Inspection Chambers & Manhole Bases

We keep a range of manhole bases & inspection chambers to suit all needs. All manhole bases are kitemarked and BBA approved for use within the UK. Both are compatible with our 110mm or 160mm Drainage categories.


More Information on Inspection Chamber

category picture of a plastic inspection chamber

There’s a chance that your plumber recently told you that you need an inspection chamber as part of your drainage or sewerage system, but do you have any idea what it is?

What Is An Inspection Chamber?

An inspection chamber or a manhole is an access point for any pipework or sewer system underground. Contractors use it to carry out maintenance work, cleaning, or removing blockages, for example.

You cannot have underground pipework or sewer and miss inspection chambers, though.

People confuse manholes with inspection chambers often. A manhole allows for physical access, while an inspection chamber is used for inserting cameras or equipment into the spaces below. An inspection chamber is only used for inspections and minor repairs, not cleaning.

Are you wondering where to install an inspection chamber? It can be placed anywhere that a branch pipe connects with the main pipe of the drain or sewer.

It is a point that creates easy access to the rest of the branch for the camera. It also cuts down on the use of drain rods during the repair process. You wouldn't want your camera to travel a long distance inside the drainage pipe, as complications might arise.

The inspection chamber at the junction shortens the distance the camera has to move, giving you crucial information on the state of your pipes with little effort. You should also install another inspection chamber whenever the drainpipe's direction changes by more than 30 degrees or when the pipeline runs straight for more than 20 meters.

When installing inspection chambers, the rule of thumb is to have as many units as possible so that all the parts of the system are accessible with a drain rod. It will ensure that you reach blockages with drainpipes quickly.

When buying inspection chambers, you may note that some manufacturers offer a complete unit while others sell you the components separately on the website. If you are going to buy an inspection chamber as separate components, it is crucial to understand the different elements.

Inspection chambers are made up of three parts; base, side risers, and covers.

The parts have rubber seals at the join to prevent leakage of water and other substances. The base of the inspection chamber is closest to the drainpipes, and it's where the connection happens. Pipes have a diameter of either 110mm or 160mm. It has different inlets, so confirm the width from the manufacturer's website before making any purchase.

You can buy a base with various channels. If you find the bottom has more inlets than you need, a blanking lid works well.

The base joins to the riser. An inspection chamber's riser connects the base to the top. It is the mid-section of the unit.

The riser comes in different heights connecting the base with rubber seals. If the height extends further than the surface, you can cut it off with a saw so that the cover or lid sits in line with the surface. Corrugated exteriors make the whole process simpler.

The inspection chamber's cover, or the cap that goes on the surface of the inspection chamber, is the final piece. The cover is usually made of plastic and provides security against unwanted access and tampering. It is available in either a circular or square shape with different weight load classes.

The covers are also there to provide safety. The lids come with varying options of weight since they can be installed in high traffic areas.

How To Lower An Inspection Chamber

After purchasing your plastic inspection chamber and identifying a desirable installation point, you will still need some preparation before you can lower the inspection chamber.

The first step is to excavate the site and expose the drain piping system. You will need a proper layout of the entire drainage system so that you can unearth the right spot at the joints or somewhere along the way.

  • The size of the inspection chamber determines the amount of excavation.

  • The height determines the depth of the site.

  • The number of inlets determines the width of the manholes.

Laying the IC, or manhole, on a steep gradient is a challenge, especially using precast inspection chambers designed for flat surfaces. A steep slope, for example, would make the installation base lean at an unnatural angle, which makes fitting the riser and lid almost impossible.

It requires the use of bends to facilitate smooth transitions from the piping to the IC (and from the IC back to the tubing). Inspection chambers should be laid on gentle gradients (less than 30 degrees) to make work easier.

If that is not possible, then you will need to make a few modifications to your piping so that you can accommodate the changes. The primary methods are adjusting your pipe lengths and making use of the right bends. It will seamlessly connect to the IC base and maintain the right angle for the IC base.

