Home > Companies > Thomas Armstrong (Concrete Blocks) Ltd > AIRTEC Large Format Block

Autoclaved Aerated Concrete (AAC) large format blocks available as flooring and wall blocks.

Flooring block:

  • For use in block and beam floors to provide significantly improved thermal insulation of ground floors and quick, easy installation.
  • Can be laid in either the 620 or 430 mm width, offering a choice of reinforced inverted T-beam centre spacing of 705 and 515 mm respectively.
  • Provides an excellent substrate for application of screed and floating floor finishes. Can be easily cut, bored and shaped where required for simple installation around services and are suitable for use with under-floor heating systems.

- Applications:

  • Infill for block and beam flooring.
  • Fire resistant applications.

Wall block:

Designed to provide significantly improved thermal insulation and air-tightness of internal and external walls by reducing the proportion of mortar joints in a wall. If using a thin joint construction this is further reduced by around 87% when compared to conventional walls using 10 mm mortar joints.

- Applications:

  • External or internal leaf of cavity walls.
  • Loadbearing and non-loadbearing walls.
  • Party/ separating walls to Building Regulations (E&W) Approved Document E.
  • Robust detail party walls, flanking, partition and fire resistant walls.

Freeze/ thaw resistant.

Related literature

The following content references this product:

Standard product features

Face size:

620 x 430 mm.


10 mm.

Compressive strength (minimum):

> 3.6 N/mm².

Transverse strength (minimum):

> 3.5 N/mm².

Thermal conductivity:

0.13 W/mK.

Fire resistance category:

Class A1.

Tolerance category (dimensional classification):


NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
45-80-50/362 Autoclaved aerated concrete (AAC) infill blocks

NBS Specification

NBS Buliding logo
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

AIRTEC Large Format

Manufacturer details

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