Marmox Thermoblock 150mm x 100mm x 600mm (Box of 8) Thermal Insulation Block

Marmox Thermoblock 150mm x 100mm x 600mm Thermal Insulation Block

Marmox Thermoblocks are high-performance, load-bearing thermal-break blocks designed to eliminate thermal bridging (cold bridging) at the base of walls and other critical structural junctions. They combine genuine structural load-bearing capacity with thermal insulation, allowing insulation to be placed directly beneath a supporting wall — something conventional insulation cannot do without being crushed.

Thermal bridging occurs where heat bypasses insulation — commonly at foundations, slab edges, wall bottoms and openings. The wall-to-floor junction alone can account for up to 30% of a building's total heat loss. By interrupting these highly conductive paths, Marmox Thermoblocks help meet energy efficiency targets, reduce heat loss, raise internal surface temperatures (reducing condensation and mould risk), and improve occupant comfort.

Construction

The standard Marmox Thermoblock comprises a 60mm thick core of fire-resistant XPS (extruded polystyrene) insulation encasing two rows of high-strength, low-conductivity epoxy-concrete columns. These columns are fixed to the top and bottom surfaces of the block — 2.5mm thick layers of fibre-reinforced polymer concrete incorporating Carbon Nano Tube technology — which distribute the structural load across both sides of the block.

Thermal Performance

• Thermal conductivity (lambda): 0.047 W/mK
• Compressive strength: 9 N/mm² (strong enough for a single load-bearing block course)
• Water resilience: Impermeable to water — can be used in damp conditions and in contact with soil without loss of insulation performance (vertical surfaces should be protected, e.g. with render, to discourage rodent damage)
• Typical applications can reduce the junction Ψ (psi) value substantially; in Passivhaus designs Thermoblocks help achieve thermal-bridge-free junctions (Ψ ≤ 0.01 W/mK).

Key Features

• Thermal break at structural junctions to reduce heat loss and eliminate cold bridging
• Load-bearing — designed to support structural elements without specialist fixings
• Suitable for use beneath masonry, timber-frame, steel-frame and in-situ concrete walls
• Provides compressive strength suitable for a standard block course installation
• Lightweight and easy to install — laid like conventional masonry with ordinary bricklayers' mortar; can be cut on site with a brick saw (or hand-saw through the polystyrene-only sections)
• Helps reduce condensation and mould risk by raising internal surface temperatures (achieving fRsi values typically above 0.75)
• Compatible with conventional building methods and materials
• Supports compliance with energy efficiency standards when specified

Technical Notes

• Thermoblock is a thermal bridging block — it is NOT an aerated / AAC / aircrete thermal block, and is used with (not instead of) lightweight thermal blocks.
• It is not a substitute for a Damp Proof Membrane (DPM) — a DPM must still be applied to the detail.
• Only a single course should be installed — independent testing was carried out on one course only; characteristic compressive strength cannot be guaranteed when stacked.
• What sits above and below the Thermoblock must not be narrower than the block, so load is distributed evenly across both column rows.
• Block ends should be sealed together with Marmox sealant for moisture resistance and air-tightness.