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LECA速 blocks Applications Solid walls Cavity walls Basement walls Foundations

Properties Dry density: 600 kg/m続 Compressive strength 3.0 MPa Frost-resisting Non-combustible Inorganic



LECA, initial letters for Light Expanded Clay Aggregates, consists of small ceramic grains manufactured in rotary kilns. The raw material is plastic clay, which is extensively pretreated and then heated and expanded at a temperature of approximately 1100 属C. The LECA grains internal cellular structure with thousands of air-filled cavities gives heat insulation properties and high strength.

LECA building blocks are inorganic and not susceptible to attack by dry-rot, wet-rot or insects. LECA building blocks are frost-resisting. This is well documented from practical use over many years. Examples from Denmark include high exposure farm buildings, foundations and external basement walls. LECA building blocks have also shown excellent performance under arctic conditions in Greenland. LECA building blocks are non-combustible and according to decision from the European Commission to be considered as reaction to fire class A ( no contribution to fire ) without the need for testing.

LECA速 blocks LECA building blocks are solid or hollow blocks of lightweight aggregate concrete. The base product is LECA. LECA building blocks are produced by mixing LECA with cement, flyash and water. The blocks are cast in special machines that compact and vibrate the concrete in one single operation.

Dimensions The nominal face size ( length x height ) for LECA blocks is always 490 x 190 mm. The block thickness and corresponding block weight is according to the table. Block thickness mm






The accumulation of heat in inner-leaf walls and partitions made of LECA building blocks make a major contribution to the creation of a pleasant indoor climate by neutralizing temperature fluctuations by 330 350 390 sunshine or ventilation.

Block weight kg







The Block weight is the average unit weight including normal humidity content.

The absorption of moisture by LECA building blocks is minimal. The block structure with large pores between the LECA, grains forms effective protection against sorption. 23,0


Danish LECA building blocks are supplied in block class 3,0 MPa with a normal dry density of 600 kg/m続.

Outer walls Outer walls made of LECA building blocks enable fast and easy building. The blocks provide strong, robust walls and have a positive effect on the heat insulation and the indoor climate in the house.

Inner- leaf walls and partitions LECA blocks for Inner- leaf walls and partitions are normally the 100, 150 or 190 mm blocks. The blocks are lightweight and easy to handle.

Basement walls

Thermal insulation The thermal conductivity for Danish LECA blocks is according to the following table. Thermal conductivity W/m K

Block wall with joints

LECA blocks alone

Outside application



Inside application



Thermal insulation values, U-values, for LECA block walls are, according to Danish ruler for the calculation of heat loss from buildings, according to the following table. Block thickness mm






U-value W/m² K






LECA building blocks provide warm, dry basements. Basement outer walls must always be equipped with perimeter drains. Below ground level, basement walls build of LECA building blocks must be grounded, asphalted and coated with mortar.

Foundations Topping the head of outer-wall foundations with two rows of LECA building blocks provides effective floor protection at the coldcritical point adjacent to the concrete floor slab.


Surface treatment

Walls and foundations made of LECA building blocks must be build in bond. The joints must be uniform throughout the cross section, unless specified otherwise. LECA building blocks absorb almost no water but can naturally become saturated by lengthy rain. LECA building blocks and LECA block constructions should therefore always be provided with weather protection.

The low moisture absorption and large surface pores make LECA blocks suitable for rendering and plastering by both manual and mechanical means.

Shaping The best tool for dividing and shaping the LECA building blocks is a carbide-toothed saw. Minor jobs can be accomplished using an axe or masonry hammer. LECA blocks are quickly divided using a standard block cutter.

The LECA速 trademark All rights to the manufacture of LECA and to use of the LECA trademark are owned by Leca Trading & Concession A/S in Copenhagen, Denmark.

The purpose of this brochure is to provide useful information concerning the properties and applications of LECA products. The information is intended to serve as a source of inspiration to persons responsible for the planning and implementation of individual projects. LECA-Buildinginformation accepts no responsibility for the information contained in this brochure and no legal liability for dimensioning and project planning performed in accordance therewith.

Dansk Leca A/S Telephone Telefax E-mail

+ 45 87 61 02 01 + 45 87 61 02 05

LECA® Building Blocks