Description
Rockwool Frontrock Super 100 mm is the specification-grade thickness in our dual-density Super range — a Euroclass A1 stone wool board engineered for multi-occupancy buildings, mid-rise residential blocks, and taller facades, supplied 3 slabs per pack covering 1.8 m². At this thickness the slab earns its place where fire-safety requirements, thermal performance targets, and wind-load resistance all converge in the same specification.
What Rockwool Super 100 mm Does in a UK EWI System
Whole-wall U-value compliance with non-combustible A1 classification across the external wall is the outcome Rockwool Frontrock Super 100 mm is engineered to deliver on UK mid-rise and high-specification EWI projects, at λ 0.036 W/mK and R 2.78 m²K/W in a single 100 mm slab. It sits in the broader mineral wool insulation range as the specification-grade thickness in the dual-density Super series, supplied 3 slabs per pack covering 1.8 m². The dual-density construction is what separates this slab from a uniform mineral wool board: 150 kg/m³ hardened outer face for the render and mechanical loads, 80 kg/m³ inner layer to compensate for masonry irregularities behind.
Why Specifiers Choose Rockwool Super 100 mm for UK Walls
- A1 fire classification for relevant buildings: Stone wool will not ignite, sustain flame, or contribute fuel load — current Approved Document B guidance typically drives non-combustible specification in the external wall construction of mid-rise residential and multi-occupancy buildings.
- Dual-density mechanical resilience: The 150 kg/m³ outer face carries compressive stress of ≥ 20 kPa, handling sustained wind-load pressures on upper storeys and point-load impact on ground-floor zones without deforming the render substrate.
- Specification-grade thermal performance: At R 2.78 m²K/W in a single 100 mm layer, the slab contributes meaningfully to whole-wall U-value targets on mid-rise refurbishment and new-build alike, with a typical wall U-value of around 0.21 W/m²K on steel-frame construction.
- Substrate-compensating inner face: The 80 kg/m³ back layer moulds to masonry irregularities of up to 10 mm, achieving full adhesive contact on uneven brick or block without extensive preparatory rendering.
- Vapour-open across the system: With μ ≈ 1, the slab keeps the dew-point profile inside the insulation layer rather than at the wall interface, protecting solid-wall and period masonry from trapped moisture.
- Acoustic uplift on urban facades: Dense fibrous core delivers measurable airborne-sound attenuation on multi-occupancy buildings facing roads, railway lines, or communal areas.
- Recyclable mineral composition: Manufactured from naturally abundant volcanic basalt, supporting BREEAM and circular-economy criteria on regulated projects.
Thermal Specifications — λ, R-Value, Reaction to Fire
| Property | Value | Standard |
|---|---|---|
| Thermal conductivity (λD) | 0.036 W/mK | EN 12667 |
| R-value at 100 mm | 2.78 m²K/W | EN 13162 |
| Reaction to fire | Euroclass A1 | EN 13501-1 |
| Water vapour resistance factor (μ) | ≈ 1 | EN 12086 |
| Specific heat capacity | ≈ 1030 J/kgK | — |
On a steel-frame new-build wall with cement particle board sheathing, 100 mm of Frontrock Super typically achieves a wall U-value in the region of 0.21 W/m²K — a figure supporting compliance pathways under current Approved Document L guidance, subject to project-specific calculation.
Physical Specifications — Density, Strength, Dimensions
Physical numbers below set the handling reality on scaffold — the additional thickness compared with the 80 mm Super slab falls within the softer inner layer rather than the dense outer face, so pack weight stays close to its smaller sibling while R-value steps up.
| Property | Value |
|---|---|
| Thickness | 100 mm |
| Slab dimensions | 1000 × 600 mm |
| Density (inner / outer) | 80 / 150 kg/m³ (dual-density) |
| Compressive stress at 10% deformation (CS(10)) | ≥ 20 kPa |
| Tensile strength perpendicular to faces (TR) | ≥ 10 kPa |
| Slabs per pack | 3 |
| Pack coverage | 1.8 m² |
| Pack weight | ≈ 16.2 kg |
| Weight per m² | ≈ 9.0 kg |
Where Rockwool Super 100 mm Performs Best — Buildings & Wall Types
The 100 mm Super slab is the specification thickness for buildings where fire strategy, thermal target, and mechanical load all sit in the same brief — mid-rise residential, student accommodation, care facilities, and the new-build steel-frame construction where these typologies cluster.
