Lignacrete: High Strength Block Datasheet
Side view of a Lignacrete High Strength Concrete Block

Lignacrete High Strength Block

Lignacrete 17.5, 22.5 and 30N/mm² are high strength dense concrete blocks that are ideal for walls needing exceptional loadbearing capacity. Manufactured to BS EN 771-3, these blocks are also extremely robust and durable with a technical performance that will meet most applications.

Generally, 100mm and 140mm blocks have a face size of 440mm x 215mm. Lignacrete 140mm Midi blocks have a face size of 290mm x 215mm and have been developed for easier handling while maintaining all of the performance of conventional size solid units.


Specification & Application

Weights & Pack Sizes

All weights are approximate and subject to normal variations in raw materials.

Table 1 – Block Weights and Pack Sizes

Thermal Properties

Cavity fill typeInternal finish -
12.5mm plasterboard on dabs
U-values (W/m² K)
Internal finish -
13mm lightweight plaster
U-values (W/m² K)
60mm Celotex CW40000.250.26
75mm Celotex CW40000.220.22
100mm Celotex CW40000.170.18
60mm Kingspan Kooltherm K1080.240.23
75mm Kingspan Kooltherm K1080.200.20
100mm Kingspan Kooltherm K1080.160.16
60mm Eurowall Cavity0.250.26
75mm Eurowall Cavity0.240.22
100mm Eurowall Cavity0.170.18
100mm Rockwool Partial Fill0.270.28
150mm Rockwool Partial Fill0.190.20
170mm Rockwool Partial Fill0.170.18
100mm Isover CWS 320.260.27
125mm Isover CWS 320.220.22
150mm Isover CWS 320.180.29
Cavity Fill Table's Notes:
(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 (m² K/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 (always check the manufacturer’s guidance).



Block Wall Ties

Under normal conditions, wall ties should be embedded 50mm into the mortar on each leaf, staggered in alternate courses and spaced in accordance with the following.

Table 5 – Wall Tie Spacings

Leaf Thickness
Cavity Width
Horizontal Spacing
Vertical Spacing
Ties per m²
Less than 90mm50 - 754504504.9
Over 90mm50 - 1509004502.5

Design continued...

Block Mortar

Generally, the mortar type for work above ground level should be designation (iii) / Compressive Class M4. However, where it is needed to maximise the loadbearing capacity of the wall, designation (ii) / Compressive Class M6 mixes should be specified. Stronger mixes may also be required for work below ground.

Table 6 – Mortar Mixes

Site Practice

Lignacrete block:

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Product data updated: 15th Jul 2024

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