Solutions to Regulations
January 2002

New Thermal Regulations
January 2002

Press Releases

Solutions to Regulations weigh in favour of Aggregate Concrete Blocks

Aggregate concrete block producers have responded to the CDM (Construction Design and Management) regulations with a range of solutions designed to reduce the need for repetitive handling of units heavier than 20kg.

The Concrete Block Association, which represents over 30 manufacturers of aggregate blocks, confirms there are a number of options available to the specifier when designing wall constructions with dense or lightweight aggregate blocks, which meet the requirement of the CDM regulations. These include:

• The use of cellular or hollow blocks in place of solid blocks for some wall constructions.For example, depending on block size used, a typical standard dense cellular 140mm block can weigh up to 7kg less than its solid counterpart. Guidance on specific solutions to ensure correct specification should be sought from manufacturers.

• The specification of a solid "midi"-sized block, available from some manufacturers. Produced in a 140mm thickness, the block has a face size of 290 x 215mm compared to the conventional 440 x 215mm. Standard blocks weigh around 17kg per unit and are usually laid in normal aspect to construct a 140mm thickness wall but in certain situations can be used flat to construct a 215mm wall.

• The construction of a double-leaf collar jointed wall. This technique uses two leaves of solid 90mm or 100mm blocks laid back to back and tied, using either bed-joint reinforcement or double triangle ties. This will create a wall thickness of either 190 or 215mm depending on block size used. Although BS5628 calls for the collar joints of such constructions to be solidly filled with mortar, practical difficulties mean this is not done and an extensive research programme carried out by CBA has shown that filling the collar with mortar has only a marginal effect on wall strength and therefore to be unnecessary. Consequently the recommendation is that no attempt be made to fill the collar joint.

• The use of solid 100mm blocks laid flat to create a wall thickness of either 190 or 215mm depending on block height used.

Guidance on the correct application of any of the alternatives specified should be sought from the Concrete Block Association or direct from manufacturers. Visit www.cba-blocks.org.uk for further details or email enquiries@cba-blocks.org.uk to register for a new guide to compliance with CDM, which will be published shortly. Alternatively, telephone the CBA helpline on 0116 253 6161.

16 August 2001

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