Thermoblock solves cold bridging at the wall-floor junction. With increases in envelope insulation required to meet European Energy Directives, heat loss at thermal bridges will become proportionally more significant. Improved fabric insulation will therefore accentuate the loss at thermal bridges (Y-Value).



A load bearing thermal insulation block which elimates the cold bridge at the wall/floor junction.

Marmox Thermoblock is a block of load-bearing insulation material designed to be placed at the base of a masonry or timber-frame wall to address the thermal bridge. Its thermal conductivity is 0.05W/mK which will result in a significant reduction in y values when used at wall to floor junctions.

Its mean compressive strength is 9N/mm2 allowing it to be used under most load-bearing walls and its characteristic shear strength is 0.18N/mm2. Additionally, because they are impermeable to water they can be used in damp conditions without any loss of their insulating properties. So, not only do Thermoblock thermal insulation products reduce thermal bridging, but they also create a moisture barrier.


Thermoblock applications include the following:

  • Cavity wall and ground floor junction (Masonry/Timber Frame/LGS)
  • Internal wall and floor junctions
  • Under window and door Thresholds
  • Base of ICF walls
  • Base of parapet walls

Typical Timber Frame Detail – External U value of 0.11


Junctions incorporating the 100mm and 140mm wide block have been thermally modelled to provide a series of psi values and temperature factors (surface condensation factor fRSI) for two wall types:

  1. With cavity walls: a) slab on ground, b) beam and block, c) suspended timber frame.
  2. With timber frame construction: a) slab on ground, b) suspended timber frame

Thermoblock provides a layer of insulation with the compressive strength of a load bearing masonry block (9N/mm2)

Thermoblock is constructed of 60mm of fire resistant XPS insulation, which encase two rows of high strength epoxy concrete columns. These are fixed to the top and bottom of the block by two layers of 2.5mm polymer modified concrete incorporating innovative carbon- nano tube technology.

Thermoblock has a thermal conductivity (λ) of 0.047W/mk

Using 100mm Thermoblock with 100mm Aerated concrete blocks delivers Ψ value of 0.031

Using 140mm Thermoblock with 140mm Aerated concrete blocks delivers Ψ value of 0.030

A single course of Thermoblock (100mm*65mm(ht)) is designed to be the starter course of the inner leaf of the wall. It is fixed to the floor with normal mortar.

Thermoblock is not an aerated/AAC/aircrete block. It is designed specifically to eliminate the cold bridge at the base of a wall made of thermal, aerated blocks.

Fire Resistance – Euroclass E (EN 13164)

Product Features

Standard sizes as follows
65mm* 100mm (1.6 kg)
65mm* 140mm (1.9 kg)
65mm* 215mm (2.5 kg)
  • Table of charactertistics

  • Thermoblock Technical brochure.pdf

  • ThermoblockSpecifications.pdf

  • BBA Certificate.pdf

  • BCCA Certificate.pdf