How Long Does a Rodent Barrier Last in Ground Contact?
The durability of a sub-base rodent barrier is entirely specification-dependent. A correctly specified hot-dip galvanised welded wire mesh should last the lifetime of the structure above it — decades, with no maintenance required. An incorrectly specified product may fail within five years. Here is how to tell the difference.
What determines ground-contact durability
Sub-base barrier mesh is installed in permanent ground contact — beneath a structure, in direct contact with soil, subject to moisture, temperature cycling, and the organic acids produced by soil bacteria. These are aggressive conditions for any metal product. The specification that survives them long term has two key components: corrosion-resistant coating and a wire diameter sufficient to remain functional after partial coating degradation.
Corrosion protection is provided by the galvanising process — the application of a zinc coating to the steel wire. Zinc is a sacrificial anode: it corrodes preferentially, protecting the base steel until the zinc layer is consumed. The thickness of the zinc layer, and how it is applied, determines how long this protection lasts in ground contact.
Wire diameter matters because a thicker wire has more base metal to corrode through before failure. A 0.80mm wire, even in aggressive ground conditions, has significantly more reserve capacity than a 0.5mm wire. Thicker wire also provides greater initial resistance to gnawing.
Pre-galvanised vs hot-dip galvanised: the critical difference
There are two distinct galvanising processes used in wire mesh manufacture, and they produce products with very different lifespans in ground contact.
Pre-galvanising applies zinc to the wire before the mesh is welded. The zinc coating is present on the wire strands, but every weld point — where two wires are joined by electrical resistance welding — burns away the zinc coating and leaves bare metal. In ground contact, those bare weld points are the points where corrosion begins immediately. A pre-galvanised mesh in ground contact can show weld-point corrosion within two to three years.
Hot-dip galvanising is applied to the completed mesh after welding. The entire mesh — including every weld point — is submerged in molten zinc. The resulting coating covers all surfaces, including the weld joints. In permanent ground contact, a hot-dip galvanised welded wire mesh can achieve 25–50 years of service life under typical UK garden conditions, depending on soil pH and moisture levels.
What to expect from a correctly specified barrier
A hot-dip galvanised welded wire mesh barrier installed correctly as a sub-base barrier should be considered a permanent, passive component — like the damp proof membrane in a wall or the vapour barrier beneath a solid floor. It requires no maintenance, no inspection, and no replacement under normal conditions for the lifetime of the structure.
The product is designed to outlast the structure above it. In practice, the floor structure of a garden room, summer house, or deck may require replacement or major repair within 25–40 years. The sub-base barrier, correctly specified, should remain functional throughout that period.
What reduces barrier lifespan
Soil pH is the primary environmental variable that affects galvanised mesh lifespan. Highly acidic soils (pH below 5) accelerate zinc consumption. Most UK garden soils are in the pH 5.5–7.5 range, which is within the normal operating range for hot-dip galvanised steel. In highly acidic garden conditions — near conifers, in peat-heavy soils — additional corrosion protection may be warranted.
Incorrect installation reduces effective lifespan independently of material specification. A mesh product that is compressed, folded unevenly, or has damaged coating at cut edges will corrode faster at those points. Cutting the mesh with abrasive tools rather than tin snips creates heat-damaged edges that are more vulnerable to corrosion.
The right product for this application
BaseShield™ SubBase Defence is manufactured using hot-dip galvanising applied after welding, ensuring complete coverage of every weld point. It is designed as a permanent sub-base barrier for the lifetime of the structure above.
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
Cut BaseShield with tin snips rather than angle grinders to preserve the cut-edge integrity. Fold and secure at the perimeter before the structure is built over it. No subsequent maintenance of the barrier itself is required.
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.