Wet Underfloor Heating

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Wet Underfloor Heating

For more than 20 years, Gondwana Green Heat has been supplying, designing, installing, repairing and commissioning wet underfloor heating systems across the UK. Today, most of the new‑build and major refurbishment projects we work on include wet underfloor heating — and with good reason. It delivers exceptional comfort, outstanding efficiency and seamless integration with modern low‑temperature heating technologies.

Wet underfloor heating uses a network of high‑efficiency pipes installed beneath the finished floor surface. Warm water from the central heating system circulates through these pipes, gently heating the floor and creating a stable, even temperature throughout the room.

What Is Wet Underfloor Heating?

Wet underfloor heating is a hydronic heating system built directly into the floor structure. Durable, oxygen‑barrier pipes are laid in carefully designed circuits — either embedded within screed or installed in low‑profile retrofit panels. Warm water flows through these pipes, turning the entire floor into a large, low‑temperature heat emitter.

Because the system operates at significantly lower flow temperatures than traditional radiators, it delivers improved comfort, reduced running costs and a consistent heat profile. It’s ideal for well‑insulated homes, Passive House projects and renewable heating systems such as heat pumps, biomass and solar‑thermal.

How It Works

Heat distribution — The floor warms evenly, eliminating cold spots and draughts.
Low‑temperature operation — Perfect for heat pumps and biomass systems, reducing running costs.
System integration — Works seamlessly with modern controls, zoning and renewable technologies.
Design flexibility — Suitable for screed floors, timber floors and ultra‑low‑profile retrofit systems.

Benefits of Wet Underfloor Heating

Improved comfort — Warm, even heat across the entire floor surface delivers exceptional comfort, from toasty toes to contented dogs.
Lower running costs — Underfloor heating operates at reduced flow temperatures, using less energy than conventional radiators.
Even heat distribution — Heat rises uniformly from the floor, removing cold spots and creating a stable, consistent room temperature.
More usable space — No radiators means clean walls, flexible room layouts and more freedom for furniture and interior design.
Quiet, low‑maintenance operation — With no moving parts in the floor, the system runs silently and requires minimal upkeep.
Ideal for commercial spaces — Perfect for large open‑plan areas where consistent, evenly distributed heat is essential.
Compatible with all heating technologies — Works seamlessly with heat pumps, biomass, solar‑thermal and traditional gas or oil boilers.
Adds a sense of luxury — A premium heating solution that enhances comfort, improves efficiency and can increase property value.

Types of Floor Construction and Build‑Up Options

One of the most common questions we’re asked is: what’s the best floor construction for wet underfloor heating? Should the pipework be embedded in concrete, or fitted between timber joists?

The answer is consistent: pipework embedded in a solid mass — typically concrete or screed — will always deliver the best thermal performance. A solid floor provides excellent heat transfer, stable output and high efficiency.

That said, most UK homes (new‑build and retrofit) use suspended timber floors. Installing wet underfloor heating in timber structures is not new to us — we’ve been doing it successfully for over 20 years. There are three main suspended‑timber systems, each suited to different build‑ups and project requirements. The final option is the one we recommend most often.

Suspended Timber Floor Options

Overlay insulated panels Typically used in retrofit projects. A PIR‑based insulated panel with foil facing is laid over the existing floor, pre‑routed to accept the pipework. A new timber or gypsum deck is installed on top. Quick, clean and ideal where floor height increases are acceptable.
Aluminium heat‑spread plates Insulation is fitted between the joists. Aluminium plates with pre‑formed pipe channels are fixed to the joists, with pipework clipped into the grooves. A timber or gypsum deck is laid over the top. A reliable, lightweight solution with good heat distribution.
Pipes clipped over insulation with thin screed (our preferred option) Insulation is installed between the joists. Pipework is clipped directly onto the insulation, then covered with a thin sand‑cement screed to create a continuous thermal mass. A timber or gypsum deck is installed above. This method offers the best heat spread, stability and efficiency in timber floors.

Solid Floor Options

Solid floors offer the highest performance because the pipework is fully encased in a continuous thermal mass.

Insulation over structural concrete Insulation is laid over the structural slab. Pipework is clipped either to the insulation or to a light welded mesh (our preferred fixing method for accuracy and stability). The floor is then poured in the chosen material.
Integrated structural slab systems In some projects, the pipework is incorporated directly into the structural concrete pour. This reduces build‑up height and can save material. Careful design is essential to ensure correct flow temperatures and structural performance.

Screed and concrete options include:

Standard hand‑mixed concrete
Batching‑plant concrete
Decorative concrete finishes
Calcium sulphate (anhydrite) screeds — fast‑drying, smooth and naturally anti‑bacterial
Limecrete breathable screeds — a vapour‑open, flexible, low‑cement alternative ideal for heritage buildings, moisture‑sensitive floors and projects requiring breathable construction. Limecrete works exceptionally well with underfloor heating due to its thermal mass and ability to regulate moisture naturally.
Other cement‑based liquid pumped screeds

Each offers different drying times, thermal characteristics and installation advantages.