Modular Building Protection Systems – Sub-Base Rodent Exclusion
Modular and off-site constructed buildings present a unique challenge for sub-base protection: the window for barrier installation is narrow. Once the module is craned or rolled into position on its foundation, access to the full footprint is no longer possible. Sub-base protection must be specified, supplied, and installed before the delivery date.
The modular building sub-base challenge
A modular or off-site building is manufactured as a complete unit — floor, walls, roof — and delivered to site as a finished or near-finished structure. The foundation system is prepared in advance, typically using screw piles or adjustable pad systems, and the module is positioned on the foundation in a single lift or roll operation.
This delivery process means the sub-base beneath the module is only accessible before positioning. Unlike a site-built structure, where the floor is constructed in stages and the sub-base can be addressed at multiple points in the programme, a modular building's sub-base is sealed from access the moment the module is set down.
Sub-base protection must therefore be specified as part of the foundation preparation programme — typically managed by the groundworks contractor or the foundation installer — before the module delivery date. It is not an afterthought; it must be a scheduled programme item.
Foundation types for modular buildings and their protection requirements
Screw pile foundations are the most common system for modular garden buildings. They are fast to install, require no concrete, and can accommodate level differences across the footprint. The sub-base above the pile grid is entirely open. The sub-base barrier is deployed over the pile grid — threaded around each pile position — before the module is delivered.
Adjustable pad systems are used where a more cost-effective alternative to screw piles is appropriate. The adjustable feet sit on a concrete pad or compacted surface. The sub-base barrier is deployed between and around the feet before the module is positioned.
Bearer frame systems — where a fabricated steel or timber frame is pre-installed on the pile heads to provide a ready surface for the module — are increasingly common. The sub-base barrier is installed before the bearer frame is assembled, or between the frame and the ground surface depending on the specific detail.
Programme coordination for sub-base protection
For modular building projects, the sub-base barrier installation sits within the groundworks programme, after foundation installation and before module delivery. Typical programme points:
Day 1–2: Pile or pad installation and levelling check. Day 3: Sub-base barrier deployment (BaseShield™) — approximately 1–2 hours for a standard modular building footprint. Day 4 onwards: Module delivery and positioning. The barrier is then permanently enclosed beneath the module.
Coordination between the groundworks contractor and the module supplier is essential to ensure the barrier is installed before the module delivery date. A last-minute barrier installation — attempted on the same day as module delivery — creates time pressure that leads to installation shortcuts.
What happens without a sub-base barrier in a modular building
A modular building without a sub-base barrier typically presents a rodent problem within one to three years of installation. Because the module cannot be lifted without significant cost and disruption, retrofit sub-base protection is not achievable. The only available responses are perimeter management — partial and ineffective — and ongoing pest control — reactive and indefinite.
The financial cost of reactive pest control over the lifetime of a modular building significantly exceeds the cost of sub-base barrier installation at the construction stage. For modular building manufacturers and suppliers, including sub-base protection in the standard specification protects both the product and the relationship with the end user.
The right product for this application
BaseShield™ SubBase Defence is specified as a foundation-stage component for modular and off-site buildings. It installs within the standard groundworks programme in 1–2 hours and is then permanently enclosed beneath the module — providing lifetime sub-base protection.
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 modular buildings, BaseShield must be installed before the module delivery date. Coordinate with the groundworks team to ensure the barrier is deployed, joined, and perimeter-secured on the day after the foundation installation is complete.
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.