ThermoSphere Self-Adhesive Underfloor Heating Decoupling Membrane | 1m² & 15m² | IP68 Wet Room Rated

Substrate restriction — read before ordering

The self-adhesive backing is only suitable for plywood or chipboard sub-floors. It is not designed to bond directly to concrete, screed, or anhydrite substrates — use the standard fleece-backed ThermoSphere Membrane (HDM-001/005/015) with a flexible tile adhesive for those substrates instead.

IP68 requires the full system

The IP68 waterproof rating only applies when this membrane is installed together with ThermoSphere Ultimate heating cable and the ThermoSphere tanking kit. The membrane alone, without the tanking accessories, does not constitute a certified wet-room waterproofing system.

Heating cable sold separately

This listing covers the membrane only. ThermoSphere Ultimate heating cable, sold separately by output and area coverage, is required to activate the underfloor heating function — the membrane can be installed on its own purely as a decoupling/waterproofing layer if heating is not required.

Dimple spacing sets your output

Pressing the heating cable into every 2nd dimple channel delivers the higher of the two available outputs, while every 3rd dimple channel delivers the lower output — the same membrane supports both settings across either cable range.

Two output ranges available

This membrane accepts two distinct ThermoSphere Ultimate cable ranges: the standard range (130W/m² or 195W/m²) for typical heat-loss rooms, and the Low Output range (57W/m² or 85W/m²) purpose-built for homes with a restricted electrical load supply or systems drawing primarily from solar generation and battery storage. Always confirm the room's heat-loss calculation supports the Low Output range before specifying it as a primary heat source.

Self-adhesive fixing

The membrane's own adhesive layer replaces the flexible tile adhesive normally needed to bond a decoupling membrane to the sub-floor, cutting a full trade step and its drying time out of the installation sequence.

Polyethylene dimple structure

A grid of rounded, square-shaped studs forms channels that key the heating cable into place at a fixed pitch, keeping cable runs even so the finished floor heats consistently without hot or cold spots.

Decoupling for crack protection

The membrane physically separates the tile bed from the sub-floor, so shrinkage, thermal movement, or minor deflection in timber substrates is absorbed by the membrane rather than transmitted up into the tile or grout joints.

Vapour-permeable waterproofing

The polyethylene sheet forms a waterproof barrier while still permitting vapour to pass through the structure, reducing the risk of moisture becoming trapped beneath the tiled surface.

Extra-heavy Robinson test rating

Independent Robinson-type testing rates the membrane for extra-heavy foot traffic, meaning the same product used in a domestic bathroom is also specified for higher-traffic commercial floor areas.

Slim 5.5mm build-up

At only 5.5mm total thickness, the membrane adds minimal height to a floor build-up compared with a traditional screed-based heating system, which matters where door clearances or step-free thresholds are tight.