How to Stop Rats From Getting Under Your Decking

A practical guide for UK homeowners on rat prevention, the right exclusion mesh, and smart decking design

Discovering rats under your decking is one of those problems that catches homeowners completely off guard. One day you're enjoying your garden, the next you're hearing scratching beneath your feet and spotting signs of burrowing along the deck edges.

At Duralive Decking, we're asked about this more often than you might expect — particularly from homeowners across Merseyside and Cheshire who are either planning new composite decking or upgrading an existing timber deck. And the question is almost always the same:

"How do I stop rats from nesting under my decking — and what's the right way to do it?"

The answer involves a combination of removing what draws rats in, installing the right physical barrier, and making the space under your deck less appealing long-term. This guide walks you through all of it — including exactly how to stop rats from getting under decking for good.

Why Rats Get Under Your Decking — and How to Stop Them

Understanding what brings rats to your decking is the most important starting point — because prevention only works if you're addressing the right causes.

Decking itself doesn't "attract" rats the way food does. But the sheltered void beneath a deck is exactly what rats look for: cover, warmth, concealment, and a safe place to move between locations. If food and water are also nearby, a deck can quickly become a regular stopping point — and eventually, a nesting site.

In gardens across the UK, the most common accidental "rat feeders" are spilled bird seed beneath hanging feeders, pet food left outside overnight, overflowing bins or compost heaps close to the deck, and warm compost bins full of food scraps.

Norway rats — the most common species in UK gardens — are particularly fond of concealed burrows. Typical burrow entrances are just a few inches across, and burrows often sit under 18 inches deep, with multiple entry and exit points. Along deck edges, foundations, and beneath debris are their preferred spots. The key principle: your deck is the cover. Remove the food, the water, and the harborage, and you've already made the problem much less likely.

Removing What Draws Rats In: Food, Water and Cover

Before you install any physical barrier, it's worth addressing the environmental factors that make your garden attractive to rats. The most durable solutions combine proofing (exclusion) with hygiene and harborage removal — this is also the approach recommended by UK pest control guidance as a longer-term alternative to relying on rodenticides.

Practical steps to reduce rat attraction:

• Move bird feeders well away from the decking. Fallen seed is one of the most consistent "invisible feeders" in UK gardens — particularly in Merseyside and Cheshire where garden birds are popular. Switch to no-mess mixes and use a tray beneath feeders to catch spills.

• Don't leave pet food outside overnight. Even a single bowl of pet food is enough to establish regular rat activity in the area.

• Secure bins and compost heaps. Use lidded bins and consider protecting compost heaps with wire mesh if they're close to the deck.

• Clear debris and vegetation around the deck perimeter. Overgrown areas, wood piles, and dense planting give rats the cover they need to move around undetected. Maintaining a clear, open perimeter makes rat activity much more exposed.

• Remove wood piles, bricks, or garden waste stored beneath or near the deck — these are common nesting materials and should be relocated away from the structure.

• Important note: ultrasonic and electromagnetic "repellers" are widely available but are not recommended as reliable solutions by credible pest control guidance. Physical exclusion combined with hygiene measures is the method that consistently holds up over time.

  
  

How to Install Mesh That Actually Works

The most common failure point in decking exclusion isn't the mesh itself — it's how it's installed. Rats don't typically push through mesh directly. They dig under it, or find gaps where the mesh meets the frame or the ground. There are two well-supported installation methods that consistently appear across credible pest exclusion and construction guidance:

Method 1: The Vertical Skirt with Buried Depth

The TDCA recommends fitting mesh 300 mm vertically (around 12 inches) into the ground around the deck edge where it meets the ground. This depth is consistent with exclusion barrier guidance from other pest control and construction sources and provides sufficient resistance against burrowing. The top of the mesh should be secured tightly to the deck frame to eliminate any gap at the junction between the mesh and structure.

Method 2: The L-Shaped Buried Apron

A particularly effective alternative — especially where digging a deep trench all the way around is impractical — is the L-shaped curtain barrier. Fix the mesh vertically against the deck frame, extending it down to ground level. At the base, bend the mesh outward horizontally by approximately 150 mm (6 inches). Stake the horizontal section flat and cover it with soil or gravel. The buried apron stops rats digging under the base of the vertical section — the extra effort required to get past the buried shelf means this approach often achieves strong anti-dig performance without needing an extremely deep trench the whole way around.

Critical Warning: Don't Seal Animals In

Multiple rodent-proofing sources are clear on this point: do not seal access points until you know what's using them and have a control plan in place. Sealing active burrows or gaps while rats are present can increase damage inside the void, prompt additional gnawing attempts, and make the problem significantly harder to resolve. If there are signs of active infestation — fresh droppings, soil disturbance, gnawing damage — deal with the rats first, then install the exclusion barrier.

The Right Exclusion Mesh: Size, Material and Gauge

What Mesh Size Do You Need?

The Timber Decking and Cladding Association (TDCA) specifically recommends welded mesh with a 5 mm hole pattern installed around the deck edge to prevent rat access. Public health guidance commonly cites 1/4 inch (approximately 6 mm) as the benchmark for excluding both rats and mice. Some sources use 1/2 inch (12-13 mm) for rats alone — but in practice, gardens often have both species, and it is common for homeowners to confuse the two. UK pest guidance also notes that rats may only need a gap of around 15 mm to access a structure, which is much tighter than most people expect.

Our recommendation: use 5 mm or 1/4-inch (6 mm) welded mesh for decking exclusion. This is effective against both rats and mice, aligns with TDCA guidance, and leaves no ambiguity about coverage.

