Why Your New Patio is Flooding Your Airbricks
Is your new patio causing damp inside the house? Discover why poor leveling bridges the DPC, floods your airbricks, and how proper Aco drainage fixes it.
I get called to these disasters all winter. Someone drops ten grand on a massive new porcelain patio. It looks mint in the summer. Then November hits, the heavy rain starts, and suddenly the wallpaper inside their living room is peeling off at the skirting boards.
They think the house has a leak. It doesn't. The bloke who laid the paving just turned their garden into a moat.
Here is exactly how cowboy builders flood your house, and the building regs they ignore to do it.
Chuck the Spirit Level
A patio should never actually be flat. If you lay paving perfectly level, the rainwater just sits there and forms massive puddles. You need a proper fall.
Building regs dictate a 1-in-60 fall pointing directly away from the property. It’s invisible to the eye, but it forces the rain to run off into the garden soil.
Cheap landscapers don't own calibrated laser levels. They just guess the slope using a battered old spirit level. They get it wrong, and you end up with a patio sloping towards house. Every single drop of rain that hits your new stone runs straight backwards and pools right against your exterior brickwork.
Burying the DPC
It gets worse. Your house has a Damp Proof Course (DPC). It’s a plastic membrane built into the brickwork to stop ground moisture soaking up your walls. Just underneath that, you have airbricks to ventilate your floorboards so they don't rot.
By law, any new paving must sit a minimum of 150mm below that DPC line.
Cowboys hate digging. Instead of hiring a skip and removing the old ground, they just dump a thick mortar bed over your existing dirt and lay the new stone right on top. They raise the ground level so high they end up bridging the DPC entirely. Half the time, they pave right over the top of the airbricks.
When the patio slopes the wrong way, the rain pours straight into those blocked airbricks and floods the void under your floor. You get severe damp from new patio slabs, and you end up ripping up your interior carpets to pay for airbrick flooding repair. It is an absolute nightmare to fix.
Aco Drains and Lasers
We don't mess around with water.
When we handle patio drainage Dorset, the diggers come in first. We drop the ground level completely so we are miles below your DPC. We set up a laser level to guarantee a perfect, consistent fall pushing the water out to the lawn.
If we absolutely have to pave flush near a property threshold—like matching the height of modern bifold doors—we install heavy-duty linear Aco drainage channels directly against the house. We pipe that channel straight into a proper soakaway. The water hits the grid and vanishes before it ever touches your brickwork.
Stop letting amateurs drown your house.
Pop down and see the lads at 78 Alma Rd, Bournemouth BH9 1AN, UK, or ring the site phone on 07835 390845. We’ll show you how we set the laser levels up on site.
