1 simple mistake could be causing expensive damage to your garden patio

When it comes to patios, a myriad of issues can wreak havoc on your slabs – from stubborn moss and algae to those annoying puddles that linger forever. An expert has now revealed a costly blunder that's slipping past most homeowners unnoticed.

This sneaky problem rears its ugly head months post-installation, turning your outdoor pride and joy into a pricey nightmare. We're talking about water where it shouldn't be, shifting and cracking slabs, unsightly algae, discolouration, and the worst offender – damp seeping into your home.

Dale Smith, the brains behind Fence Guru, warns this is a common tale in gardens far and wide, all thanks to one critical misstep.

READ MORE: Peace lilies 'flower like crazy' when watered with one food scrap weekly

READ MORE: Japanese Acers will turn bright red when watered with one thing in soil

The culprit? Neglecting to craft an adequate drainage slope during patio construction. It may seem trivial, but this error is the root of more long-term damage than any other patio-related oversight, reports the Express.

"Most people think a flat patio looks better, but that's exactly the problem," Dale points out. "Without the right slope, water has nowhere to go. It just sits there, and that's when your troubles begin."

• UK households with gardens face £5,000 fines for 'not keeping it tidy'
• Weeds will 'die off' in hours with one ingredient — and you won't need vinegar

He further notes: "The reason so many people get this wrong is that proper drainage planning isn't obvious, and it's not something you can see in photos or YouTube tutorials.

"DIY enthusiasts often concentrate on the aesthetic elements like pattern and materials, while contractors might skimp on the groundwork to cut corners on time."

A correctly fitted patio requires a minimum gradient of 1:80 sloping away from your house - that's approximately 12mm decline for every metre of patio breadth. It might seem minimal, but this subtle incline is what ensures water runs away from your dwelling rather than collecting on the surface.

"The slope should always direct water away from your house and towards a suitable drainage point," says Dale. "It needs to be consistent across the entire surface, not just in patches."

Beyond poor drainage creating instant issues, it can also trigger costly harm over time. Water that collects and freezes generates freeze-thaw fractures that crack slabs apart.

Water can also penetrate your home's foundations, resulting in dampness issues inside.

"I've seen cases where water damage from a poorly drained patio has cost homeowners thousands in structural repairs," Dale warns. "The patio itself might only be worth a few hundred pounds, but the damage it causes can be devastating."

Warning signs your patio has poor drainage

1. Persistent puddles: Water that remains on your patio for hours following rainfall is the most obvious warning signal.

"If you can still see standing water the next morning, your drainage is wrong," Dale notes.

2. Shifting or sinking slabs: When water accumulates beneath paving, it slowly erodes the foundation material.

This results in uneven surfaces and unstable slabs that wobble when you walk on them.

3. Moisture around door frames: If you're spotting damp patches near your back or patio doors, it's a tell-tale sign that water is heading towards your home rather than away from it.

4. Algae and moss growth: A constant state of wetness is the ideal breeding ground for greenery.

"If your patio looks like a pond after every shower, you've got a drainage issue," Dale points out.

When it comes to sorting out patio drainage woes, there's no need to fret if you're already facing problems – they can be sorted, albeit with more effort than nipping them in the bud initially.

Dale notes that sometimes adding drainage channels or extra outlets can make a difference. "Sometimes you can improve things by adding drainage channels or creating additional outlet points," he says.

For more serious situations, you might have to redo parts of the patio. "In severe cases, you might need to lift sections and re-lay them with proper falls."

Yet, the optimal moment to tackle drainage is during the design phase, before laying any paving stones. Dale advises planning your water flow and making sure you've got enough drainage spots.

He offers a strategy for ensuring effective drainage. "Start by working out the highest and lowest points of your space," he recommends.

Your patio should have a gradient from the high point to the low, leading excess water to a drain, grassy area, or a bed of gravel.