Support

Use the CD 499 Reducer. This fits under all our polypropylene 450mm diameter inspection covers and will reduce the clear opening to 350mm, thus complying with building regulations.

We recommend using our CD 452 Polypropylene cover & frame, which complies with Part H of the Building Regulations 2010.

Clark-Drain recommends B125 covers as a minimum specification for driveway use. A15 covers are for use in pedestrian areas only and should not be used in driveways. Further detailed advice can be found in our catalogues.

All manhole cover sizes are measured by the clear opening inside the frame as this is the only true constant between manufacturer's designs.

Forklift trucks generally have smaller diameter tyres, with a smaller contact area, than road going vehicles.

Calculations show that they apply at least 4 times the load of a 10 Tonne lorry, along with extra dynamic forces due to solid tyres, limited suspension etc.

Clark-Drain recommends the use of our forklift rated covers for use in all forklift loading areas.

This might happen if our installation guidelines have not been followed and the block paviors surrounding the frame were laid on sand only rather than mortar. In this scenario, it is possible for the sand under the paviors and around the frame to work loose, thus reducing support and potentially allowing the cover and frame to bow. Provided the problem is addressed early enough, and assuming that no abnormally heavy vehicles have driven over the cover, it should be possible to effect a repair. Remove the blocks and the cover & frame and reinstall them all on a bed of weak-mix mortar.

Refer to our installation guides for further information.