Keeping rats and mice out of a gear shed (and out of your crash pads)

A crash pad is a rodent's dream. It is soft, warm, dark inside, and usually stored somewhere quiet that people only visit at the weekend. Add a forgotten muesli bar in a pad pocket, a chalk bag with a few crumbs in the bottom, and a shed door that doesn't quite close, and you have a ready-made nest. Unfold a pad that has sat untouched all winter and you may find the foam chewed into a hollow.

This note is about keeping rats and mice out of the shed, garage or lean-to where you store climbing gear. It is practical rather than technical. For larger infestations, or anything involving the house itself, get proper advice.

Why rats matter in New Zealand

Rodents in a shed are a nuisance anywhere, but in New Zealand they are also part of a much bigger problem. According to the Department of Conservation's page on animal pests and threats, New Zealand's native wildlife evolved for a very long time without land mammals, which left it poorly equipped to cope with introduced predators.

All three rat species found here were introduced. DOC's rats page describes the ship rat as the most common, and a skilled climber that can reach bird nests high in trees. Rats eat birds, eggs, chicks, lizards, snails, weta and other insects, as well as seeds, fruit and flowers, and they compete with native wildlife for food. DOC links ongoing predator control to the Predator Free 2050 goal.

A well-sealed shed is a tiny thing in that picture, but every rat that doesn't find a warm, food-rich home in your backyard is one less in the neighbourhood.

Close the gaps

The best defence is not letting them in at all. Rats and mice can squeeze through gaps far smaller than you would expect, and they will gnaw to make a small gap bigger. Walk around the shed, inside and out, with a torch and look for daylight.

Common entry points include the gap under the door, the join between the walls and the floor slab or bearers, holes where pipes or cables come through, gaps around roofing iron and at the eaves, and vents with missing or rusted covers. Old timber sheds often have corners where boards have shrunk or rotted.

A door sweep or brush strip along the bottom of the door is one of the simplest fixes. Fine metal mesh is good for vents and larger openings, as rodents can chew through plastic and foam fillers. Where a gap needs filling, a tough filler that rodents can't easily chew is better than soft foam on its own. Keep the door shut, even on a quick visit, and fix any latch that lets it drift open.

Outside, cut back long grass and plants touching the walls, keep firewood and junk piles away from the shed, and don't leave pet food or compost scraps nearby. All of these give rodents cover and food right next to your gear.

Food and chalk-bag hygiene

Most climbers' sheds have more food in them than their owners realise. Before you store anything, go through it properly.

• Empty pad pockets, packs and approach bags of snacks, wrappers and fruit.
• Turn chalk bags inside out and shake out crumbs; a little food mixed with chalk is enough to draw interest.
• Store any food you do keep in the shed in sealed metal or hard plastic containers.
• Hang chalk bags, ropes and slings off the floor rather than leaving them in a heap.
• Wash tape, finger tape scraps and sweaty clothing out of bags before storing them.

Pads themselves are best stored standing on edge or folded, off the floor if possible, with zips closed. That makes them harder to get into and easier to check.

Signs you already have visitors

Rodents are good at staying out of sight, so look for what they leave behind. Droppings are the clearest sign, often near walls or in corners. Gnaw marks on timber, plastic and pad fabric are another. You may find shredded paper, foam or fabric gathered into a nest, smudge marks along regular runs, or a musty smell. Scratching or scuttling at night is a giveaway.

If you find a chewed crash pad, check the foam carefully. A small hole in the shell can hide a large hollow inside, and contaminated foam is unpleasant to handle and to land on. Wear gloves, avoid stirring up dust from droppings, and clean the area thoroughly. A pad with badly chewed or soiled foam may need its foam replaced, and if the damage is extensive it is safer to retire it than to trust it on a hard landing. Our note on crash pads and spotting covers what a good pad should do.

If they're already in

Once you have sealed the gaps and removed the food, any rodents still inside need to be dealt with. Traps are the usual choice in a gear shed; place them along walls where rodents run, and well away from where children or pets can reach. Be wary of using poison bait in a shed full of gear: rodents can die inside walls or deep in a pad, and baits can harm other animals.

Check traps often, and keep checking for new signs for a few weeks afterwards. If activity carries on, or you find signs in the house too, get advice from your council or a rodent control service such as Pest Management Auckland.

A shed that is dry, sealed and free of food will also be kinder to everything else you store there, from timber offcuts for the next wall project to holds and skin-care kit. For more on building and looking after a wall at home, see our note on planning a home bouldering wall.