7 Best Filter Cellar Drain Covers For Predator Protection DIY

That telltale scratching sound from the cellar isn’t just a nuisance; it’s a direct threat to your winter stores. A determined rat or weasel can turn a well-stocked root cellar into a contaminated mess overnight. The most common entry point isn’t a cracked foundation or a loose door, but the often-overlooked exterior drain.

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Securing Your Cellar: DIY Predator-Proof Drains

An open cellar drain is an engraved invitation for predators and pests. It’s a direct, underground highway leading straight to your potatoes, apples, and canned goods. Standard plastic grates are designed to stop leaves, not the powerful jaws and claws of a raccoon or the wriggling body of a snake.

The goal isn’t just to cover the hole, but to create a barrier that is both permeable to water and impermeable to wildlife. This means thinking about material strength, opening size, and secure fastening. A loose cover is just a fun puzzle for a raccoon, and a flimsy one is a minor inconvenience for a determined rat.

Before you choose a material, assess your specific threat. Are you dealing with mice and voles, or larger problems like skunks and raccoons? The smaller the pest, the smaller the mesh or opening you’ll need. The bigger the predator, the more critical raw strength and secure anchoring become. This isn’t a one-size-fits-all problem; your solution must match your local pest pressure.

Yardgard Hardware Cloth: A Versatile DIY Solution

Hardware cloth is the go-to starting point for many DIY farm projects, and for good reason. It’s inexpensive, widely available at any hardware or farm supply store, and easy to work with. You can cut it to size with a simple pair of tin snips and bend it by hand to fit irregular shapes.

For a cellar drain, a piece of 1/4-inch or 1/2-inch galvanized hardware cloth can be cut to fit just inside the drainpipe or shaped into a cap that sits over the opening. Secure it with construction adhesive or a few concrete screws with large washers. This creates an immediate and effective barrier against leaves, snakes, and larger rodents.

However, it’s crucial to understand its limitations. Hardware cloth is a deterrent, not an impenetrable fortress. A truly motivated rat or squirrel can and will chew through the thin galvanized wire over time. It’s an excellent, low-cost solution for low-pressure situations or as a primary filter layered with a stronger material on top.

Expanded Steel Sheet for Maximum Rodent Protection

When you graduate from rodent deterrence to rodent prevention, you need to upgrade from woven wire to solid metal. Expanded steel is made by slitting a solid sheet of steel and stretching it, creating diamond-shaped holes without any welds or weaves to break. This makes it incredibly strong and resistant to chewing.

This is the material you use when you know you have a persistent rat problem. A small sheet from a metal supplier can be cut with an angle grinder to fit perfectly over your drain opening. Because it’s so rigid, you can anchor it directly to the surrounding concrete with tap-cons, creating a truly immovable barrier.

The main tradeoff is rust. Unless you buy galvanized or stainless expanded steel (which costs more), a bare steel sheet will rust quickly. A simple solution is to clean it thoroughly with a wire brush and apply a few thick coats of a rust-inhibiting metal paint. This small bit of prep work ensures your rodent-proof barrier lasts for years.

Grainger Perforated Aluminum for a Clean Finish

If your cellar drain is in a visible area, like next to a patio or walkway, aesthetics might matter as much as function. Perforated aluminum sheet offers a clean, professional look that hardware cloth or raw steel can’t match. The holes are perfectly uniform, and the aluminum itself provides a bright, rust-proof finish that will never stain your concrete.

This material is a good middle-ground solution. It’s significantly stronger than hardware cloth and completely impervious to rust, unlike untreated steel. While a large, powerful animal could potentially deform a thin sheet, it’s more than tough enough to stop any common rodent from chewing through.

The primary considerations are cost and availability. You’ll likely need to order it from an industrial supplier like Grainger or a specialty metal shop, and it costs more than steel. But if you want a "do it once, do it right" solution that also looks good, perforated aluminum is a fantastic choice.

NDS Pro Series Grate: A Heavy-Duty Intruder Block

Sometimes, the best DIY solution is knowing when not to DIY. For standard-sized drains (like 3-inch or 4-inch round pipes), a purpose-built product like an NDS Pro Series atrium grate can be the fastest and most effective option. These are made from thick, UV-resistant structural foam polypropylene and are designed to be driven over.

While plastic might sound weak, the sheer thickness and design of these grates make them incredibly tough. The openings are small enough to block mice and voles, and no raccoon is breaking the dome-shaped structure. Installation is as simple as pushing it into the pipe; the friction-fit tabs hold it securely in place.

The only real downside is the lack of customizability. If you have an odd-sized or square drain, this won’t work. But for common round drains, it provides an instant, heavy-duty, and surprisingly effective predator block with zero cutting or fastening required. It’s the perfect solution when your time is more limited than your budget.

304 Stainless Woven Mesh for Ultimate Durability

For the absolute toughest, longest-lasting solution, nothing beats a heavy-gauge stainless steel woven mesh. This is the material used in industrial filters and security screens. It combines the small opening size of hardware cloth with the incredible strength and corrosion resistance of stainless steel.

A piece of 1/8-inch or 1/4-inch mesh made from 304 stainless steel will stop everything from mice to raccoons and will never, ever rust. It is the definitive permanent solution. You can fasten it down over the drain and forget about it for the rest of your life.

This performance comes at a high price. Stainless mesh is the most expensive option on this list and is also the most difficult to work with. You’ll need an angle grinder with a cut-off wheel to get through it, and the cut edges are exceptionally sharp. This is overkill for most situations, but if you’re battling persistent pests and corrosive soil conditions, it’s the only material that is truly guaranteed to win.

Repurposed Cast Iron Grill Grate: A Tough Build

Before you throw out that old charcoal grill, take a look at the cooking grate. Old cast iron grates are incredibly heavy, durable, and often the perfect size to cover a common cellar drain or window well. Nothing is chewing through solid cast iron.

This is the ultimate scavenger’s solution. With a bit of luck, you can find a grate that fits your opening with little to no modification. Its sheer weight is often enough to keep it in place, preventing all but the most determined raccoons from lifting it.

The challenge is the condition. An old grate will be rusty and caked with grime. A good session with a wire wheel on an angle grinder, followed by a coat of high-heat, rust-proof paint (like the kind used for wood stoves) will bring it back to life. It’s a bit of work, but it provides an unbeatable level of security for practically no cost.

Trex Decking Scraps: The Rot-Proof DIY Cover

Metal isn’t your only option. If you have scraps of composite decking like Trex left over from a project, you have the makings of an excellent drain cover. Composite decking is designed to be impervious to rot, moisture, and insects, making it a perfect material for ground-contact applications.

Using standard woodworking tools, you can cut a piece of decking to the exact size and shape of your drain. Then, using a drill press or a hand drill, you can bore a series of 1/2-inch or 3/4-inch holes to allow for water drainage. The material is dense and heavy, so it stays in place well.

While a highly motivated rat could eventually chew through it, composite material is not a preferred food source and is far more difficult to gnaw than wood or soft plastic. This is a fantastic use for a material that might otherwise go to waste. It’s a low-cost, long-lasting solution that leverages resources you may already have on hand.

Securing your cellar drain isn’t a complicated project, but it requires choosing the right material for your specific pressure and budget. By moving beyond flimsy plastic covers and implementing one of these durable DIY solutions, you can close a critical entry point for good. A secure cellar means your hard-earned harvest stays safe, sound, and yours.