Animals Under Shed
Garden sheds attract a wider range of animals than most homeowners realise. Rats and mice are the most common — and the most damaging — but foxes, hedgehogs, cats, and a range of other garden wildlife also use shed sub-bases as shelter and nesting sites. Understanding which animals are present determines the appropriate response.
Which animals use shed sub-bases and why
The sub-base void beneath a garden shed is structurally similar to a natural earth burrow or cavity. It is dark, dry, thermally stable, and sheltered from weather and predators. These conditions attract a wide range of species that share the same basic harbourage needs — regardless of whether they are categorised as pests or wildlife.
Rats and mice are the most frequently reported species. They exploit shed sub-bases year-round, with activity peaks in autumn when natural food sources diminish. Foxes use shed sub-bases as breeding dens, particularly in urban and suburban gardens where alternative den sites are limited. Cats — both domestic and feral — use shed sub-bases for shelter in cold weather and as birthing sites in spring. Hedgehogs, increasingly rare but still present in many gardens, use shed sub-bases for hibernation.
The appropriate response to each species is different. Rodents are controlled under pest management legislation. Hedgehogs and some other wildlife species have different legal protections. But the structural solution — a physical barrier that prevents access — is the same across all species.
Signs of animal activity under a shed
Identifying which animal is present beneath a shed requires attention to several indicators. Rat activity typically presents as excavated soil at the perimeter, slab-lifting in extreme cases, and distinctive cylinder-shaped droppings. Mouse activity is more discreet — small droppings, gnaw marks on low timber surfaces, and occasional scratching sounds. Fox presence announces itself through persistent, distinctive odour, and often through the sight of the animal entering or leaving the sub-base.
Cat activity is similar to fox in terms of the sheltered access pattern but without the strong odour. Hedgehog signs include leaf and grass nesting material at the perimeter and a characteristic shuffling sound. Any of these signs warrants investigation and, for rodent species, prompt action.
Addressing the structural cause, not just the symptom
Pest control visits, deterrents, and one-time trapping address the current occupants but not the access route. Sheds that have had one rodent infestation, treated and resolved, will almost always have a second — because the access point that allowed the first infestation remains open.
The structural cause is straightforward: a gap between the shed base and the ground. That gap may be at the junction of the bearer frame and the paving surface, at a corner where the frame has lifted slightly, or at a service penetration. Any of these is sufficient for mouse entry. The permanent solution is a barrier that closes the gap at ground level, not at the perimeter surface.
Permanent exclusion: full-footprint ground barrier
A welded wire mesh barrier installed flat at ground level beneath the full footprint of the shed — before the shed is positioned — is the most effective multi-species exclusion approach. The mesh prevents burrowing entry from any direction and provides a physical barrier that is impervious to the gnawing capability of both rats and mice.
For sheds already installed, a perimeter barrier — mesh dug in to 150–200mm depth and folded flat beneath the base frame — provides useful secondary protection for rodents and most other species. For fox exclusion, the dug-in perimeter must be deeper, with an outward horizontal fold of 300mm to prevent digging beneath the barrier edge.
Before installing any exclusion barrier around an existing shed, it is essential to confirm that no animals are inside. One-way exclusion devices, installed at all known access points and left in place for 48–72 hours, allow any occupants to leave before the barrier is sealed.
The right product for this application
BaseShield™ SubBase Defence provides a permanent multi-species barrier for shed sub-base protection. Installed before the shed is positioned, it covers the full footprint and prevents burrowing access by rodents and other garden animals.
BaseShield™ SubBase Defence
Forti NovaA purpose-built rolled sub-base barrier system designed specifically to prevent rodent access beneath raised structures. Supplied in 1m × 25m rolls — covering 25m² per roll — with a 7.66mm clear mesh opening and hot-dip galvanised finish applied after welding.
Roll size
1m × 25m
Coverage
25m² per roll
Mesh opening
7.66mm
Construction
Welded wire
Finish
Hot-dip galvanised
Wire diameter
0.80mm
Installation
For new shed installations, deploy BaseShield before the shed is positioned. For existing structures, a perimeter installation — mesh dug in at least 150mm and folded flat — provides secondary protection, though complete footprint coverage cannot be achieved without lifting the structure.
Read the full installation guideFrequently Asked Questions
Stop access beneath your structure
BaseShield™ SubBase Defence is installed during construction to provide permanent sub-base protection. Designed for garden rooms, modular buildings, decking and screw pile foundations.