Concrete Pipes

Pipe bedding & Material Calculator

This calculator is designed to help you estimate the material cost (pipe bedding, infill material and pipes) for installation pipes using different bedding designs. The calculator compares four classes of pipe bedding for rigid concrete pipes and the single pipe bedding class usually used for flexible (plastic) pipes.

About Pipe Bedding Classes:

The load bearing capacity of an installed pipeline relates directly to the construction of the bedding which is intended to level out any irregularities in the formation, and provide uniform support around and along the length of the pipe barrel. The strength of an installed pipeline depends on a combination of the strength of pipe and the class of bedding. The selection of the pipe bedding class is influenced by many factors, which include the nature of the ground, the loads acting on the pipeline in the trench, the strength of the pipe, and the local cost and availability of the pipe bedding material.

Click on illustrations to enlarge

In situations where imported granular material is expensive and where supervision of site work cannot be guaranteed, it is preferable to specify a lower class of bedding with a higher pipe strength. This is the main reason why material costs for installing concrete and plastic pipes are different. Class B is based on 180⁰ granular bedding with selected backfill material; Class S requires full 360⁰ granular bedding and therefore costs more. Additional costs of bedding material with more Aggregates Levy paid per metre run of pipe laid, costs of excavated material transported from site, etc.)

The cost breakdown is calculated per metre run of pipe. To use the calculator you will need the following information:

  • Nominal diameter (DN) of the pipe
  • Cost of pipe (per metre run) – including gaskets, connectors etc. If not integral to pipe.
  • Cost of transporting excavated material from site and disposal cost to landfill (per tonne).
  • Unit cost of bedding used (per tonne).
  • Bulk density of excavated material and imported granular bedding (tonnes per cubic metre), if known. Default values of 2.0 for excavated material and 2.2 for bedding are assumed.

About British Precast Drainage Association

The British Precast Drainage Association (BPDA) is formed from the integration of the Concrete Pipeline Systems Association (CPSA) and the Box Culvert Association (BCA) and takes its place as one of the specialist product groups within the British Precast Concrete Federation.

British Precast Drainage Association member companies account for the majority of precast concrete drainage products manufactured in Great Britain and Northern Ireland.

All British Precast Drainage Association members have signed-up to the exacting standards of the British Precast Raising the Bar programme. Designed to ensure that all members achieve minimum standards of health & safety and meet sustainability targets whilst providing customers with exceptional technical support and first class customer service.

In addition, British Precast Drainage Association’s associate members supply essential equipment and materials used in the production of concrete pipes and manholes.

Taken from BS9295:2010 Guide to the structural design of buried pipelines: Design Considerations

Concrete Pipe
Plastic Pipe
Bedding Class
Input Class S Class B Class F Class N Class S
Pipe Diameter (mm) 225 225 225 225
Cost of Pipe (£/m)
Cost of material taken off site to landfill (£/T)
Bulk Density Excavated Material (T/m3) 2.0 2.0 2.0 2.0
Unit cost of bedding
Bulk Density Imported Bedding (T/m3) 2.2 2.2 2.2 2.2


The nominal diameter of a pipe is generally determined by its internal diameter. The calculator compares the nominal diameter of a concrete pipe with the equivalent nominal diameter of a plastic pipe. Where the equivalent nominal diameter of a plastic pipe is not the same numeric value as the concrete pipe, the calculator will up-size the plastic pipe to the next available nominal diameter, thus ensuring that the hydraulic design is not compromised.

The figure used for outside diameter (OD) is based on the mathematical mean for a range of different pipe manufacturers standard products. For concrete pipes, the range is based on BPDA member companies. For plastic pipes, the mathematical mean includes both solid wall and structured wall pipes.

Trench width is based on the medium trench widths as per TRRL Simplified Tables.

Bespoke products fabricated to other sizes may be available on request, but have not been included in the calculator. Contact BPDA member companies for details.