- Multi-occupancy and mid-rise residential: Provides A1 non-combustible insulation in the external wall construction where current Approved Document B guidance drives the material-level specification on relevant buildings.
- Steel-frame new build with CPB sheathing: Typically achieves wall U-values around 0.21 W/m²K in a single 100 mm layer, supporting compliance pathways under current Building Regulations.
- Pre-1919 solid-wall deep retrofit: Combines fire safety, vapour openness, and substrate compensation for uneven Victorian and Edwardian masonry — see the Victorian solid-wall retrofit guide for whole-elevation detailing context.
- Coastal and high-exposure elevations: Dual-density structure handles wind-load pressures on upper storeys; combined with stainless-steel fixings, the slab is suited to maritime and exposed sites.
- Care, education, and public-sector facilities: Where occupant safety standards and fire-strategy requirements typically converge on A1 specification across the facade.
How Rockwool Super 100 mm Fits Into a Full EWI System
Build-up runs fully vapour-open from substrate to render finish. Bond each slab to prepared masonry with Roker U grey adhesive for mineral wool and EPS, a cementitious formulation specified for stone wool fibres and doubling as the reinforcement base coat. The hardened 150 kg/m³ face receives the adhesive and base coat — branded face outward toward the render — and mechanical fixings from the EWI fixing accessories range apply at a minimum of 8 per m² through 60–90 mm washer plates.
- Adhesive + base coat: Roker U grey (cementitious, vapour-permeable) — same product bonds the slab to the substrate and reinforces the base layer with embedded mesh.
- Reinforcement mesh: Alkali-resistant fibreglass mesh embedded fully in the wet base coat distributes mechanical loads and resists cracking across the slab face.
- Mechanical fixings: 60–90 mm disc washer plugs at 8 per m² baseline; stainless-steel pins for coastal, exposed, or high-rise positions where corrosion resistance matters over the building lifetime.
- Render finish: Silicone or silicate topcoats keep the system vapour-open from substrate through to surface, in line with the breathing-wall rationale for mineral wool.
How Rockwool Super 100 mm Compares to Sibling Slabs
| Specification | Super 80 mm | Super 100 mm (this product) | Super 120 mm | Super 160 mm |
|---|---|---|---|---|
| Range | Frontrock Super | Frontrock Super | Frontrock Super | Frontrock Super |
| Thickness | 80 mm | 100 mm | 120 mm | 160 mm |
| λ (W/mK) | 0.036 | 0.036 | 0.036 | 0.036 |
| R-value (m²K/W) | 2.22 | 2.78 | 3.33 | 4.44 |
| Density | 80/150 kg/m³ dual | 80/150 kg/m³ dual | 80/150 kg/m³ dual | 80/150 kg/m³ dual |
| Fire rating | A1 | A1 | A1 | A1 |
| Pack coverage | 1.8 m² (3 pcs) | 1.8 m² (3 pcs) | 1.8 m² (3 pcs) | 1.2 m² (2 pcs) |
| Typical use | Entry exposed/impact | Mid-rise, multi-occupancy | Deep retrofit U-values | Maximum performance |
For the full mineral-wool-versus-EPS decision walkthrough, our mineral wool vs polystyrene comparison sets out the trade-offs on cost, U-value per millimetre, and fire performance — relevant where the project fire strategy permits either material option.
How Rockwool Super 100 mm Performs in UK Weather — Moisture, Frost, Wind Loads
Wind-driven rain exposure increases with building height and aspect, placing sustained demands on both the moisture resilience and the mechanical integrity of the render substrate on upper storeys. Frontrock Super 100 mm answers both: the μ ≈ 1 vapour resistance lets walls dry outward through prolonged wet UK weather, while the 150 kg/m³ outer face resists wind-load pressures and differential movement that accumulate on taller elevations.
