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New Solution for Masonry Cavity Walls


Thermal Economics, a leading manufacturer of thermal and acoustic insulation technology, have introduced a new product Alreflex Full Fill for use in masonry cavity walls.  Alreflex Full Fill was introduced to the market on 22nd August 2017; which is when the BBA approved Alreflex Full Fill with Agrément Certificate 93 / 2861 (Product Sheet 8).


Alreflex Full Fill was designed so that it can be installed by a general builder or any other contractor experienced with installing rigid, full-fill insulation boards in masonry cavity walls.  The wall should be constructed so that the Alreflex Full Fill is fastened to the cavity face of the inner-leaf.  The spacing of the wall-ties should be such that the long edge of the board is secured at two points (minimum); and all joints are taped over with our Alreflex breathable tape.  Corners are taped with our Alreflex aluminium tape to preserve the low-emissive face and prevent thermal bridging.

The outer-leaf is constructed to allow a 10 mm cavity between the outer-leaf and the foil face of the Alreflex Full Fill board.  Excess mortar squeeze should be removed and all mortar droppings cleaned from the foil face so that the residual cavity creates an additional, insulating layer against radiated heat flow.

The challenge

Supply shortages of AAC blocks has resulted in housebuilders using dense aggregate blockwork with poorer thermal performance to construct masonry cavity walls.  However, the Building Regulations allow for no reduction in fabric energy efficiency, as the UK is still committed to driving towards nearly-zero energy buildings as part of complying with the EU Energy Performance of Buildings Directive, and shortages of PUR / PIR insulation has led to further cost increases and delays in build programmes.

Although the dense blocks are cheaper than AAC blocks, more insulation has to be used; widening the cavities which also means that bigger wall-ties and lintels have to be used; which leads to greater heat loss by thermal bridging and results in greater costs.

The solution

Alreflex Full Fill is manufactured from graphite-enhanced expanded polystyrene (which is more cost-effective than PUR / PIR & phenolic foam alternatives) and allows for a thicker insulation board to be installed without widening the cavity; eliminating the consequential costs of bigger wall-ties and lintels and demonstrates a reduction in thermal bridging!

The foil-and-bubble laminate provides an effective cavity rain barrier to prevent rainwater ingress from driving rain, which also means that Alreflex Full Fill is suitable for use in severe exposure zones; and the low-emissive surface limits radiated heat loss across the 10 mm cavity, ensuring the full depth of the cavity is insulated.

If carefully removed, Alreflex Full Fill boards can be reused on other construction sites; or recycled to make more expanded polystyrene products (A+ BRE Green Guide rating). Any residual gases released from Alreflex Full Fill have a Global Warming Potential less than five times that of carbon dioxide and no O-zone depletion potential.

Alreflex Full Fill can be ordered from most builder’s merchants and distributors and is available throughout the United Kingdom.  For more information please visit the Alreflex Full Fill page on our website to download BBA certificates and technical data.  Thermal Economics can also provide U‑value and condensation risk assessments on request by contacting our technical department on 01582 544255 or email technical@thermal-economics.co.uk.

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