A medium dense, loadbearing block, suitable for general purpose walling applications. The block provides good all round technical performances with a high content of recycled material.


Available throughout the east, south east, london & BEYOND

Visit our merchant locator to the left for our current list of merchants. We have the ability to deliver nationally, please contact our sales team for further details.


AshGP – Medium density, loadbearing units, suitable for general purpose walling applications.  It combines good all round technical performance with a high content of recycled material.

General Properties – Table 1

Face Size 440mm x 215mm
Dimensional Tolerances Category: D1
Mean Unit Strength 3.6, 7.3, 10.4N/mm2
Net Dry Density 1450 kg/m3
Thermal Conductivity (W/mK) 0.47 at 3% moisture content (Internal use)
0.51 at 5% moisture content (External use)
Moisture Movement <0.5mm/m
Reaction to Fire Class A1
Configuration Solid Blocks: Group 1
Specific Heat Capacity 1000 J/kg/K
Water Vapour Diffusion Coefficient µ =  5/15  (Tabulated value from BS EN 1745)
  • Suitable for various applications above and below ground
  • Good surface key for the direct application of plasters and renders
  • Provides a strong background for all types of fixings

Ash GP  is a medium density concrete block which is robust, durable and suitable for a range of walling applications. Typical uses include the inner leaf of cavity walls when used with cavity insulation, separating or partition walls, and  infill blocks in beam and block flooring systems. Ash GP can also be used externally where rendering or cladding is to be applied to the wall. Ash GP blocks provide a strong background for holding fixings.

Ash GP is produced using recycled aggregate thereby conserving valuable sources of primary material.

Fire Resistance

The fire resistance periods of Ash GP loadbearing and non-loadbearing walls are shown in Table 5

This data is only valid for walls complying with BS EN 1996 Part 1-1, Part 2 and Part 3. For walls designed in accordance with BS 5628, fire resistance values can be confirmed with our Technical Department.

The thicknesses given in Tables 5 are for masonry alone, excluding finishes. For the fire resistance of walls with finishes, refer to the Lignacite Design Guide – Fire Resistance.

Fire resistance of Ash GP blocks – Table 5

Solid blocks (Group 1 units) –

no finish

Non-loadbearing wall

(criteria E1)

Loadbearing wall

(criteria RE1)

a 1.0 a 0.6
100mm 3 hour 2 hours 3 hours
140mm 4 hours 3 hours 4 hours


  1. These Tables are only valid for walls complying with BS EN 1996 Part 1-1, Part 2 and Part 3. For walls designed in accordance with BS 5628, fire resistance values from that Standard are available on request.
  1. Criteria E1 refers to walls with a separating function. Criteria RE1 refers to walls with a separating and loadbearing function.
  1. This Table is derived on data from the National Annex to BS EN 1996-1-2. References to a ≤ 1.0 and a ≤ 0.6 refer to the proportion of load on a wall.

If unknown, we suggest the values for a ≤ 1.0 are used as these are ‘worst case’ values.

Surface Finish Recommendations

Drylining – Application to be as manufacturer’s recommendations.

Dense Plaster – Apply either 1:1:6 cement:lime:sand or 1:4 ½ Masonry cement:sand or 1:5 ½ cement:sand and plasticiser. Alternatively: Thistle Bonding or Thistle Hardwall or Knauf Ultimate backing plaster.

Finishing Coats – Thistle plaster finish or Thistle multi-finish or Knauf Multi cover.

External Rendering – Rendering to be in accordance with BS EN 13914-1. Avoid over strong mixes. Ensure the first coat of render is applied to a greater thickness than successive coats. Ensure the first coat of render is applied to a greater thickness than successive coats. Builders considering the use of proprietary render systems must exercise caution to accurately adhere to the render manufacturers’ design and specification instructions. Detailed guidance is also published in the NHBC Standards, Chapter 6.11- Render.

Strictly adhere to the specific application instructions, paying particular attention to prevailing weather conditions and the minimum recommended thickness of single coat renders.


Responsible sourcing – Lignacite Ltd operates its manufacturing plants to a BSI certified Environmental Management System (EMS) complying with ISO14001. Lignacite Ltd. complies with the requirements of BES 6001 – Framework Standard for the Responsible Sourcing of Construction Products, Certificate No: BES 580823. This independently confirmed Responsible Sourcing Certification provides re-assurance to our customers that they are procuring products responsibly and sustainably. Credits can also be gained under environment assessment schemes such as BREEAM and the Code for Sustainable Homes.

Environmental ratings – Summary green guide ratings applicable to Ash GP blocks can be obtained from the BRE Green Guide to Specification.

Thermal Resistance

The thermal resistance values (m 2 K/W) for AshGP are shown in Table 3. The values are derived by dividing the block thickness by its thermal conductivity (W/mK).

Thermal Resistances – Table 3

Thermal Resistance (m2 K/W)


Form 3%




100 Solid 0.212 0.196
140 Solid 0.298 0.274

Note: 3% moisture content (m/c) should be used for protected locations such as the inner leaf, and 5% for exposed locations such as the outer leaf when rendered

Thermal insulation

Ash GP blocks can be used to satisfy the requirements of Part L of the Building Regulations.

