Experts in Concrete Patio installation
If rainwater flows from your patio toward your home, it can lead to damp problems, foundation damage, and pooling near walls. In UK gardens where weather is often unpredictable and drainage systems are overlooked, this issue is more common than you might think.
This guide explains why patios drain toward houses, what solutions you can put in place, and how to ensure your outdoor space protects, rather than threatens, your property.
Poor drainage isn’t always obvious during dry months, but when rain hits, the flow direction becomes clear. Here are the most common reasons patios slope the wrong way, and the long-term effects if left unaddressed.
Every patio should be built with a gentle slope, typically 1:60, slanting away from the house. If the slope is level or tilted toward the building, water naturally runs in the wrong direction. This is often due to poor workmanship or rushed installations, where slope was measured incorrectly or ignored completely. Over time, this causes pooling near foundations, leads to damp issues inside, and can even undermine the sub-base if left untreated.
Even if your patio was installed correctly, the ground underneath can shift over time. Sub-base movement, especially in areas with clay-heavy soil or poor compaction, causes parts of the patio to sink, often closest to the house where drainage was never intended. Once this happens, water begins to pool or run back toward walls and doors, requiring intervention to rebalance the surface or improve runoff redirection.
A slope alone isn’t always enough. Without drainage channels, gravel strips, or soakaways, rainwater can collect along edges or run toward the lowest point, often the house. If your patio butts up to the brickwork without any kind of buffer or drainage break, there’s nowhere for excess water to go but back inside the property. This is especially common in older installations or garden renovations where drainage wasn’t considered part of the design.
If your patio was built with drainage but you’re still seeing pooling, the existing system may be blocked, too shallow, or wrongly positioned. A common problem is channel drains filled with dirt, leaves, or algae that no longer allow water to flow freely. Without routine maintenance, even a well-designed drainage setup can become overwhelmed during heavy downpours, causing water to spill over toward your property.
In sloped gardens, rainwater doesn’t just fall on the patio, it also runs off lawns, raised beds, and hardscaped areas. If these higher areas direct water onto the patio without clear runoff channels, it increases the volume flowing toward your house. Combined with poor slope and no drainage, this dramatically raises the risk of water entering the building or undermining the patio’s substructure.
Water likely drains toward the house due to poor slope, an uneven patio surface, or a lack of proper drainage. Over time, this can lead to damp issues and structural damage if not corrected.
A patio should have a minimum fall of 1:60, meaning for every 60 units of length, it should drop 1 unit away from the house. This ensures rainwater runs off instead of pooling near walls.
Yes. Surface drains like channel drains or gravel strips can be retrofitted to an existing patio. In some cases, lifting and re-laying slabs may be needed to integrate the drainage properly.
Ensure your patio is sloped away from the property, and add surface drainage like channel drains or gravel strips. Combine these with downpipe management and soakaways to redirect water safely.
Generally no, unless your changes affect the property boundary, listed buildings, or involve large soakaways. For most UK homes, adding drainage or re-sloping patios is allowed under permitted development.
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