Cover, seating, reducing and landing slabs

Cover Slabs

AG manufacture Type 2 heavy duty cover slabs suitable for manhole units.

These slabs come in a range of dimensions, however non-standard slabs can be designed and supplied to order. Cover slabs with special access holes can be supplied as made to order products.

Contact us for more information on our four metre diameter cover slabs.

Slabs in situ

More Information

AG operates a Quality Assurance Scheme to these standards to cover all aspects of production.

All units are supplied with suitable lifting points.

A precast concrete manhole is a strong, durable structure with its own inherent strength and does not require a concrete surround at standard depths.

All units are manufactured and tested in accordance with BS EN 1917: 2002 and BS 5911-3: 2002 which, in addition to specifying dimensional tolerances, etc., clearly defines all the performance tests necessary to ensure that the product will perform satisfactorily in service.

Minimum order quantities are required for certain products and sizes. Before placing an order, please speak to one of our sales teams – they’ll be happy to advise on this and any other product questions you may have. You can reach them on 0121 747 0202 in UK and on +44 (0)28 8778 8112 in Ireland.

Minimum order quantities are required for certain colours. Before placing an order, please speak to one of our sales teams – they’ll be happy to advise on this and any other product questions you may have.

You can reach them on:
UK: 0121 747 0202
Ireland: +44 (0)28 8778 8112

Seating Slabs

Cover frame seating rings are reinforced 70mm thick units manufactured to suit cover slabs with a 600 x 600, 675 x 675 and 750 x 600 opening.

These are used in place of engineering bricks to adjust the metal covers and frames to the required level.


  • They can be quickly and easily installed by semi-skilled labour.
  • There are fewer joints – reducing the likelihood of infiltration.
  • All concrete manhole units can be ordered from one source.
  • There is a reduced risk of on-site damage and pilferage.

Units are made in accordance with BS 5911-3: 2010 and in compliance with safety guidelines given in the HSE publication ‘Safe Work in Confined Spaces’.

Supporting Image

Reducing Slabs

Type 2 at various chamber sections.
Typical reducing slabs are supplied as Type 2 to suit the various chamber sections, from DN 1200 to DN 3000 and have a 1200mm circular access.

Supporting Image

Landing Slabs

For sections of DN 2100 and greater.

Landing slabs can be made to suit chamber sections of DN 2100 and greater, with an access opening to accommodate customer requirements.


Contact us for specification assistance and to check availability.


Cover Slabs

Ring diameter
Depth of cover slab (mm) Overall diameter of cover slab
Standard access sizes (mm) Weight for unit 675×675 access
600×600 675×675 750×600 750×750 1200×675
675 140 960 C C X X X 0.13 t
900 150  1160 C C X X X 0.16 t
1050 150 1240 E C X MTO X 0.28 t
1200 150 1400 E C E MTO X 0.40 t
1350 150 1570 E E E MTO MTO 0.54 t
1500 180 1770 E E E MTO MTO 0.90 t
1800 180 2100 E E E MTO MTO 1.43 t
2100 190 2500 E E E MTO MTO 2.18 t
2400 190 2760 E E E MTO MTO 2.60 t
2700 240 2980 E E E MTO MTO 4.00 t
3000 240 3300 E E E MTO MTO 4.70 t
3500 275 3850 MTO MTO MTO MTO MTO 7.40 t
4000 275 4500 MTO MTO MTO MTO MTO 10.50 t

Seating Slabs

Opening size Overall size Depth
mm mm mm
600×600 750×750 75
675×675 850×850 75
750×600 880×750 75

Reducing + Landing Slabs

For shaft / chamber section Approx. depth including DN1200 shaft ring Approx. overall diameter
DN mm mm
1500 250 1770
1800 250 2100
2100 250 2480
2400 250 2780
2700 250 3000
3000 250 3300

Case Studies

Featuring Slabs

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Why AG Professional?

Superior Quality

At AG we pride ourselves on superior quality and exceeding our customers’ expectations. Product quality is continuously being monitored and improved to provide the best quality products for our customers.

Expert Knowledge

The AG team have a wealth of experience and knowledge to share with our customers and clients. Our Technical Department is here to help – we pride ourselves in providing an unmatched level of support to make sure that all our customers get the best advice and the best possible solution for their projects. 

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At AG we believe in unrivalled support and will closely monitor and support every process from design concepts and specifications to fully indemnified engineered designs. From product supply and installation, to delivering samples, site meetings and technical support, AG will be with you on this journey.

Easy Spec

We offer a fast and easy specification service with our Sales and Specification department on hand to help with any queries. We have partnered with NBS Source which provides key specification information at your fingertips in platforms such as RIBA Product Selector and NBS Chorus. This delivers relevant product information, literature, case studies and certificates to our clients at a more effective level.

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Our team from our sales department to our despatch office work closely with customers to create a dedicated call off plan for your project. Detailed delivery planning will be scheduled around clients’ needs to ensure we provide the best customer service.

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AG have a strong commitment to the link between a sustainable environment and our local Community. In line with our Corporate Social Responsibility Strategy AG defines sustainability as the intrinsic balance between the social, economic and environmental aspects of our business operations. We have established a Net Zero Carbon team with the aim of reducing carbon emissions and are committed to producing low carbon products in our strategy.