Vivid Ready

Sanitation and hygiene

Pest-proof food and waste storage

Pest-proof food and waste storage: do this now

Exclusion, not control. A store with open access cannot be trapped clear, and rodents contaminate far more than they eat.

  1. Never sweep or vacuum dry droppings or nesting material. Damp it down first, wait a few minutes, wipe up wet and bag it. Gloves, and a mask if you have one.
  2. Torch round the outside at ground level and mark every gap over 6 mm.
  3. Pack gaps with steel wool, stainless or copper mesh, then lock it in with sealant. The metal stops them, the filler just holds it.
  4. Brush strips or metal kick plates on door bottoms. That gap is the commonest way in of all.
  5. Mesh air bricks and vents. Never block them solidly, ventilation still matters.
  6. Everything in the long store goes into metal bins, glass or clamp-lid buckets. Sacks and boxes are packaging, not storage.
  7. Raise it off the floor, off the walls, and split it across several places so one breach is not everything.
  8. Clear log piles, rubbish and dense growth back from the walls, and cover the compost.
  9. Inspect monthly for smears along skirtings and pipes. Grease marks show before anything else does.
Seal anything over
6 mm for mice, 13 mm for rats
Does not work
Foam, sealant, caulk, plastic, wood
New dry goods
Freeze 72 hours to kill insect eggs
Flies mean
Something uncovered, within metres

The mistake that costs lives: Expanding foam round a pipe entry. It sets hard, it looks exactly like a finished repair, and a rat chews through it in an evening. So does silicone, caulk, plastic and wood. The gap is only closed if there is metal in it: mesh or wire wool packed tight, with the foam holding the metal rather than doing the work. A building foamed shut is a building you have stopped checking.

Seal every gap over 6 mm and you exclude mice; over 13 mm and you exclude rats. Expanding foam and sealant do not work, because rodents chew straight through both.

Why this stops being cosmetic

In ordinary times a mouse in the kitchen is unpleasant. In a household holding months of food with no way to replace it, rodents are a direct competitor for the thing keeping you alive.

They do more damage than they eat. A rat contaminates far more grain with urine and droppings than it consumes, and a chewed sack spills the rest. Leptospirosis, salmonella and hantavirus are all rodent-associated, and rat urine in a water store is a genuine route to serious illness.

They also breed at a rate that outruns casual effort. A pair with unlimited food produces a colony within a season, so the aim is exclusion rather than control. Killing rodents in a building with a food supply and open access is bailing without plugging.

The gap sizes

They also climb, jump and swim. Rats climb brick, run cables and pipes, swim up drains, and gnaw a small hole into a large one. Assume any gap becomes a bigger gap given time.

Look for gaps where you do not normally look: under doors, around pipe and cable entries, air bricks, gaps at the eaves, behind kitchen units, where extensions meet the original wall, around the meter box, and vents. Take a torch outside at night and look at the building from the outside, low down, which is where they enter.

What actually stops them

Proofing the building

Work outside in, low first.

  1. Walk the perimeter with a torch, at ground level, and mark every gap over 6 mm.
  2. Doors: fit brush strips or metal kick plates. A gap under a door is the commonest entry of all.
  3. Pipe and cable entries: pack with mesh and seal.
  4. Air bricks and vents: cover with fine metal mesh. Never block.
  5. Eaves and roofline: mesh any gap. Rats climb well.
  6. Drains: keep covers intact and fitted. Rats come up drains.
  7. Around the meter box, waste pipe and overflow.
  8. Inside: behind and under kitchen units, around the boiler, under the bath.

Then remove the reasons to come:

  • Clear rubbish, log piles and dense vegetation away from the walls. Keep a clear strip so nothing has cover to work in unseen.
  • Move the wood pile off the wall, which the firewood page already recommends for other reasons.
  • Do not feed birds close to the building in a rodent problem.
  • Cover the compost heap, and keep cooked food and meat out of it.
  • Deal with the waste, per household waste with no collection.

Protecting the food store

Assume something will get in eventually, and make the store survive it.

  • Everything in the long-term store goes into a hard container. Sacks and boxes are packaging, not storage.
  • Metal dustbins are cheap, rodent-proof and hold a great deal. For grain, flour, pulses and pet food they are hard to beat.
  • Raise everything off the floor on pallets or shelving, and keep it away from walls, so you can see behind it and nothing has a covered run.
  • Inspect monthly. Droppings, gnaw marks, greasy smear marks along skirtings and pipes, shredded material, and a distinctive ammonia smell. Smears are the reliable early sign, because rodents follow the same routes and leave grease from their fur.
  • Store in several places rather than one. If something does get into a store, you lose part of the food rather than all of it. That is the same redundancy argument the playbook makes about caches.
  • Keep the store cold if you can. Cold slows insects as well as rodents.

Insects matter too. Weevils and moths arrive inside dried goods rather than walking in. Freezing new dry goods for 72 hours kills eggs and larvae before they go into store, which is worth doing routinely with flour, grain, rice and pulses while there is still a freezer. Bay leaves in the container are traditional and of modest effect.

Flies

Less dramatic than rodents and arguably more dangerous, because flies move directly between waste and food.

  • Cover everything, food and waste alike. A cover is the whole of fly control.
  • Fine mesh over windows in summer, and over any water store.
  • Deal with the source. Flies mean something is uncovered somewhere: the compost toilet, the heap, the bin, a dead animal. Find it.
  • Keep the compost toilet covered, per that page, since exposed material is what breeds them.
  • Fly papers and traps work as a supplement, never as the answer.
  • Maggots mean an uncovered protein source within a few metres. Find it rather than treating the maggots.

If they are already in

  • Exclusion first, always. Trapping in a building with open access is endless.
  • Snap traps work and are more reliable than most alternatives. Set them along walls, perpendicular, with the trigger toward the wall, since rodents run edges rather than open floor.
  • Bait with something sticky that cannot be removed cleanly: peanut butter, chocolate. Loose bait gets taken.
  • Set many traps at once, not one or two. A light effort teaches them to avoid traps.
  • Rodenticide is a poor choice in a household with children, pets and no vet, and poisoned rodents die in cavities and walls where they cannot be reached. In a long emergency, secondary poisoning of a cat, dog or owl that catches a poisoned rat is a real cost.
  • A cat is genuinely effective, and mostly as a deterrent rather than by killing.
  • Wear gloves handling carcasses, bag them, and wash thoroughly. See sharps and clinical waste for the disposal principles.

Why this matters: food

Last reviewed 2026-08-01

Checked against 3 sources
  1. Seal openings greater than about 6 mm (1/4 inch) to exclude mice, and greater than about 13 mm (1/2 inch) to exclude rats
  2. Rodents chew through wood, plastic, rubber, foam and common sealants; caulk and expanding foam are not reliable barriers
  3. Effective materials: steel wool or stainless and copper mesh packed tightly and locked in place, or sheet metal