Block paving

Standard construction practices dictate the installation of a dedicated stormwater management system to mitigate the risk of foundation undermining and public right-of-way flooding. A technically sound solution involves integrating a sub-surface French drain (utilizing a perforated PVC/HDPE pipe wrapped in geotextile fabric and embedded in clean crushed stone) beneath the sub-base layer. This design ensures efficient groundwater redirection and dissipation during peak precipitation events. Implementing this sub-surface drainage control is highly recommended for long-term structural integrity, and we request a formal variation order (change order) outlining the additional costs for this scope of work."

If the patio has a proper fall away from the house and the water can drain naturally into the flower beds without causing pooling or affecting the property, then drains aren’t always necessary. However, if the area is being sealed, surface water will run off more quickly, so it’s important the slope is sufficient and the flower beds can cope with the extra water. If there’s any doubt, I’d recommend installing drainage now rather than having to add it later.

It may be acceptable if the surface has a proper fall and all rainwater drains safely into your own flower beds without pooling or running towards the house or neighbouring property. However, once the surface is sealed, less water will soak through it and more water may run off. I would make sure the builder tests the falls before finishing. If there is any risk of water collecting near the building, a channel drain should be installed rather than relying only on the flower beds.