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CPM Concrete Reducing Slab.
  • CPM Concrete Reducing Slab.

1500 x 1050mm Concrete Reducing Slab


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Product Details


Product Type: Concrete Reducing Slab
Model Type(s): Double Steps & IBR (Adaptable)
Chamber DN: 1500mm
Approx Overall DN: 1710mm
Reducing Section DN: 1050mm
Approx Maximum Depth: 250mm
Approx Weight: 1060kg

This reinforced concrete reducing slab is designed to reduce the size of the access point opening in concrete manhole chamber rings that have a 1500mm nominal diameter. Reducing the opening to 1050mm allows a manhole chamber construction to change from using 1500mm rings to 1050mm rings.

Product Features at a Glance:

  • 1050mm DN reducing section
  • Eccentric access positioning
  • Cast in lifting rungs
  • Fits flush to the chamber ring
  • Manufactured from reinforced concrete

This reducing slab is available in two model types:

IBR (Adaptable)  makes it suitable for use with either stepped or non-stepped manhole chambers. It is manufactured as non-stepped model, but has small indents/holes built in where a step iron can be inserted if/when needed at a later date. It is a flexible middle ground between having to choose whether steps are needed or not at the time of purchase.

Double Steps - makes it suitable for use with stepped manhole chamber rings with one double width step fitted in the reduced opening.

The Double Width Steps fitted in Stepped model are manufactured using virgin polypropylene copolymer plastic and reinforced with structural carbon steel. Polypropylene is used in the manufacture of car battery cases, which shows how resistant it is to concentrated sulphuric acid.

Key Features of Double Width Step Irons:

  • Bright colours ensure high visibility
  • No sharp edges
  • Extremely corrosion resistant
  • High tensile carbon steel
  • BS EN 13101, CE marked and Kitemarked

Customer Advice: For installations where the distance from ground level to the benching landing area is in excess of 3m, step irons are not permitted under United Utilities guidelines and a ladder must be installed. If unsure about the regulations, please contact our technical team for more advice or consult directly with United Utilities to confirm the relevant specifications for your project.

Concrete reducing slabs, are used in the main shaft construction of manhole chambers. Sitting on top of a larger chamber ring, they create an access point opening that allows the chamber construction to be continued with a smaller diameter chamber ring. Reducing slabs from CPM also benefit from cast in lifting rungs to aid in the safe positioning of the slabs onsite.

For manholes installed at shallow depths larger opening sizes are usually required, to permit standing/crouching space, but they are not always suitable for deeper depths. In a deep manhole installation, the lower manhole rings will be larger to accommodate the diameter of the pipe connecting to it and to meet the the required safe working space needed for man-entry. Once all minimum requirements are met however, the access shaft part of chamber can be "chimnied" up to a small ring size. Doing so reduces the hazard risk of the manhole should the cover ever be removed, and can help to reduce the overall project cost.

 Key Features of CPM Concrete Products:

  • Quality - Precast concrete drainage products are manufactured in accordance with the relevant BS EN 1916/7, BS EN 5911 and CE marked where applicable. Goods are certified by Quality Assessment under the Kitemark Scheme and ISO 9001:2015.
  • Sustainability - Concrete pipeline systems are one of the most sustainable options available, they are manufactured from responsibly sourced materials, and can be made using recycled aggregates and cement replacements.
  • Proven Strength - They have a proven life of over 120 years, in normal groundwater conditions, are not weakened by fire or moisture and do not lose their shape. They are resistant to DC4 and impacts such as jetting, so blockages can be cleared easily.
  • Installed Cost Savings - Precast concrete pipes are rigid structural elements that do not always require a full granular surround, saving time in bedding and compaction. Excavated material can be reused and imported granular material can be reduced to a minimum.
  • Durability - Due to the inherent strength and durability of the Marshalls CPM precast concrete products, they are highly abrasion and corrosion resistant and don't lose strength over time.
  • Design Flexibility - Precast concrete drainage products can be used for a number of purposes, including sewerage and sustainable urban drainage systems (SuDS) applications such as stormwater attenuation and storage.
  • Water Tightness - Concrete pipes and manholes are designed to be watertight and are tested to pressure levels equivalent to a 5 metre head of water.
  • Fire Resistant - Concrete is naturally fire resistant. 

Please Note: 
All dimensions and weights are approximate as concrete product dimensions can have slight variations due to their manufacturing process. Customers should ensure that lifting equipment has sufficient capacity to allow for variations. All images shown are used for illustration purposes only and may differ from the actual product supplied. 

16-20 working days
Product Type:
Manhole Reducing Slab
Marshalls CPM
Nominal Size: