100mm Rockwool Flexi Acoustic Sound Insulation Slab (4.32m2/Pack)

URN: 3002218
£41.30ex. VAT £9.56 per m2
£41.30ex. VAT
£9.56 per m2
Bulk Discount
6+ packs 12+ packs 18+ packs
£40.47ex. VAT £40.06ex. VAT £39.24ex. VAT
Coverage required
m
m
Based on your total area of m2 (inc. 10% wastage) - of these are required (actual coverage of m2)

We recommend purchasing at least 10% extra product to allow for errors, damages or obstacles

Nationwide Delivery

Fri 17 Oct

Order by 2pm tomorrow
  • 19hrs
  • 57mins
  • 47secs

Delivery & Returns Info

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URN: 3002218
£41.30ex. VAT

Delivery & Returns Information

How Our Delivery Works

We work with a nationwide network of trusted suppliers. As a result, items in your basket may be supplied by different suppliers and delivered separately. Where this applies, you'll see multiple delivery charges at checkout. We always aim to group products from the same supplier to keep delivery costs as low as possible.

Delivery Areas & Charges

Delivery charges listed on our website apply to mainland UK, excluding the following postcode areas: AB, CF, DD, DG, FK, KW, IV, LA, LD, LL, NP, PA, PH, SA, SY
If your delivery address falls within one of these postcode areas, we’ll be in touch before processing your order to confirm any additional delivery costs.
Please note: We do not currently offer delivery outside the UK mainland.

Standard (Nationwide) Delivery

Insulation, Plasterboard and Drylining Products
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Over £350 ex. VAT FREE
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Express Delivery

Express Delivery - Insulation and Plasterboard & Drylining
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Under £400 £50 ex. VAT
Over £400 ex. VAT £35 ex. VAT
Express Delivery - Timber & Sheet, Building Materials, Joinery and Gardens & Landscaping Products
ORDER VALUE DELIVERY CHARGE
Under £300 £50 ex. VAT
Over £300 ex. VAT £35 ex. VAT

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Returns

We offer a 30 day returns policy on any faulty products.

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Key Features

  • {{home}} Use in ceilings, walls and floors
  • {{local_fire_department}} A1 non-combustible
  • {{volume_off}} Excellent acoustic and thermal performance
  • {{build}} 600mm width to fit between studwork

Technical Specification

Technical Specification
Product:Flexi
Material Type:Rock Mineral
Thickness:100mm
Width:600mm
Length:1200mm
Pieces Per Pack:6
Sales Unit:Pack
Sales Unit Coverage:4.32m2
Brand:Rockwool
Manufacturer's Reference:123326
Thermal Conductivity:0.038W/mK
Fire Rating:A1 Non-Combustible

Product Overview

Stone wool insulation slab, measuring 100mm in thickness and cut to 1200 × 600mm, for use in partitions and floors.

With a patented flexible edge, it securely friction fits within framed constructions, reducing the need for excessive cutting and limiting waste on site.

In a single solution, it provides reliable acoustic absorption, effective thermal insulation with a conductivity of 0.038 W/mK, and the highest level of fire safety (A1 non-combustible).

Its semi-rigid form allows straightforward handling and installation, while maintaining a close fit to minimise gaps that could compromise performance.

At 100mm thick, this slab offers a substantial increase in acoustic and thermal performance compared to slimmer profiles. 

Its greater depth enables higher levels of airborne sound reduction between rooms and floors, while also improving energy efficiency by reducing heat loss through the building envelope.

Features & Benefits

  • FLEXI Edge® along one side: Ensures snug, continuous fit in timber or metal frames, reducing gaps and air leakage.
  • Non-combustible stone wool (Euroclass A1): Contributes to fire-safe wall, floor, and roof constructions.
  • Effective acoustic absorber: Reduces airborne sound transmission through stud partitions and intermediate floors.
  • Thermal conductivity 0.038 W/mK: Supports energy-efficient envelopes within framed build-ups.
  • Will not slump, even if studs shrink: Maintains full fill and consistent performance over time.
  • Easy to handle and cut: Speeds installation and fitting around services with minimal waste.
  • Slab size 1200 x 600mm: Standard board dimensions suit common stud spacings.
  • 100mm thickness: Delivers high levels of airborne sound reduction between rooms and floors, as well as improved thermal resistance for better energy efficiency.

Applications

  • Timber or metal stud partitions: Improves airborne sound reduction and thermal performance.
  • Party walls in timber frame: Used within twin-frame/independent stud solutions to address acoustic and thermal bypass.
  • Suspended timber floors: Laid between joists; supports sound control and U-value targets when used with appropriate membranes.
  • Pitched roofs and warm/hybrid frames: Between rafters or as part of hybrid build-ups to enhance thermal continuity.

Installation Guidance

  • Friction-fit installation: Flexible edge holds slabs tightly in place, reducing the need for mechanical fixings.
  • Cut to fit with a sharp knife: Ensures minimal waste and precise fitting around services.
  • Avoid gaps or voids: Maintains full thermal, acoustic, and fire resistance performance.

Compliance & Performance

  • Reaction to fire classification A1 (EN13501-1): Fully non-combustible for high fire safety.
  • Thermal conductivity 0.038 W/mK: Provides consistent insulation in framed constructions.
  • High acoustic absorption: Tested to provide broadband sound reduction in lightweight partitions.



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