How do you excavate for the installation of an IC into your sewer or drains?

It's a question some people ignore as they lay out their drainage system with manholes. If they did, it might factor in the future adjustments needed to accommodate a mainline adapt-a-valve inspection chamber, for example.

Excavating around the pipework is more than removing dirt or water and exposing both the crown and the collars. The pipe sections need to be cut to fit the mainline adapt-a-valve inspection chamber or a PVC inspection chamber, too.

A further 150-255mm is dug beneath the piping before installing the concrete bed that'll be laid for the Inspection chamber base, for example. As you are excavating, you can measure the size of the structures by temporarily lowering the mainline adapt-a-valve inspection chamber.

The excavated structures need to be wider than the IC chamber to allow room for working on the piping.

Once you complete the right size, you can use the chamber to mark the places that the pipeline will be cut. Ensure that there is no water flow before you start cutting. Drain the pipes and ensure the surface is also dry after cleaning.

If it’s a foul sewer, the sinks should remain unused for a couple of hours to prevent water flow. Consider installing a stopper at the first access chamber before the inspection space. You will need information on the layout of the drains with all the access points in the building.

The cuts on the pipe should be precise. You can use several tools, such as a pipe cutter, cut-off saw, or pipe-cutter chain to achieve the effect. Once you’ve cut the pipes and laid the concrete base, lower the inspection chamber.

How To Install An Inspection Chamber 

Before installing the chamber, ensure pipe cuts are smooth and clean. Stubs need to be squared off and thoroughly cleaned to prevent effluvia from causing a blockage. You don't want to be entering your manhole every few years.

If you need to re-cut the stubs, use a small angle grinder for precision. Use adapter couplings to attach the piping to the inspection chamber, with clean surfaces for water-tight bonding between the two structures. Proper surface cleaning will eradicate dirt from the surface of the stub and any debris inside the piping.

Find an adapter coupling suitable for your specific drains. Plastic tubing and clayware tend to have different widths. You can also choose adjustable and non-adjustable adaptor couplings, depending on the type of drains.

Clayware has thick walls, so the standard straight-through coupling is not possible. The adaptor coupling is installed on the stub but not tightened until the chamber is ready.

The inspection chamber usually has one of the inlets open, and the side inlets are closed using blanking plugs. It prevents water and effluvia from flowing out of the inspection chamber once installed. If you need more outlets, you can simply remove the blanking plugs and make use of the new inlets.

A thorough inspection of the new bay is vital against dirt or grit stuck on the socket or rubber rings around it.

Different cleaning techniques keep all the surfaces free from dust and water.

When building plastic manholes or other types of manholes, rocker pipes are used to connect the inspection chamber to the pipes. The rockers act as a bridge between the piping and the IC in the manhole.

The rocker pipes are meant to isolate the manhole structures from the rest of the building pipeline. It is best measured and installed on the chamber before it is lowered down the manhole.

Once the inspection chamber base sits on the concrete base and the rockers have been aligned, the coupling can now be done. It should only be hand-tightened to prevent the threads from stripping. If you are going to test the new IC fitting, a thorough surface inspection is critical to ensuring no dirt will hinder the joints.

Something as small as sand grains causes test failure and allows water to seep out. Once the base lies flat on the concrete base structures, though, it’s time to install the riser and the cover on the manhole.

The riser attaches to the base using a tongue-and-groove connector. The tongue faces upwards to prevent water spillage outside the chamber if there is a blockage. Depending on your inspection chamber unit, the cover may be rounded or square.

Check with your manufacturer before making the purchase. For either case, the inspection chamber cover clips into place without hassle. If your base were skew, you'd have problems covering the inspection chamber.

For deeper manholes, build a concrete wall around the inspection chamber base to take care of the ground pressure. Standard inspection chambers on regular drains use the back-filling of the excavated dirt or granular materials.

For more information on inspection chamber fittings or manholes, call Easy Merchant s at 01371 850120. Order a range of products for your drainage system or sewage line online from us, with secure payment and more expert advice.