Gardening & Landscaping

Advice Needed - Raised Patio Level with DPC & Air Bricks (Cotswold Stone Cottage)

Mathew 15/07/2025 - 3.22 PM

Hi all, I’m working on a project involving a Cotswold stone cottage with an L-shaped rear elevation and three sets of patio doors leading out onto a terrace. The existing patio and ramp are currently level with the internal floor, which unfortunately puts them above the DPC in one of the patio doors. The DPC itself is at two different heights - approx. 200mm below the floor level on one side and 320mm below on the other. Standard guidance says finished ground level should be 150mm below DPC, but if we were to follow that, we’d end up with a 400mm level drop, meaning we’d need to introduce steps - which we’re trying to avoid for accessibility reasons (in line with Part M regs). There are also air bricks along the elevation that are currently right at or just above ground level, which I know isn’t ideal. From what I understand, these should be at least 75mm above ground level to function properly. My questions are: Would building a flush patio with a 200mm gravel gap (with a French drain beneath it) be enough to mitigate risk of damp? Would this kind of drainage setup (gravel + fall away from building + channel drain) be considered acceptable even though we’re not achieving the 150mm drop below DPC? Is there a way to deal with the air bricks in this setup to ensure proper ventilation, or do they need to be relocated/raised? Would adding a soakaway be useful or necessary? Patio base would be a porous crushed aggregate, and the fall would direct water away from the property. Appreciate any thoughts or experiences from others who’ve worked on similar heritage builds or uneven DPC scenarios! Cheers, Mathew