Presented are the U-values for a range of wall constructions based on 100mm Ash GP blocks in conjunction with full and partial cavity insulation. The outer leaf is facing brick, but a rendered block outer leaf will usually achieve at least the same U-value

For constructions not shown please contact our Technical Department (tel 01842 810678) who will be pleased to provide confirmation of performance.

Full Cavity Fill and 100mm Ash GP blocks

U-values (W/m K)


Cavity fill type

12.5mm plasterboard    on dabs 13mm lightweight plaster
Internal finish
100mm DriTherm Cavity Slab 32 Ultimate 0.26 0.27
100mm DriTherm Cavity Slab 34 Super 0.28 0.29
100mm Isover CWS 32 0.26 0.27
100mm Isover CWS 36 0.29 0.30
100mm Xtratherm Cavity Therm 0.19 0.19
100mm Kingspan Kooltherm K106 0.17 0.18
125mm DriTherm Cavity Slab 32 Ultimate 0.22 0.22
125mm DriTherm Cavity Slab 34 Super 0.23 0.24
125mm Isover CWS 32 0.22 0.22
125mm Isover CWS 36 0.24 0.25
125mm Xtratherm Cavity Therm 0.15 0.15

Partial Cavity Fill and 100mm Ash GP blocks

U-values (W/m K)


Cavity fill type

12.5mm plasterboard    on dabs 13mm lightweight plaster
Internal finish
50mm Celotex CW4000 0.28 0.29
50mm Kingspan Kooltherm K108 0.24 0.25
60mm Celotex CW4000 0.25 0.25
60mm Kingspan Kooltherm K108 0.21 0.22
75mm Celotex CW4000 0.21 0.22
75mm Kingspan Kooltherm K108 0.18 0.19

Notes to tables:

  1. The U-values shown are based on the use of various proprietary insulation products. Alternative products can be used, provided they can achieve an equivalent thermal resistance (m2K/W).
  2. Wall ties are assumed to be stainless steel with a cross-sectional area of no more than 12.5mm2 for structural cavities up to 125mm wide.
  3. The suitability of full fill cavity insulation materials will depend on exposure conditions and should be confirmed by the designer. For partial cavity fill, a 50mm residual should be maintained. In some cases it may be possible to reduce the cavity width to a minimum of 25mm. The insulation manufacturer should be consulted for guidance.


Ash GP blocks are BSI Kitemarked approved to BS EN 771-3. They are Category 1 masonry units manufactured under a BSI certified Quality System complying with BS EN 9001.


Ash GP blocks are manufactured with a scratched surface to aid the key of plaster and render finishes. They have a face size of 440m x 215mm and are available in 100mm and 140mm widths in solid form only.


Ash GP blocks can be considered for use in the following locations:

  • Inner and outer leaves of external cavity walls
  • Internal walls, including fire break walls
  • Separating walls including those conforming to Robust Detail specifications
  • External and internal walls below ground (7.3N/mm 2 strength blocks should be used to walls exposed to the external ground)
  • Infill units to beam and block flooring

Unit and laid weight

Typical units and laid weight for AshGP are shown in Table 2.

Block Weights – Table 2



Form Unit Weight (kg) Laid Weight


100 Solid 14.0 150

Note: Weights are based on 3% moisture content by weight.

Sound Insulation

Ash GP blockwork provides excellent levels of sound insulation between buildings and adjoining rooms. It can be used in party wall constructions, based on lightweight blockwork specifications, detailed in Approved Document E to the Building Regulations. It can also be used to construct party walls meeting Robust Detail specifications eg. Robust Details E-WM-2, 4, 8, 11, 14, 17, 20, 21, 22, 27 and 28.

Sound Reduction – Table 4

Sound Reduction Index Rw (dB)


Form L/tweight Plaster 12.5mm


100 Solid 45 44

Notes: The above values are based on technical assessments and tests to BS EN ISO 140-3 Surface finishes are assumed to be applied to both wall faces.

Thermal Bridging

A significant factor in thermal assessments is the heat loss through thermal bridges (known as non–repeating or linear thermal bridges).

These occur at junctions between elements or where the continuity of the external fabric insulation is interrupted (e.g. at junctions with external walls, floors and roof). Assessors will need to apply a PSI (y) value to the particular junction being measured.

The Concrete Block Association (CBA) have developed a comprehensive set of junctions that have been independently assessed. The results clearly demonstrate that constructions using Ash GP aggregate blocks can be assigned improved performance when compared to the Government’s Accredited Construction Details and Default values shown in Appendix K of SAP 2012.

As a member of the CBA, Lignacite Ltd is able to advocate the use of these enhanced bridging details. This information will be of interest to designers and SAP assessors as well as builders who will have the responsibility for correctly constructing the various junctions.

Junction details and PSI (y) values can be accessed at www.


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

Movement Control

Movement joints should be considered in accordance with PD 6697 at approximately 6.0 metre 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 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.