Building components · Floor Build-Up
Perimeter Isolation Strip
Explains a small strip whose omission defeats an entire floor's acoustic isolation.
Educational reference entry. What this element has to do, and whether any particular arrangement of it is adequate, depends on the whole assembly, the loading, the exposure, local requirements, the manufacturer's instructions and qualified professional design.
Overview
What a isolation strip is
A floating floor layer that touches the walls around it is not floating. The perimeter isolation strip is the resilient material placed around the edge of the layer, keeping it clear of the walls at every point.
It is a small component with a disproportionate consequence. A floor perfectly isolated across its area but touching a wall at its edge has a direct path into the structure, and the whole isolation is compromised by that one line of contact.
Boundaries
How it differs from nearby elements
The distinctions that keep this entry from being a restatement of its neighbours.
- It is not the resilient layer beneath the floor. That handles the horizontal plane; the strip handles the vertical edge.
- It is not a movement joint. A movement joint accommodates dimensional change; this strip prevents acoustic contact, although both are discontinuities.
- It is not a skirting. A skirting covers the edge afterwards, and it is very commonly what bridges the strip.
Terminology
Common names and aliases
These names describe the same element. The library keeps one entry per component so that a trade term or a regional name never becomes a second, thinner page.
- edge strip
- perimeter strip
- edge isolation
Dependencies
What it depends on
What has to be right elsewhere for this element to do its job.
- Being continuous around the entire perimeter, including at doorways and behind fitted units.
- Extending to the full height of the floating layer, so contact cannot occur above it.
- Being trimmed rather than removed once the floor is complete.
- The skirting arrangement, since a skirting fixed to both wall and floor reconnects them.
Considerations
Topics that genuinely apply here
Subjects worth discussing about this element. These are discussion topics, never measured values, ratings or performance claims.
The perimeter is the shortest path from the floating layer into the structure, and it is the path most commonly left open.
The strip is installed early and trimmed at the end, and the trimming stage is where it is frequently cut back too far or removed.
It must be tall enough to cover the full depth of the floating layer, including any screed poured against it.
Materials
Commonly formed from
Material families this element is commonly realised in. This states common practice only — it is not a statement that any of these materials suits this component in a particular building, which depends on the whole assembly and on qualified review.
Assemblies
Building systems this element is met in
The role this component fills inside each assembly. A role describes what the element does there — it is not a statement that this component suits that system in any particular building.
Junctions
Interfaces this element takes part in
Junctions where the condition between this element and another governs how the construction behaves. These name the junction and the subjects it raises; they are not details, arrangements or approved ways of building.
Floating Layer to Perimeter
Where an isolated floor meets the walls around it, and where its isolation is most easily lost.
Raises: Acoustic continuity · Buildability · Movement
Where it is met
Application contexts
Building contexts where this element is commonly encountered. Association is not recommendation: appearing here does not mean the component suits every instance of that context, or any particular one.
- Building Interior
- Intermediate Floor
- Separating Construction
Clarifications
Commonly misunderstood
- That trimming the strip flush at the end is finishing. Cutting it below the top of the floating layer opens a contact path.
- That a skirting fixed to the floor is normal practice. Where a floor is isolated, a skirting fixed to both wall and floor bridges the isolation.
Conversations
Questions for qualified professionals
Questions worth asking someone with the project in front of them. This page cannot answer them.
- Is the isolation strip continuous around the whole perimeter, including doorways?
- Does it extend the full height of the floating layer?
- How will the skirting be fixed so that it does not bridge floor to wall?
- How is the strip protected from being cut back during finishing?
Go deeper
Related Build Design Hub guides
Planning guidance behind the decisions this element involves.
Preparation
Related planning checklists
Owner-side preparation before the conversation where this element comes up.
What this entry does not do
- No thickness, height, material or acoustic value is stated here.
- Acoustic isolation performance is tested rather than assumed; nothing here supports a claim about a result.
Floor Build-Up Elements
The deck, toppings, floating layers, isolation strips and voids that sit between a floor structure and its finish.
Browse all floor build-up entries →