Home > Companies > Thomas Armstrong (Concrete Blocks) Ltd > Ultralite Concrete Block

Designed to offer a low weight, loadbearing block with enhanced thermal properties suitable for a wide range of applications.

Manufactured from expanded clay aggregates. All sizes weight less than 20 kg.


  • Inner and outer leaf of external cavity walls over three storeys.
  • Internal partition walls.
  • Acoustic separating party walls to Building Regulations (E&W) Approved Document E.
  • BRE green guide A+ rated walls.

Manufactured to BS EN 771-3.

Related literature

The following content references this product:

Standard product features


440 x 215 mm.


Standard texture finish provides an excellent surface for mortars, renders and plasters.

Dimensional tolerance:

Category D1.

Dry density:

950–1050 kg/m³.

Thermal conductivity:

0.32 W/mK (protected inner leaf), 0.34 W/mK (exposed outer leaf).

Fire resistance to BS EN 13501-1:

Class A1.

Configuration to BS EN 1996-1-1:

Solid, group 1.

NBS Specification

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This product is associated with the following NBS Create clause:
45-80-50/300 Aggregate concrete blocks

NBS Specification

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This product is associated with the following NBS clauses:

Product specification

An important note about specifying



Thomas Armstrong (Concrete Blocks) Ltd


+44 (0)1748 810204

Product reference

Ultralite Concrete Block

Compressive strength

[3.6 N/mm²]
[7.3 N/mm²]


[90 mm]
[100 mm]
[140 mm]

Manufacturer details

Bridge Road,
North Yorkshire, DL10 7HW
Tel +44 (0)1748 810204
Fax +44 (0)1748 813950
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NBS National BIM Library