Adoptable and non-adoptable inspection chambers to suit all UK twinwall systems, ultrarib and polysewer

Inspection chambers play an integral part in providing access to and ensuring the safety of underground drainage systems. This range of inspection chambers are designed to be compatible with all UK twinwall pipe systems and surface water systems. They can also be adapted to take structured wall drainage, such as Ultrarib, and other pipe systems.

This range is classed as non entry access and so is limited to 3 metre inverts in adoptable application as stipulated in (Sewers for Adoption 2013 Section B2.2-Access).

Inspection Chamber Questions?

So you know you need to install an inspection chamber but you have a few questions, such as what’s its actual purpose and what’s the difference between adoptable and non-adoptable inspection chambers.

We’ve put together a beginners guide to inspection chambers that should answer any questions you may have.

Twinwall compatible

Designed to be compatible with all UK twinwall pipe systems and can be adapted to take ultrarib too.


Our chambers are manufactured using high strength polyethylene and can be installed in minimum granular surround.


Our chambers are water tested and can be supplied with seals to give a fully watertight chamber.


We supply two different types of models to suit your requirements:

Straight Channel:

An inspection chamber with a straight channel through the base.

Available in depths of 1m and 1.5m, with options for connection to twinwall pipe in the following sizes:

  • 150mm
  • 225mm
  • 300mm

Deep catchpit:

A 1 metre inspection chamber with a 500mm deep catchpit for silt and sand under the pipe work invert. This will give 250 litres of solids retention below the pipe work.

Available for connection to twinwall pipe in the following sizes:

  • 150mm
  • 225mm
  • 300mm

To view more details, click here to view our brochure.


Both our models come with the option of 1, 1.5 or 2 metre access shaft extension/risers.

Access extension risers
These extension risers can be used to increase the invert above 1 metre. If above 1.2 metres then the access cover needs to be restricted to 350mm for safety, again stipulated in Sewers for adoption.

Access reducer cap
We can also supply a sealed cap to fit over the riser. This has a 350mm opening that will accomodate most access covers of this size.

Access covers
We supply a range of access covers, from Pedestrian Duty to D400 Heavy Duty.

320mm Riser

320mm Riser

(£5.00 ex VAT)

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450mm Riser

450mm Riser

(£9.03 ex VAT)

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