On solid-wall retrofits, the open-diffusion build-up keeps the dew-point profile inside the insulation rather than at the masonry interface — a long-term advantage where vapour-closed materials would risk trapping moisture against traditional brick. Combined with dimensional stability across the typical UK service range of −10 °C to +35 °C, the slab does not transfer thermal movement into the base coat or render at board junctions or reveal returns. The Building Safety Act 2026 facade-fire briefing sets out where this A1 classification becomes the specification driver on relevant buildings under current Approved Document B guidance.
Handling and Storage of Rockwool Super 100 mm on UK Sites
- Pack weight stays manageable: Super 100 mm packs weigh ≈ 16.2 kg — the same as the 80 mm variant — because additional thickness sits in the softer inner layer rather than the denser face.
- Cut clean with a long blade: Use a 150 mm or longer insulation knife with the branded face ("THIS SIDE UP") placed downward on a flat board, slicing through the softer back layer first to preserve the hardened outer face.
- Orient correctly: Branded face outward toward the render — reversing the slab places a compressible surface under the base coat, reducing adhesive bond and leaving fixing washers prone to over-driving.
- Stage deliveries on high-rise programmes: Smaller pack coverage (1.8 m²) means more packs per square metre of facade than Plus-range alternatives — match delivery to boarding progress to keep scaffold loading within calculated limits.
- Store dry: Opaque waterproof cover on site; saturated packs handle poorly overhead even though the hydrophobic treatment recovers thermal performance after drying.
Get these five right and the slab arrives at the wall in the same condition it left the pallet — particularly relevant on mid-rise programmes where stack density and handling tempo both rise.
Pro Tips From UK Installers Using Rockwool Super 100 mm
A few details separate the cleanest mid-rise installs from average — the points below come from EWI installers working on multi-occupancy and steel-frame projects across the UK.
- Confirm wind-load calculation before fixing density: 8 per m² is the baseline; mid-rise and coastal positions routinely move to 10–12 per m² following project-specific wind-load assessment, particularly above the third storey.
- Full-bed adhesive on the dense face: Apply Roker U as a full bed to the 150 kg/m³ face — dot-and-dab on a specification-grade slab undermines the load profile this product is designed to handle.
- Set fixings flush with the outer face: Drive washer plates so they sit flush with the hardened face, not recessed into the soft back — keeps the load on the high-density side where it belongs.
- Mesh-wrap reveal corners on every opening: Diagonal mesh patches reduce the most common crack location on rendered openings, particularly important on mid-rise where reveal counts run high per elevation.
- Stage deliveries to scaffold lift: The 1.8 m²-per-pack format means tighter delivery discipline than EPS — coordinate with scaffold loading calculations to avoid backed-up landings.
Certifications & Compliance — A1, EN 13162, REACH
- EN 13162: Factory-made mineral wool products for buildings — declared λ 0.036 W/mK, dimensional tolerances, and mechanical properties confirmed for the dual-density construction.
- EN 13501-1: Euroclass A1 reaction-to-fire — the highest reaction-to-fire classification, indicating non-combustible material with no contribution to fire at any stage.
- BS EN ISO 9001: Rockwool manufactures under certified quality management (BSI FM 02262), supporting batch-to-batch consistency across production runs.
- UK REACH compliant: No hazardous classifications associated with the stone wool composition; Rockwool fibres are not classified as possible human carcinogen.
Specifiers routinely cite these certificates as the baseline for non-combustible facade build-ups on relevant buildings — the material-level threshold the building designer needs before assembling a project-specific system specification.
Is Rockwool Super 100 mm Right for Your Project?
- Choose this slab if: Your project covers mid-rise residential, multi-occupancy, student or care facilities, or new-build steel-frame elevations where A1 fire safety, dual-density mechanical resilience, and a meaningful U-value contribution are all required at 100 mm thickness.
- Tighter space or budget? The Rockwool Super 80 mm slab shares the same 80/150 kg/m³ construction and A1 rating at R 2.22 m²K/W — suitable where slimmer profile or lower spend takes priority.
- Deeper retrofit U-value targets? The Rockwool Super 120 mm slab at R 3.33 m²K/W steps up the thermal performance for solid-wall deep-retrofit work targeting more ambitious U-value figures.
