Raised Structure Protection: Rodent Barriers for All Building Types

Raised structure protection refers to the measures taken to prevent unwanted access beneath the floor of any building or surface that sits above ground level. The structures this applies to are varied — garden rooms, modular offices, composite decking, timber decking, garden sheds, screw pile buildings, and any other raised floor construction with a void between the underside of the floor and the ground beneath it.

The common thread is the sub-base void. Whenever a floor is elevated above ground level, that void exists. And wherever that void exists without a physical barrier, it is accessible — to rodents, wildlife, moisture, and debris.

Raised structure protection at the sub-base level is a construction consideration, not a reactive one. It is most effectively addressed during the build process, at the foundation preparation stage, before the floor frame is set. At that point, access is straightforward, coverage is complete, and the cost is minimal relative to the cost of remediation after access is established.

Garden rooms and garden offices: Raised on bearer frames, screw piles or adjustable feet. The sub-base void is enclosed but open at the perimeter. See our specific guide to rodents under garden rooms.

Modular and off-site buildings: Delivered as complete structures to a prepared foundation. Sub-base access must be closed before the module is placed. See rodent barriers for modular buildings.

Raised composite and timber decking: Creates a horizontal shaded void. Rats are the most common species. See rats under decking and animals under decking.

Garden sheds and outbuildings: Mice are the most common species. Even minimal ground clearance is sufficient for access. See mice under sheds and stopping animals under sheds.

Screw pile and ground screw foundations: No perimeter base — the full sub-base is open from all angles. See ground screw rodent protection.

Sub-base protection for raised structures is not a standard specification item in the construction of domestic garden buildings. Building regulations for structures of this type in the UK do not require it. Most garden room and decking contractors do not include it in their standard scope of works. The issue is invisible once construction is complete, and it does not announce itself for weeks or months after the build.

The result is that sub-base rodent access is treated as a maintenance or pest control problem, rather than a construction omission. This is a mistake. The correct approach is to specify and install protection at the build stage — at negligible additional cost — rather than to remediate a well-established rodent problem after the fact.

For a detailed explanation of why the problem is so commonly missed, see our complete guide to preventing rodent access beneath raised structures.

BaseShield™ SubBase Defence is a rolled welded wire mesh sub-base barrier system designed specifically for installation beneath raised structures. Specification: 7.66mm clear mesh opening, 0.80mm wire diameter, hot-dip galvanised after welding. Roll size: 1m × 25m (25m² per roll).

It is designed to be installed during the foundation preparation stage of a new build — before the floor frame is set — and is compatible with all common foundation types used in domestic raised garden structures.

BaseShield is a construction component. It is specified at the design stage, supplied as part of the build programme, and installed before the floor is built above it. No maintenance is required after installation. The product is designed to last the lifetime of the structure.