Earthwool DriTherm Cavity Slabs

For masonry cavity walls

DriTherm Cavity Slab



Earthwool DriTherm Cavity Slabs have thermal conductivities ranging from 0.032 to 0.037 W/mK.


Earthwool DriTherm Cavity Slabs are classified as Euroclass A1 to BS EN 13501-1.


Earthwool DriTherm Cavity Slabs are semi-rigid or rigid slabs of non-combustible, water repellent, glass mineral wool. They are 455mm wide to suit standard vertical wall tie spacings, ensuring a closed joint with adjacent slabs.


  • British Board of Agrément approved for use in all exposure zones
  • Excellent thermal and fire performance
  • Water repellent
  • Slabs ‘knit’ together, thus eliminating air gaps between adjacent slabs


Earthwool DriTherm Cavity Slabs are for the thermal insulation of masonry cavity external walls and are installed to fully fill the cavity. They are approved for use in buildings up to 12m high in any exposure zone and for use in multi-storey applications up to 25m in height.


Earthwool DriTherm Cavity Slabs represent no known threat to the environment and have zero Ozone Depletion Potential and zero Global Warming Potential.

ECOSE® Technology

Knauf Insulation mineral wool products with ECOSE Technology benefit from a revolutionary, bio-based, formaldehyde-free binder technology, based on rapidly renewable materials, instead of petro-based chemicals. It reduces embodied energy and delivers superior environmental sustainability.

The technology has been developed for Knauf Insulation’s glass and rock mineral wool products, enhancing their environmental credentials without affecting the thermal, acoustic or fire performance. Insulation products made with ECOSE Technology contain no dye or artificial colours – the colour is completely natural.



Earthwool DriTherm Cavity Slabs are manufactured in accordance with BS EN 13162, EN 16001 Energy Management Systems, OHSAS 18001 Occupational Health and Safety Management Systems, ISO 14001 Environmental Management Systems, and ISO 9001 Quality Management Systems, as certified by Bureau Veritas.


Earthwool DriTherm Cavity Slabs are odourless, rot proof, non-hygroscopic, do not sustain vermin and will not encourage the growth of fungi, mould or bacteria.

Moisture resistance

Tests by the British Board of Agrément confirm that Earthwool DriTherm Cavity Slabs will not transmit water to the inner leaf. Nor will they transmit moisture by capillary action across the cavity or from below damp proof course level.

Vapour resistivity

Earthwool DriTherm Cavity Slabs offer negligible resistance to the passage of water vapour and have a water vapour resistivity of 5.00MNs/g.m.


Earthwool DriTherm Cavity Slabs are guaranteed* for 50 years to resist the transmission of liquid water from the outer masonry leaf to the inner masonry leaf in new cavity walls and to have a thermal conductivity of 0.032 to 0.037 W/mK at normal building temperatures

*Available by application to Knauf Insulation Ltd


Earthwool DriTherm Cavity Slabs are certified by British Board of Agrément Certificate 95/3212. Approval can be sought from Knauf Insulation Ltd and the British Board of Agrément for Earthwool DriTherm Cavity Slab’s use in buildings over 25m high.

Handling and storage

Earthwool DriTherm Cavity Slabs are easy to handle and install, being lightweight and easily cut to size, where necessary. They are supplied in polythene packs which are designed for short term protection only. For longer term protection on site, the product should either be stored indoors, or under cover and off the ground. Earthwool DriTherm Cavity Slabs should not be left permanently exposed to the elements.

Product Data

DriTherm Cavity Slab 37 Standard

Thickness (mm)Thermal conductivity (W/mK)Thermal resistance (m2K/W)Length (mm)Width(mm)Slabs per PackArea per Pack (m2)
150 0.037 4.05 1200 455 8 4.37
125 0.037 3.35 1200 455 6 3.28
100 0.037 2.70 1200 455 12 6.55
85 0.037 2.25 1200 455 8 4.37
75 0.037 2.00 1200 455 8 4.37
65* 0.036* 1.75 1200 455 10 5.46
50* 0.035* 1.40 1200 455 12 6.55
* 50mm and 65mm DriTherm “37” products are manufactured to 0.035W/m2K and 0.036W/m2K lambda respectively.
This higher specification allows the thinner 50mm and 65mm materials to achieve a robustness normally associated with thicker materials and so allows for easier installation.

DriTherm Cavity Slab 34 Super

Thickness (mm)Thermal conductivity (W/mK)Thermal resistance (m2K/W)Length (mm)Width(mm)Slabs per PackArea per Pack (m2)
150 0.034 4.40 1200 455 5 2.73
125 0.034 3.65 1200 455 6 3.28
100 0.034 2.90 1200 455 8 4.37
75 0.034 2.20 1200 455 10 5.46

 DriTherm Cavity Slab 32 Ultimate

Thickness (mm)Thermal conductivity (W/mK)Thermal resistance (m2K/W)Length (mm)Width(mm)Slabs per PackArea per Pack (m2)
125 0.032 3.90 1200 455 4 2.18
100 0.032 3.10 1200 455 6 3.28
85 0.032 2.65 1200 455 5 2.73
75 0.032 2.30 1200 455 6 3.28

All dimensions are nominal

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