Flooring grade blocks are inserted from above between the beams. Services can be easily accommodated by either cutting or omitting an infill block. Where an area on the layout drawings is shown as 'block-out', complete blocks are to be laid with a minimum of 100mm bearing on the adjacent support. All blocks should be cut using suitable mechanical means to leave a clean, vertical, square edged face.

Preparation

Initially, top soil and vegetable matter need to be removed to ensure a clear minimum airspace of 75mm between the ground and the underside of the flooring system. The foundations and walling are constructed in the normal way up to DPC level incorporating damp proof membranes and void ventilators at the required positions. Walls that support the ends of the beams and/or infill blocks are considered to be loadbearing and must be sound, true to line and level and constructed off suitable foundations.

Handling and storage

When delivered the beams should be stacked horizontally no more than 6 high of similar length on a hard, level, well drained surface. Each beam should be supported on suitable timber battens within 300mm of each end.

Great care should be taken to ensure that lifting points are located within 300mm of each end of the beams and lifted horizontally and not allowed to rotate whilst being handled. Units over 2.0m in length should not be lifted by forklift truck or any method which supports the beams at any points other than those stated above.

Installation

The floor beams are positioned in accordance with the layout drawings, perpendicular to the end supports, unless otherwise shown, with a nominal bearing of 100mm to each end (90mm minimum) when supported by brickwork/blockwork, and 75mm minimum bearing when supported by steelwork. Initial spacing is achieved by placing an infill block at each end in the correct orientation. The beams may be staggered at the internal walls and multiple beams may be necessary to support partition walls. Where this situation arises the void between the beam upstands must be completely filled with infill concrete as specified below. Beams should not be cut on site without the prior approval.

Where infill concrete is necessary it should, unless otherwise stated, be C25 using 10mm maximum coarse aggregate with a minimum cement content of 275kg/m3 as specified in BS 5328: Concrete.

It is recommended that slip blocks are used as infill to maintain coursing and to provide a uniform, level bearing to the extreme end and/or sides of infill blocks. Where beams are to be laid at 520mm centres, the slip blocks should be cut on site at the indentation on the unit and placed between the ends of the beams . All slip blocks should be bedded with a mortar bed above and below the unit.

Only where indicated on the layout drawings is the floor designed to support the self weight of non-loadbearing walls.

The beams and infill blocks should be cleaned after placing but prior to grouting and if necessary 'wetted' to prevent rapid water absorption from the grout. The grout should be 4:1 sharp sand:cement measured by volume adding enough water to produce a mix of plastic consistency. The grout must be evenly spread over the floor by brushing in the direction of the beams, and then at right angles to the span, ensuring that all joints are completely filled by the grout. When the grout has cured the floor becomes a rigid construction.

Where barrow and/or bogie runs are required, plywood or scaffold boards must be provided at all times at right angles to the span of the beams, or until the floor has been grouted and the grout allowed to cure, Under no circumstances should any beam or infill block be used if it is cracked, broken, has crumbling edges or appears to be faulty in any way.

Finishes

The floor is designed to receive a minimum of 50mm thick 1:3 cementsand screed (65mm when used with insulation) unless otherwise indicated. Where polystyrene, timber, or a floor is to be laid on the top surface of the floor, a 13mm (nominal) levelling screed is recommended to enable any slight differences in level occurring from construction and manufacturing tolerances to be eliminated..

 

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