Wire Type, Gauge and Corrosion Resistance

Hole size is only part of the equation. In a garden environment — particularly in the wet conditions common across Merseyside and Cheshire — the wire itself also needs to last. Key specifications to look for: welded at each joint (not twisted), as welded mesh holds its shape under pressure and doesn't unravel if a single strand is damaged; galvanised after welding for the best corrosion resistance (wire wool, by contrast, corrodes surprisingly quickly in damp conditions and is only a short-term measure); 16-19 gauge wire, which is widely recommended for demanding exclusion applications and costs more upfront but resists gnawing and lasts significantly longer; and avoid aluminium or plastic screening, which are treated as temporary deterrents only — rats will defeat these over time, particularly where they can find a rough surface or exposed edge to gnaw.

Keeping Airflow While Keeping Rats Out

When homeowners skirt a deck tightly to exclude rodents, there's a risk of accidentally reducing airflow and creating a moisture problem beneath the boards — which is particularly damaging for composite decking. In the damp climate of Merseyside and Cheshire, this is a genuine concern that needs to be designed out from the start, not addressed after the fact.

Composite decking installation guidance is clear: adequate, unobstructed airflow is essential beneath the decked area. Key requirements include a minimum ground clearance of 50 mm beneath the decking structure, adequate drainage beneath the deck — ideally with weed-control membrane and gravel or chippings — and where ventilation is limited by design, a minimum 47 mm airflow gap through joist arrangement. The practical solution that satisfies both requirements is using welded mesh as the vented skirt: air can still circulate freely through the mesh apertures, while rats face a solid physical barrier they cannot defeat. This preserves ventilation without compromising exclusion.

Design Features That Help Long-Term

Build in an Inspection Hatch

One of the most useful and most frequently overlooked design features is a liftable board or access hatch positioned to allow inspection of the under-deck void. TDCA guidance specifically recommends this, particularly near manholes or drain covers where rats are more likely to be active. By the time most homeowners hear rats beneath their deck, the problem is already well established. Building in easy access from day one — without having to lift random boards and risk damaging fixings — is a low-cost design decision with an outsized practical benefit.

Keep the Space Under the Deck Unattractive

Physical exclusion works best when the space beneath the deck is also made as unattractive as possible for nesting. Lay weed-control fabric beneath the deck, topped with gravel or chippings — this reduces available nesting material and makes the sub-deck area much less hospitable. Maintain a vegetation-free perimeter by clearing grass and ground cover back from the deck edge to create an open zone that makes rat movement more exposed. Remove leaf litter and debris from beneath the deck periodically. A dark, debris-filled void is far more attractive to rats than a clean, open, well-drained one. Maintain a vegetation-free perimeter by clearing grass and ground cover back from the deck edge to create an open zone that exposes rat movement.

What If Rats Are Already Present?

If you suspect rats are already nesting under your decking, the sequence matters. First, do not seal access points. Closing gaps with active rats inside creates a more complex and damaging problem. Second, contact a qualified pest controller. A professional can identify the species, assess the scale of activity, locate burrow entrances, and put a targeted control plan in place. Third, once the infestation has been dealt with, install your exclusion barrier correctly and make the environmental changes described in this guide to prevent reinfestation. Trying to shortcut this sequence by simply blocking holes is one of the most common mistakes homeowners make — and one of the most likely reasons rat problems reappear.

How Composite Decking Reduces the Risk

There is one area where the choice of decking material makes a genuine practical difference: the sub-deck structure. Traditional timber subframes can splinter, rot, and provide easy footholds for gnawing — over time they can even become a source of nesting material in themselves. Aluminium or composite subframe systems, increasingly standard with premium composite decking installations, offer significantly less natural harborage and are far more resistant to gnawing damage.

At Duralive Decking, we regularly install composite decking systems from Millboard, Trex and NewTechWood across Merseyside, Cheshire, Liverpool, Warrington, St Helens, Widnes, Wirral, Wigan, Ormskirk and Formby. Our design approach always considers the sub-deck environment — including ground clearances, drainage, and where required, the integration of rat exclusion mesh as part of the build specification. If you're planning new composite decking, this is the ideal time to address rat prevention properly: before the boards go down, not after.

How to Stop Rats From Getting Under Decking: Final Thoughts

Rats under decking is a solvable problem — but only if the solution is properly specified and correctly installed. The right mesh, the right depth, the right installation method, and a deck design that supports long-term ventilation. Get those four things right and you'll have a structure that's genuinely inhospitable to rodents for the lifetime of the deck.

Thinking About New Decking or Rat-Proofing an Existing Deck?

Whether you're planning a brand-new composite deck or looking to properly rat-proof an existing structure, getting the details right at the design stage makes everything easier — and more effective in the long run.

At Duralive Decking, our free design service covers everything from deck layout and subframe design to ground clearances, drainage, and exclusion measures. We design decks that are built to perform — not just look great on the day they're finished. Our approach ensures:

• Correct sub-deck clearances and ventilation, in line with composite decking manufacturer requirements

• Integrated rat exclusion design where required, using the correct mesh specification and installation method

• A clean, low-maintenance sub-deck environment that is inhospitable to pests from the outset

• Premium composite boards and subframes from Millboard, Trex and NewTechWood, installed to manufacturer specification for maximum longevity

We don't just build decks — we design and construct outdoor structures that perform as well as they look, year after year. The result is a deck you can enjoy with complete confidence, knowing it's been built properly from the ground up.

👉 If you're considering new composite decking or want to rat-proof an existing deck anywhere across Merseyside, Cheshire, Liverpool, Warrington, St Helens, Widnes, Wirral or the wider North West, get in touch with Duralive Decking to arrange a site visit and free design consultation.