How to Build a Feral Cat House for Winter | Insulated Tote Shelter

For the full breakdown, see our best Feral Cat House For Winter guide.

When temperatures drop, community cats need a dry place out of the wind, and the most reliable shelter you can build in an afternoon starts with a plastic storage bin. The design is simple: cut a small doorway, insulate the walls with rigid foam, fill the floor with straw, and seal it against the weather. If you would rather buy a ready-made option than build one, see our tested roundup of the best feral cat houses for winter before you shop.

The Basic Design: What Makes A Shelter Work

A good outdoor shelter does three things: it blocks wind, sheds moisture, and traps body heat. The standard DIY build is a 20-gallon plastic tote with a Styrofoam lining and a straw floor. The plastic shell stops rain and snow, the foam adds insulation, and the straw gives cats a dry nesting material that does not hold water against their fur.

Alley Cat Allies, a leading feral-cat welfare group, recommends shelters at least 2 to 3 feet long and 18 inches high. The doorway should be roughly 6 inches by 6 inches—small enough to keep heat in and discourage larger animals, but big enough for a cat to enter comfortably. Cut it near a corner, several inches above the floor, so rain and snowmelt stay outside.

Step-by-Step: Building The Tote Shelter

Here is the assembly order used in the most widely published shelter plans:

1. Cut the doorway. Trace a 6-inch square on one side of the tote, near a corner and a few inches up from the bottom. Warm the plastic with a hair dryer before cutting to reduce cracking, then cut with a box cutter or hole saw.
2. Line the interior with foam. Cut rigid Styrofoam or similar foam board to fit the floor and walls. The Ontario SPCA’s plan calls for ¾-inch foam sheets. Leave a small gap below the lid rim so the roof panel can sit flush.
3. Cut matching holes. Trace the doorway shape onto the foam lining and cut it out so the opening stays clear.
4. Fill the floor with straw. Pack several inches of straw across the bottom. This is the only bedding that works—straw sheds moisture, while blankets and towels soak it up and freeze.
5. Add the roof panel. Place a foam panel across the top of the insulation, then close the outer lid tightly.
6. Seal and secure. Tape the lid seam with strong duct tape or Gorilla tape, drill a few small drainage holes in the bottom corners, and weigh the shelter down with bricks or pavers so it survives wind.

When you are done, the shelter should feel solid, have no visible gaps, and keep the straw completely dry inside.

Better Builds: Tote-In-Tote And Entrance Tunnels

Two upgrades make the basic design noticeably warmer. The first is the tote-in-tote method. Use a large outer tote and a smaller inner tote, cut matching entrances in both, then pack the gap between the two bins with straw before closing both lids. This double-wall design traps a thicker layer of insulation around the whole shelter.

The second upgrade is an entrance tunnel. Some groups, including the Ontario SPCA, fit a 6-inch piece of black tubing or a trimmed plastic flowerpot into the doorway. The tunnel blocks wind and rain from blowing straight into the sleeping area, and it gives cats a protected spot to sit just inside the entrance.

Whichever build you choose, avoid totes with flimsy flip-top or split lids—they admit cold air and moisture. Solid-fitting lids seal far better. And when cutting plastic, work slowly and keep your hands clear of the blade; the material can crack or slip unpredictably.

Materials Matter: What To Use And What To Skip

The materials you choose decide whether the shelter actually keeps a cat warm. Straw is the only bedding that works. Hay, blankets, towels, and fabric all absorb moisture, which then freezes against a cat’s body or grows mold.

For insulation, rigid foam board is the standard choice. A single 4-foot by 8-foot sheet of ¾-inch foam is enough for several shelters. Reflective insulation also works well when wrapped around the inside of the tote. For sealing, use a strong tape like Gorilla tape rather than standard duct tape, which can peel off in cold weather.

Placement matters as much as construction. Set the shelter against a wall or fence, with the entrance facing away from prevailing winds. Elevate it slightly on pallets or bricks so water drains away underneath. Check it weekly through the season—replace damp straw, re-tape any loose seams, and clear snow from the entrance.

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