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Marmox ThermoblockA load bearing thermal insulation block which eliminates 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.

Call us today on 01634 835290 or leave us a message on our contact page to learn more about our Thermoblock thermal insulation products, as well as our range of sound absorptions products and waterproofing products.

Marmox Thermoblock can be associated with the NBS clause: “F30-185 - accessories/ sundry items for brick/ block/ stone walling”

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Guaranteed Compliance to Building Regulations

Thermal Insulation BlockAll building regulations in the UK and Ireland now say: “The building fabric should be continuous over the whole building envelope and constructed so that there are no reasonably avoidable thermal bridges in the insulation layers caused by gaps in the various elements.”

Marmox Thermoblock satisfies this requirement perfectly by connecting the wall insulation with the floor insulation.

The BBA certified Thermoblock thermal insulation was created to provide an easy, affordable and effective solution for the problem of thermal bridging. One junction of major concern has been where the wall (masonry OR timber frame) meets the floor but using Marmox Thermoblock will guarantee compliance with current regulations and also with proposed zero carbon regulations.

How to Design a Thermally Efficient Wall-Floor Junction

Thermal Insulation ProductsMarmox Thermoblock thermal insulation is NOT an aircrete thermal block. Typically it replaces the bottom row of aircrete blocks to stop the cold bridge at the critical wall/floor junction.It can also be used at the base of a timber frame or steel frame wall.  Standard specifications for several applications are detailed in the instructions section at the bottom of this page.

The standard Thermoblock thickness in the UK is 65mm, which is the same height as a brick. We also manufacture Thermoblocks 100mm thick which offers even greater insulation.

To create a continuous uniform barrier, the block ends should be sealed together using our sealant, Marmox MSP360. for usage refer to specification sheets below.

BRE Third Party Accredited Junction Details - Thermal Models

Thermal Insulation under brickworkThe performance of Marmox Thermoblock thermal insulation in several common wall/floor junction details has been independently assessed and certified by the BRE. The BRE scheme offers an on-line database of independently assessed and certified thermal junction details which can be used in the SAP/SBEM energy assessment of the building to ensure it meets the appropriate UK and Irish building standard requirements. Using these results will save architects and designers both time and money because they will not need to have their designed modelled themselves.

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:

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

With timber frame construction: a) slab on ground, b) suspended timber frame.

Architects and Energy Assessors simply log onto BRE’s site and click the junction type required. BRE-Global is a UKAS accredited laboratory which gives confidence and assurance to designers that using Thermoblock thermal insulation in the common positions that have been modelled can guarantee compliance to the appropriate building standards. The full report with the results and thermal model drawings is given below in the "Datasheets" section.

Marmox Thermoblock-PIR

To insulate beneath parapets or if bituminous membranes are being applied using a flame gun, Marmox Thermoblock-PIR, the flame resistant version must be used. These blocks are 53mm thick and available in 100mm and 140mm wide versions and are designed to be resistant to distortion that a flame gun might cause on the standard XPS version.

PLEASE NOTE: 'Thermoblock-PIR' is not stocked in the UK. It is made to order and therefore there is a 6 - 8 week lead time. Standard versions are always kept in stock but if you require this version you should order a couple of months in advance.

Marmox - the thermal insulation experts

One of the easiest and most affordable ways to significantly cut the amount of energy used by a home, office building or public premises is by making use of effective insulation products - and the Thermoblock from Marmox is one solution that can certainly make a difference. Whether you're interested in making a building more environmentally friendly, meeting regulations or simply cheaper to keep warm in the winter, Thermoblock could be the perfect solution to thermal bridging problems. In addition to the BRE accredited designs, we can offer a limited and basic thermal modelling analysis of your specific junction type.

Here at Marmox, we are experts in providing sustainable and cost-effective building products to construction and refurbishment professionals around Ashford, Chatham, MaidstoneKent, London, Bromley, Gillingham, Sittingbourne, Canterbury, Tonbridge and the UK and Ireland. We supply the product both through the major nationals and through our independent stockists across London and Kent.


Marmox UK partners with NBS to provide complete NBS Plus product listings to help specify our products into your next project. Click here to go to the RIBA website where you can copy the relevant NBS Clauses into your document.

NBS Specification (including BIM)