Proper installation of underground drainage systems is crucial to ensure functionality and long-term durability. Here’s a guide to the essential steps involved in cutting, laying, joining pipes, and ensuring the system operates effectively.
Cutting and Joining Pipes
Cutting: Pipes can be cut using a fine-toothed saw. Ensure that the cut end is square.
Chamfering: After cutting, chamfer the pipe ends to remove sharp edges. This can be done with a medium file or rasp.
Cleaning: Clean the pipe ends of any dirt, swarf, or grit before installation.
Lubrication: Use SG800 lubricant on both the chamfered end of the pipe and the ring seal of the fitting.
Joining: Insert the pipe fully into the socket, then withdraw it by 10mm to allow for expansion or ground movement. Ensure the pipe is aligned squarely with the fitting for a secure joint.
Laying Drainage Pipes
Trench Size: Dig a trench 300mm wider than the pipe diameter. For 110mm pipes, the trench width should be 410mm.
Pipe Bed: The trench can be used as a pipe bed if the material is suitable (fine soil with no large stones). Typically, granular material like pea shingle (no larger than 10mm) is used.
Backfill: The trench’s sidefill and backfill should be composed of appropriate material (pea shingle or "as dug" material). At least 300mm of material should cover the pipe before mechanical compaction.
Protection: If the pipe is at risk of contact (e.g., from gardening activities), protect it with a paving slab cover.
Pipe Falls
Recommended Fall: For 110mm drainage pipes, a fall of 1 in 40 is recommended, especially for installations involving up to 5 houses, to maintain a self-cleansing flow.
Higher Flow Rates: If the system is expected to handle higher flow rates, the fall may be adjusted, but always refer to the Building Regulations (Document H) for guidance. If in doubt, consult your local authority.
Adjustable Bends
Connections to Above Ground Drainage
Compatibility: The underground drainage system is fully compatible with FloPlast’s Above Ground Soil and Vent System, allowing direct connections without adaptors.
Rainwater Pipe Connections: Use the D96 adaptor to connect rainwater pipes directly to the drainage system.
Waste Pipe Connections: For 32mm, 40mm, and 50mm waste pipes, use the D95 adaptor to connect to the drainage system.
Adaptors to Other Materials
Flexible Adaptors: The D102 and D103 flexible adaptors allow PVC drainage to be connected to a variety of materials, including clay, cast iron, and pitch fibre.
Cast Iron Connections: Use the SP140 adaptor to connect cast iron soil pipes to PVC drainage systems.
Testing Drains
Testing Requirement: All drainage installations should be tested in accordance with the relevant regulations and approved authority.
Guidance: Refer to the current edition of Building Regulations (Approved Document H) for specific testing requirements.
By following these basic principles, you ensure that your underground drainage system is installed correctly, with optimal performance and durability.
