Rodent Barrier for Raised Structures
Any structure built above ground level creates a sub-base void. That void is the access route that rodents exploit beneath garden rooms, decking, sheds, modular buildings, and screw pile foundations. A correctly specified and installed rodent barrier closes that access point permanently, regardless of the structure type.
Why all raised structures share the same fundamental vulnerability
The specific construction details vary — screw piles for garden rooms, joist frames for decking, concrete pads for summer houses, bearer frames for sheds — but the core structural feature that creates the rodent risk is the same in every case: a horizontal floor or deck elevated above the ground on a support system, creating a cavity beneath.
That cavity has the same characteristics across all structure types: it is sheltered from above by the floor structure, it retains ground warmth, it is dark and undisturbed, and it is accessible from ground level at the perimeter or wherever the support system creates gaps in the base detail. The conditions that make it attractive to rodents are structural, not circumstantial — they exist in every raised structure by definition.
This is why the same product and the same installation approach — a full-footprint ground-level barrier — works across all structure types. The access point is the same, and the barrier addresses it in the same way.
Structure-specific considerations
Garden rooms and garden offices on screw piles: the most open sub-base configuration. No solid perimeter base. Barrier must be deployed around individual pile positions before the bearer frame is set. The rolled format is essential — rigid panels cannot be threaded around pile positions.
Composite and timber decking: long, rectangular footprints, typically installed over a joist frame on adjustable pedestal supports or bearer blocks. The 1m × 25m roll format covers most deck lengths in a single run with minimal joins. Barrier must be deployed before the joists are fixed.
Garden sheds and outbuildings: typically smaller footprints on paving or concrete pads. The bearer frame sits directly on the hard surface, creating a perimeter gap at the junction. A full-footprint barrier under the shed or a dug-in perimeter barrier depending on whether the shed is new or existing.
Modular and off-site buildings: delivered complete to a prepared foundation. The sub-base barrier must be in place before the module is craned or rolled into position. Once the building is sited, retrofit access is not possible.
The product specification that works across all applications
The specification is consistent across all raised structure types: welded wire mesh, clear mesh opening maximum 8mm, wire diameter minimum 0.80mm, hot-dip galvanised after welding. This is the minimum specification for reliable exclusion of all common UK rodent species in permanent ground contact.
The variable between structure types is the format and quantity of the barrier product, not the specification. A small shed requires a fraction of the material needed for a large modular building, but both need the same product.
Installation principles across all structure types
Regardless of structure type, the installation principles are the same: deploy the barrier flat at ground level before the structure is built, cover the full footprint without gaps, overlap joins by a minimum of 100mm, and fold the perimeter edge upward against the foundation or frame to eliminate the edge gap. Secure at the perimeter with appropriate fixings.
The timing is also consistent: the barrier must be in place before the floor frame or deck frame is positioned. After the floor structure is built, complete footprint coverage is not achievable.
The right product for this application
BaseShield™ SubBase Defence is designed for use across all raised structure types. The same product, the same specification, the same installation approach — whether the application is a garden room, a deck, a modular building, or a timber shed.
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
Identify the installation window in your build programme — after foundations and before floor frame. Deploy BaseShield at that stage, cover the full footprint, overlap joins, and fold perimeter edges. The floor frame is then built over the completed barrier.
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.