A Guide to Beam and Block Floor Installation

Beam and Block flooring is still the most popular form of flooring for new build domestic construction. Comprising of inverted T-beams made from pre-stressed concrete and concrete infill blocks, the floor can be laid quickly and provides a working platform for follow-on trades. This type of concrete floor requires little groundwork preparation and sits on a DPC on the internal skin, as such it is one of the most cost-effective types of precast concrete flooring for new builds.

Longley’s Beam and block floors can be installed with minimum fuss and maximum effectiveness. They provide an immediate, safe working platform that is rot proof and fire resistant. Problems associated with frost, ground movement or clay heave and shrinkage are completely eliminated, and they are also squeak free. Services passing through the floor can easily be accommodated between the beams by removing blocks after final positioning of the services.

Our beams are manufactured with C60 (60N/mm2 at 28 days) concrete, prestressed by means of 5 mm indented steel wire. Longley beams are manufactured in fixed moulds within an enclosed factory environment, giving them a superior finish and dimensional tolerance.

Beam and block floor

Beam and Block Floor Installation Instructions

Beam and block flooring is easy to install with the following guidance.

Installing Ground Floors

A minimum void of 150 mm must be provided between the soffit of the floor and the solum and a continuous damp proof course must be laid beneath the beam ends.

Infill blocks to be aerated, aggregate or concrete, 440 x 215 x 100 mm. Minimum compressive strength of 3.5 N/mm² or 7.0 N/mm² with a traverse load capacity of 3.5 kN on a 420 mm span. 

For garage floor applications, blocks with 7.0N/mm2 compressive strength should be used. 

To seal the joints, the whole floor should be grouted with a nominal 3:1 sharp sand/cement mix as soon as possible after fixing the floor joists and blocks. Brushing the grout over the floor with a stiff broom after the surface has been well ‘wetted’. Ensure the grout penetrates the joints to provide a rigid construction. 

Floor finishes applied directly to the grouted floor can be chipboard, reinforced concrete on insulation, directly bonded screed or asphalt.

Installing Upper Floors

Infill blocks to be aggregate or concrete, 440 x 215 x 100 mm. Minimum compressive strength of 3.5 N/mm² or 7.0 N/mm² with a transverse load capacity of 3.5 kN on a 420 mm span.

When the floor separates a dwelling from another dwelling, it must comply with Building Regulations Approved Document E. This can be done by building to Robust Detail E-FC-6 or E-FC-7. 

A plasterboard ceiling can easily be installed using metal clips, 50 x 50 mm timber battens and plasterboard; this inevitably increases the fire resistance.  

The floor when constructed with a plasterboard ceiling provides up to 1 hour fire resistance. A floor which comprises of the Longley widened beams constructed as above provides up to 1½ hour fire resistance. 

Where blocks are built in to loadbearing walls, their compressive strength must not be less than that of the blocks used in the wall construction.

For any other beam and block floor installation queries, our estimating team provide plans for beam and block projects, detailing the number and location of beams. Enquire here.