the same working day — a significant commercial advantage over traditional floor-prep methods.
| Heat-Pak® Technical Specifications |
| Product Code |
UNIHEAT-PAK |
| Total Thickness |
7 mm (±0.2 mm) |
| Board Composition |
3 mm MDF baseboard + 4 mm MDF topboard |
| Board Dimensions |
600 mm × 1200 mm (±1.5 mm tolerance) |
| Coverage per Pack |
2.88 m² |
| Thermal Resistance (TOG) |
0.7 |
| Adhesive System |
Factory-applied interactive contact adhesive (both boards) |
| Joint Configuration |
Staggered overlap — prevents ghosting through finish floor |
| Core Material |
High-quality MDF (Medium Density Fibreboard) |
| Compatible UFH Types |
Electric cable, mat, foil & film systems; hot-water (hydronic) UFH |
| Suitable Floor Coverings |
LVT, vinyl sheet, linoleum, rubber, cork, carpet (glue-down) |
| System Type |
Free-floating, dry installation — no setting time |
| Impact Sound Reduction |
Up to 21 dB ΔLw (with Heat-Blok® + glued linoleum, per EN-ISO 10140-3:2010)* |
| Certification |
NSG Certified; FSC Certified (FSC C154437) |
| Manufacturer |
Unifloor B.V., Deventer, Netherlands (UK) |
* Impact sound reduction measured on a standard concrete floor under laboratory conditions. Results on timber substrates will differ.
🔧 Installation Overview
Heat-Pak® is designed for rapid, tool-light installation by professional flooring contractors and competent self-installers:
- Install your underfloor heating system in the normal manner and test per manufacturer instructions.
- Lay the 3 mm MDF baseboards directly over the heating element, staggering joints from the topboard layer.
- Press the 4 mm MDF topboards onto the baseboards — the factory-applied contact adhesive bonds instantly on full-surface contact.
- Cut boards to size at room perimeters using a standard hand saw, jigsaw or circular saw.
-
Glue down your chosen resilient floor covering immediately — no waiting time required.
● For electric UFH: lay Heat-Blok® insulation beneath the element before installing Heat-Pak® above it for optimum efficiency and sound reduction.
Frequently Asked Questions
What makes Heat-Pak® different from using a single sheet of plywood or hardboard? +
Traditional single-layer ply or hardboard overlays have their joints in one plane — if the board edges are not perfectly feathered, the joint lines can reflect (ghost) through thin or high-gloss floor coverings like LVT or polished vinyl.
Heat-Pak® uses a dual-layer staggered overlap joint system that eliminates this problem by offsetting the board edges between layers. The factory pre-applied contact adhesive removes the need for a secondary bonding product between layers, and the MDF core has a far lower TOG than cement-based levelling compounds, allowing more UFH heat to reach the floor surface.
Can Heat-Pak® be used with hot-water (wet) underfloor heating, or only electric systems? +
Heat-Pak® is fully compatible with both electric and hot-water underfloor heating systems. The boards are installed directly over electric cable, mat, foil and film elements, or over hot-water pipe arrays embedded in screed or on a low-profile system. The low TOG 0.7 rating applies equally to both UFH types, ensuring minimal thermal resistance above the heat source.
Do I need to use Heat-Blok® insulation with Heat-Pak®? +
Heat-Blok® is not required for Heat-Pak® to function, but it is strongly recommended for electric UFH installations. Without insulation beneath the heating element, a significant portion of heat energy is directed downward into the subfloor rather than upward through the finished floor surface — increasing running costs and warm-up times.
Heat-Blok® (6 mm, TOG 1.9) placed beneath the electric element creates the ideal thermal sandwich: low resistance above (TOG 0.7 Heat-Pak®), high resistance below (TOG 1.9 Heat-Blok®). This combination also achieves up to 21 dB ΔLw impact sound reduction with glued linoleum.
Which floor coverings can be glued directly to Heat-Pak®? +
Heat-Pak® is suitable as a direct glue-down substrate for all major resilient and soft floor coverings, including:
- Luxury Vinyl Tile (LVT) and LVT planks
- Sheet vinyl / vinyl flooring
- Linoleum (lino)
- Rubber flooring
- Cork flooring
- Carpet (glue-down installation)
It is not designed as a substrate for click-lock floating floors (which require a separate floating underlay), nor for stone, porcelain tile or rigid natural hardwood.
How much product do I need to order and how do I calculate coverage? +
Each pack of Heat-Pak® covers 2.88 m². To calculate the number of packs required: measure your room area in square metres, add 5–10% for cutting waste (more for rooms with complex shapes or many doorways), then divide by 2.88 and round up to the nearest whole pack.
Example: A 15 m² room with 10% waste allowance = 16.5 m² ÷ 2.88 = 5.73 → order 6 packs.
Can Heat-Pak® be used over a floor cooling system? +
Yes, Heat-Pak® can be installed over floor cooling systems, but a moisture monitoring system must be installed beneath the boards. Cooling circuits can bring the subfloor surface below the dew point, causing condensation to form — which can affect both the MDF boards and the adhesive bond of the floor covering above. Always consult your UFH/cooling system supplier for appropriate moisture management before proceeding.
