Do i need a channel drain ?

themoneyguy

Hi

Took on a DIY project of raised patio at the rear of my house. The elevation of patio is 600cm so pretty high. The finish will be 150mm below dpc. I am paving with granite paving slabs which are permeable. The fall will be away from house. So.... do i need a channel drain at threshold of property ? Or will all water fall away and just drain into the paving. Logic makes me think there will be no pooling due to height of raised patio, fall and the fact that granite paving will allow the water to run through. Due to tackle at the weekend so a serious question 🤔

Thanks in advance for advice.

whizbang

Not sure Ganite is permeable…

The issue is if water is flowing under slabs, at that height it will quite likely cause some erosion of the sub base causing sagging and unevenness.

If not draining through the surface, then it depends on how good the surrounding surface/soil is at absorbing water.

standardg60

No patio slabs are permeable enough to drain it and granite should be laid in concrete anyway.

What's at the end of the fall? Is there a drop into the garden or is meeting higher ground?

If a drop no need for drainage channel, if there isn't there is.