Rodent-Proof Expansion Joint with Compressible Core

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing expansion joints made of flexible materials like foam and epoxy resin are vulnerable to rodent damage, allowing entry into gaps between building structures, and the process of curing foam takes a long time to fill the cavity.

Innovation Solution

An expansion joint with an elongate core of resiliently deformable material and a flexible sheath of woven metal wire is used, which compresses to fit into the gap and expands to secure itself with friction, providing a rodent-proof barrier.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If flexible materials like foam and epoxy resin are used for expansion joints, then the expansion joint can accommodate structural changes, but rodents can easily gnaw through and enter the gap

Engineering Contradiction:
Improveaccommodation of structural changesVSAvoidrodent resistance
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The expansion joint combines a resiliently deformable core material with a flexible sheath made of rodent-resistant material. This composite structure provides both the flexibility needed to accommodate structural changes and the durability to resist rodent damage, resolving the contradiction between adaptability and reliability.

Inventive Principle:
Principle #40Composite materials

2Quantity of substance

If foam is used to fill the cavity, then the gap can be filled, but the curing process takes a relatively long amount of time

Engineering Contradiction:
Improvegap filling capabilityVSAvoidcuring time
Core Design Contradiction:
Quantity of substanceVSLoss of time

Solution Approach 1:

The invention extracts the filling function from the expansion joint itself, using the resiliently deformable core to provide the filling capability without requiring a separate curing process. The core is compressed for insertion and then expands to fill the gap, eliminating the time-consuming curing step while maintaining effective gap filling.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If the expansion joint is made rigid to prevent rodent entry, then rodent resistance improves, but the ability to accommodate expansion and contraction is reduced

Engineering Contradiction:
Improverodent resistanceVSAvoidaccommodation of structural changes
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention uses a flexible sheath made of rodent-resistant material that maintains its protective function while allowing the underlying resiliently deformable core to expand and contract. This flexible protective layer resolves the contradiction by providing rodent resistance without sacrificing adaptability.

Inventive Principle:
Principle #30Flexible shells and thin films

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The expansion joint effectively prevents rodent entry and damage while accommodating structural changes due to temperature and moisture, with quick installation and minimal preparation.

Implementation Method 1

the elongate portion of the elongate core compressible in a direction perpendicular to a line between the first and second ends of the elongate core, the expansion joint being compressed and inserted into the gap

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 2

the elongate core will compress in order to fit in the gap. The expansive force of the elongate core will then act to keep the expansion joint in place within the gap

Methodology Applied
Scientific EffectElastic Recovery: Elastic Recovery

Implementation Method 3

the expansion joint is held in place by friction between the surface of the flexible sheath and the surfaces of the first and second building structures

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4217549B1Expansion joint
Publication Date: 2026.01.28 RENTOKIL INITIAL 1927 PLC
  • EP4217549B1 patent drawingFigure 1a~1b
  • EP4217549B1 patent drawingFigure 2
  • EP4217549B1 patent drawingFigure 3

AI summary

An expansion joint for providing a rodent-proof barrier. The expansion joint comprises an elongate core formed of a resiliently deformable material, and a flexible sheath of a barrier material covering at least a part of the elongate portion of the elongate core. The elongate portion of the elongate core is compressible in a direction perpendicular to a line between the first and second ends of the elongate core, the elongate core being arranged to be compressed and inserted into a gap between first and second building structures, and to expand after insertion into the gap so that the expansion joint is held in place within the gap by friction between the surface of the flexible sheath and the surfaces of the first and second building structures.