Beam & Block Floors 155mm, 220mm

 beam and block flooringMexboro floor beams 

Beam and Block Floor System

beam and block precast flooring systemConsisting of pre-stressed concrete beams with standard building blocks laid between, Mexboro’s Beam and Block Flooring systems provide an economical, quick and flexible choice with the following benefits:  

Minimum site preparation – just remove topsoil and vegetation to provide a minimum 75mm void or 150mm for clay between underside of floor and ground surface.  

No compaction or back-fill – no ground-heave problems.  

Not weather dependent  – construction can begin on delivery, whatever the weather conditions.  

Easy handling – blocks and beams can be easily handled by forklifts or cranes and smaller lengths manually handled (subject to risk assessment).  

Speed of installation – One man can lay 60 square metres in a day and is not adversely effected by bad weather.  

Savings in foundations – internal partition walls can often be carried by double or triple beams.  

Improved heat and sound insulation.  

Draught proof, rot proof, fire resistant and very durable.  

Accurate costings – can be made from the design stage.  

Specify Mexboro 155 or 220 Beam floor as manufacturers’ instructions, and Mexboro will accept full design responsibility supplying design layout drawings, technical details and calculations for Building Regulations approval.  

Early working Platforms – when floor is laid and brush grouted it can be used as a working platform within its design limits. (Care must be taken to avoid overloading floor when blocking out).  

Design of Beam

Beams generally have been designed in accordance with the Code of Practice BS 8110:1985 and are checked for comliance on each specific job undertaken. 

Design of Infill Blocks

All infill blocks must be able to satisfy a 3.5N/mm2 transverse load test.  


Using a single block at each end, the beams are spaced as shown on the drawings.  Slip tiles are bedded as required and the remainder of the infil blocks laid. A sand a cement grout mix is then brushed over the whole slab and worked well into the joints. 


Screed – a 50mm sand/cement screed over the basic construction gives the ideal surface for tiling etc.. 

Traditional – timber battens can be laid over the basic construction at appropriate centres for standard T & G boarding or similar. 

Insulated – for ground floors etc. 20mm expanded polystyrene sheets can be laid over the basic construction, taking account of the camber, then covered with a 1000g polythene vapour barrier and overlaid with T & G chipboard sheets. 

Garage Floors – use a 50mm topping of Grade 30 Concrete using 10mm aggregate and incorporating a A98 or A142 MESH. 

Fire Resistance

Without any applied ceiling finish the completed construction as described above (using a 1950kg/m3 block) will provide for a one hour fire resistance. A suspended ceiling will improve this figure. 

Sound Resistance

The basic construction has a minimum mass of 242kg/m2 (using a 1950kg/m3block) without any finishing screed.  This rises to 365kg/m2 using: 

55mm screed on the 530/540 c/s system.

50mm screed on the 420/430 c/s system.  

50mm screed on the 305/315 c/s system.  

50mm screed on the 440/465 c/s system.  

50mm screed on the 138/152 c/s system.  

These values show the appropriate deemed to satisfy floor construction to be chosen from the Building Regulations complying with Part II or Part III of Schedule 12 as required.


All pre-stressed concrete systems have an inherent upward camber along the length of the beams. Every effort is made to keep this to a minimum but it is difficult to control precisely. Suitable allowances should therefore be made in top and soffit finishes to accommodate this.  

*The sound and fire protection will be less for light weight blocks than dense blocks.
* Light weight blocks are not suitable for garage or industrial applications.  

Mexboro Table of ‘U’ Values w/m2k  

Floor Construction – Finish: 18mm Chipboard on 25mm Polystyrene. Unit Load = 15kn/m2

U values table

U Values Table for Beam & Block Floor

 British Standards Compliance

Beams are cast by the ‘Longline’ pre stressing method, using materials to appropriate British Standards: Cements to BS 12: 1978;  Aggregates to BS882:1983; and Pre-Stress Wire to BS 5896.

pre-stressed beams with BS compliance

Pre-Stressed Floor Beams

 Span Tables for 155mm Floor Beam System

Span Table for 155mm Floor Beam System

Span Table for 155mm Floor Beam

 Span Tables for 220mm Floor Beam System

Load Span Tables for 220mm Floor Beam System

 Accoustic Floors – Robust Details

* Sections 7, 8 and 9 (noted below) are in the Robust Details Handbook.  For the latest details and additional information please go to:

Roubst Details for Accoustic Floors E-FC-6

Roubst Details for Accoustic Floors E-FC-6

Robust Details for Accoustic Floors E-FC-7

Robust Details for Accoustic Floors E-FC-7

For further details please download our flooring brochure:

Beam and Block Flooring Brochure

Mexboro Lorries Old and New

Top of page ^^