Polypropylene Square to Round Chamber Cover for Tarmac, Grass and Gravel
The CD300 is a square to round solid top cover for round domestic inspection chambers. Clark Drain moulds this 300mm drain cover from Grade AP9 polypropylene, with a square frame that sits flush in tarmac, grass or gravel over a circular riser below.
Specifications
| Product code | CD300 |
| Product type | Square to round solid top cover |
| Material | Polypropylene Grade AP9 |
| Clear opening | 220 to 300mm diameter |
| Overall size | 438 x 438mm |
| Depth | 97mm overall, 37mm frame |
| Load rating | 35kN, held for 30 seconds (domestic driveway) |
| Weight | 4kg |
| Fixings | 4 locking screws supplied |
Key Design Features
A stepped spigot on the underside acts as a reducer, so the one cover fits Clark Drain U353 and U355 risers and most other manufacturers’ 220 to 300mm risers. The square frame can be rotated to match the direction of paving, and four locking screws hold the cover in the frame.
Benefits
- One cover fits a range of riser diameters, reducing the stock needed on site.
- Square frame aligns with paving edges and surface finishes.
- Locking screws stop the cover lifting or being removed by hand.
Applications
Use the CD300 Square To Round Solid Top Cover over round inspection chambers in domestic driveways, gardens and landscaped areas finished in tarmac, grass or gravel. Clark Drain rates the 35kN load for domestic driveways, so specify a higher rated cover for commercial or heavier traffic.
Other Sizes & Options
The CD456 450mm version covers the larger 450mm chamber. The Clark Drain range lists recessed block paving covers and reducing rings.
Contact Us
For help matching a cover to your chamber riser, contact Castings Drainage for technical advice and UK-wide supply.




