NBS Source
Fibo 850 Concrete Blocks

Fibo 850 Concrete Blocks

Lignacite Ltd Third party certifications:
  • BSI Kitemark

    BSI Kitemark

    Certificate type

Ultra lightweight, loadbearing units, suitable for general purpose walling applications.

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For use in housing or extension projects.

The product can also be used to construct walls in other buildings where there is a requirement to specify blockwork with a low weight, e.g. partition walls on floor slabs.

Can be considered for use in the following locations:

  • Inner and outer leaves of external cavity walls;
  • External and internal walls below ground (3.6 N/mm² blocks can be used in both inner leaf and internal walls; 7.3 N/mm² blocks to other locations);
  • Internal walls below ground, such as the inner leaf of external cavity walls and interior walls.

The blocks can accommodate drylining, dense plaster, finishing coats and external rendering. Consult manufacturer for further finish recommendations.


General purpose, lightweight concrete blocks for walling applications. The blocks are dark grey in colour with an opened textured surface. Available in 100 and 140 mm widths, solid form only.

Features and benefits:

  • Provides a high level of thermal insulation, reducing the amount of additional insulation required after installation.
  • Lightweight, easy to handle, and quick to lay.
  • Loadbearing.
  • Provides a high level of fire protection (Class A1).
  • For use internally and externally, above and below ground.
  • Provides a strong background for direct application of plasters and renders (no bonding agents required).
  • The clay aggregate is bloated through heat expansion to create a low density, porous surface with numerous cavities.
  • Fixings will be held securely by the block (and can be nailed in directly).
  • Credits available under BREEAM and Code for Sustainable Homes.
  • CE marked to BS EN 771-3.
  • Can be used to satisfy the requirements of Part L of the Building Regulations.

The mortar type for work above ground level should be designation (iii) / Compressive Class M4. Stronger mixes may be used only with the permission of the designer. Stronger mixes may also be required for work below ground in accordance with PD 6697. Consult manufacturer for details.

Movement joints should be considered in accordance with PD 6697 at approximately 6 m spacings. In areas of concentrated stress, such as those above and below openings, consideration should be given to the use of bed joint masonry reinforcement.

The design of walls should be in accordance with relevant design standards including BS 8103-2, BS EN 1996-1-1 and the requirements of the Building Regulations.

General information









(expanded clay aggregates and other naturally occurring raw materials and cement).


440 x 215 x 100 mm

440 x 215 x 140 mm


Pr_20_93_52_01 Aggregate concrete blocksPrimary


E60/297 Proprietary infill blocks

F10/18 Concrete facing blockwork

F10/355 Concrete common blockwork

Specification data - Aggregate concrete blocks Enhanced data


To BS EN 771-3.

Block description

Fine textured, loadbearing units for facing and general purpose applications.


Medium grey in colour with a fine textured surface.


Group 1.

Compressive strength


Mean value

3.6 N/mm².



Thermal conductivity

0.25 W/m·K at 3% moisture content (internal use), 0.28 W/m·K at 5% moisture content (external use).

Thermal resistance

0.40 m²K/W and 0.35 m²K/W.

100 mm width at 3% and 5% moisture content.

0.56 m²K/W and 0.50 m²K/W.

140 mm width at 3% and 5% moisture content.

Recycled content


Work sizes (length x width x height)

440 x 100 x 215 mm.

Unit weight: 8.7 kg.

440 x 140 x 215 mm.

Unit weight: 12.2 kg.

Tolerance category




Net dry density

850 kg/m³.

Reaction to fire

Class A1.

Water vapour permeability

5/15 µ.

Product Reference

Fibo 850 Concrete Blocks

Moisture movement

<0.5 mm/m.


1000 J/kg/K.

Sound reduction index

Rw 42–44 dB (dependent on application).

140 mm width.

Rw 40–42 dB (dependent on application).

100 mm width.

Fire resistance

2–3 hours.

100 mm width.

3–4 hours.

140 mm width only.

Third-party certification

BSI Kitemark approved.

Environmental information



Recycled content

22 %

Digital objects

Platform Compatible Version Certified to

Revit 2016





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Fibo850/950 Concrete Block

Fibo850/950 Concrete Block

Third party certifications

BSI Kitemark

BSI Kitemark

British Standards Institution (BSI) - certficate

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