PIR insulation
Insulation between floors: what to check when footsteps are the problem
At a glance
Insulation between storeys may serve thermal and acoustic purposes, but these are not interchangeable criteria. If the aim is to reduce footstep noise, comparing PIR, EPS, XPS and mineral wool means examining a specific floor assembly rather than thermal conductivity alone. The supporting floor, proposed resilient layer, loads and junctions at walls and services all matter. This guide helps describe the problem and collect information for selecting a solution with a designer or acoustics specialist. It also explains why a test result for another assembly is not a promise of identical performance after renovation. It does not prescribe one board or thickness for every floor.
Describe the noise and the rooms
Start by recording what is heard, where it is heard and which activity produces it.
Footsteps, a chair being moved and conversation do not describe the same problem. Note the source room and the room affected. Include the floor finish and any changes after previous renovations. This helps plan an investigation before another layer of boards is ordered.
Identify the existing construction
For a renovation, gather information about the structural floor, screed or subfloor and finish. Identify any concealed layers that remain unconfirmed. Do not assign performance to an existing floor from its visible finish or a single thickness measurement at a doorway.
Establish which side can be accessed for work. Replacing the floor above and working on the ceiling below involve different practical arrangements. In an occupied building, agree room access, furniture removal and the work sequence before comparing contractors’ offers.
Compare complete floor solutions
The resilient layer in a floating floor has a defined role within the assembly. An arbitrary board of similar thickness is not an equivalent replacement. Alongside acoustic data, confirm suitability under the proposed loading and compatibility with the remaining layers.
Keep the tested assembly description with its result. Check the base, layer types and thicknesses, and the conditions covered. List differences between the documented solution and the planned renovation for assessment rather than quoting a decibel figure on its own.
Inspect junctions as well as the main area
Mark the room perimeter, pipe penetrations and other floor connections on the plan. These details matter because a rigid connection can bypass the resilient layer. Their construction should follow the chosen solution rather than improvised installation accessories.
Check the junction with the corridor and neighbouring rooms too. Work within the middle of one room cannot be assumed to address every sound transmission path. If the cause remains unclear, agree the required investigation or measurements before finalising the work estimate.
Agree the work and inspection scope
Specify the complete solution and the locations to be checked before concealment. Agree who will inspect the resilient layer and its terminations. Photographs labelled by room help later enquiries, but do not replace the required workmanship assessment.
Submit any proposed board substitution with data relevant to this assembly. Lower thermal conductivity or a similar price does not establish acoustic equivalence. Identify the accepted version in the order so the delivered material matches the agreed solution.
Assess the outcome against the agreement
Agree how the outcome will be assessed before work starts. If measurements are planned, define their scope with a specialist. Occupant impressions are useful feedback, but should not be presented as laboratory results or verification of a property that has not been measured.
Retain the installed layer schedule, agreed changes and material documents. During a later floor replacement, these records help identify the components of the acoustic solution. They also support future renovation discussions without guessing what lies beneath the finish.
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