Soakaway Crates - Deep

Soakaways for residential properties usually fall under Building Regulations Part H, which covers drainage and waste disposal. A soil percolation test is normally required to confirm the ground is suitable — sandy and loamy soils typically pass, while clay and filled ground often don't. Planning permission may also apply if your project involves more than 5 m² of new impermeable surface, such as a driveway or patio. Check with your local authority before installation.

If soakaway crates are purchased flat-packed, they will need to be assembled. The only tool required for this is a rubber mallet to lightly hammer the lugs of the small plates into the rows of holes on the large plate, and then the same for the remaining three large plates so that the crate structure is complete. Assembling a full cubic metre crate takes less than 10 minutes and should be done on a flat surface.

Once assembled, soakaway crates should be placed into a dug-out hole in the ground that is lined with a geotextile membrane. The membrane should then be wrapped around the crates before the hole is backfilled with a layer of sand or gravel followed by a layer of soil.

When excavating a hole for a soakaway crate, the depth should be at a minimum 450mm deeper than the height of the crate you are installing. This will allow for a 150mm base layer of sand to be laid beneath the crate, and then 150mm of sand to be laid on top of the crate along with a 150mm layer of soil. The width and length of the excavated hole should be 300mm more than the dimensions of the crate, to allow for a 150mm backfill on all sides.

Correctly installed soakaway crates can last for decades without needing to be replaced.

The best way to prevent blockages is to install a prefilter before the soakaway crate in the drainage system. Silt traps or catchpit chambers are the most popular options for this, as they will catch soil and sediment and stop them from entering the soakaway crate.