- Standard domestic project without high-rise specification? The Rockwool Plus 80 mm slab at 90 kg/m³ uniform density and λ 0.035 W/mK offers a slightly higher R-value per millimetre and larger pack coverage (3.0 m²) at a lower price for sheltered domestic facades.
- Low-rise where fire strategy permits combustible insulation? Browse the graphite EPS board range at λ 0.032 W/mK for higher thermal resistance per millimetre at reduced material cost.
All values stated are based on manufacturer-declared data from Rockwool and remain subject to confirmation through project-specific assessment. Specifications may be updated by the manufacturer without prior notice — verify against the current Declaration of Performance before specifying.
What to Order Next — Pack Sizes, Lead Times, Compatible Components
Each pack of Rockwool Super 100 mm covers 1.8 m² (3 slabs at 1000 × 600 mm). For full-system ordering, pair the slab quantity with a matched run of Roker U adhesive, the correct fixing length for substrate plus 100 mm slab depth, and a vapour-permeable render finish from the rendering range.
- Adhesive & base coat: Roker U grey adhesive 25 kg — calculate 4–5 kg/m² bonding plus 3–4 kg/m² for the reinforcement layer.
- Mechanical fixings: Select from the EWI fixing accessories collection matched to total embedment (substrate plus 100 mm slab depth) at a baseline 8 per m², adjusted upward for wind-load on mid-rise elevations.
- Lead time: Full-pack orders confirmed before the daily cut-off ship on the next UK working day.
FAQ — Rockwool Super 100 mm Coverage, Compatibility, Ordering
How many square metres does one pack of Rockwool Super 100 mm cover?
Each pack contains 3 slabs of 1000 × 600 mm and covers 1.8 m² laid flat. On mid-rise programmes, order with 5–10% allowance for cuts at reveals, returns, and parapet detailing, and plan deliveries against scaffold-loading capacity since smaller pack coverage means higher stack density per square metre than Plus-range alternatives.
What U-value does 100 mm Rockwool Super typically achieve?
On a steel-frame new-build wall with cement particle board sheathing, 100 mm of Frontrock Super typically achieves a wall U-value of approximately 0.21 W/m²K, based on Rockwool's published U-value tables. On a 215 mm dense block refurbishment substrate, a deeper slab is typically required to hit equivalent targets. The U-value calculation guide walks through the thickness selection method against current Approved Document L guidance.
How does Super 100 mm differ from Super 80 mm in practice?
Both share dual-density construction, A1 fire classification, and 1.8 m² pack coverage. The 100 mm steps R-value from 2.22 to 2.78 m²K/W, with the additional 20 mm sitting in the softer inner layer rather than the dense outer face — so the load behaviour at the render is unchanged while the thermal contribution improves. Choose 100 mm where the U-value target or the mid-rise specification context drives the additional thickness.
Does Rockwool Super 100 mm meet A1 requirements for relevant buildings?
The slab carries Euroclass A1 reaction-to-fire under EN 13501-1 — the highest classification, indicating non-combustible material. Where current Approved Document B guidance requires A1 or A2-s1,d0 insulation in the external wall construction of relevant buildings, this product meets the material-level threshold; the overall system specification remains a project-specific matter for the building designer.
What fixings are recommended for high-rise specification?
Use mechanical insulation fixings with 60–90 mm diameter washers at a baseline 8 per m² to spread load across the denser outer face. On mid-rise elevations, project-specific wind-load calculations typically raise this density to 10–12 per m², with stainless-steel pins recommended throughout for long-term corrosion resistance on exposed and coastal sites.
Will the dual-density slab work on uneven refurbishment masonry?
The 80 kg/m³ inner layer compresses against substrate irregularities of up to 10 mm, achieving full adhesive contact on uneven brick or block without shimming. For walls outside that range — typical on pre-1919 solid masonry — a levelling render coat applied before boarding brings the surface within the slab's compensation range.
Is this slab suitable for BREEAM and sustainable specification?
The slab is manufactured from naturally abundant volcanic basalt with no blowing agents carrying ozone-depleting or global-warming potential, and off-cuts can be returned to Rockwool's recycling programme. The A1 classification additionally contributes to fire-safety credits within sustainability assessment frameworks.
Technical Documentation — Rockwool Super 100 mm TDS & Datasheets