When is slab insulation required?

Mineral wool slab insulation is installed to: Improve warmth in rooms above an unheated void or basement. Cut draughts rising through gaps in older floors. Reduce sound transfer between storeys. Boost heat retention in suspended timber floors. Comply with regulatory standards for insulation. Mineral wool is chosen here because it fills the cavity well, handles moisture safely, and adds acoustic improvement. Rigid boards cannot match these qualities in a timber floor setup.

How thick should slab insulation be?

Wool slab insulation is primarily used with suspended timber floors, not under concrete slabs. Thickness should be between 50mm and 150mm. It all depends on the thermal target and the depth of the joists. Upgrades and new builds working to achieve greater heat retention usually need 100–150mm.

How to cut slab insulation?

Insulation knives are ideal, but a fine-tooth handsaw or serrated bread knife is fine to use. Place the insulation on a flat surface. This ensures a neat and even cut. Mark the cutting line. Cut through the slab, keeping the edge straight. Remember to wear a long-sleeved garment, gloves, and a mask to shield the skin from loose fibres.

How to install slab insulation?

To install mineral wool slabs: Take note of the distance from stud to stud or joist to joist. Carefully cut the insulation so it is slightly wider than this distance by 10–15mm. This allows the slab to grip the sides firmly. Insert the wool slab gently into position so it friction-fits without any fixings. Cut and use smaller bits of the insulation to fill all gaps. Focus on the areas around pipes and corners. This will limit heat loss or sound leaks. Cover with flooring or plasterboard. Some applications may have extra steps or special requirements. So check the user manual to confirm what the process needs.

What is slab insulation?

Slab insulation is a name commonly used when referring to mineral wool insulants. These are semi-rigid sheets made from either rock wool or glass wool. What stands out about slab insulation is that it holds its shape pretty well and fits neatly between studs or joists. It is also breathable, fire-safe, and moisture-resistant, providing acoustic and fire protection in addition to general thermal insulation.

Where and how can insulation slabs be used?

Mineral wool slabs are used in a wide range of building projects because they are firm enough to hold their shape and flexible enough to fill awkward spaces. Here’s how they are used in the most common applications: Stud Walls Mineral wool slabs are a natural fit for stud partitions. Their semi-rigid structure lets them grip the sides of the studs, so they stay put without fixings. When installed in a compact, gap-free manner, they reduce noise between rooms and help retain warmth in the building. Because they are noncombustible, they also add an extra layer of fire protection inside the wall build-up. Suspended Flooring In suspended timber floors, mineral wool slabs sit between the joists. They push slightly against the sides to create a tight fit, stopping draughts that may rise from the void below. This helps rooms feel warmer and reduces sound movement between levels. The material also handles moisture safely – an important detail in older floors that need to breathe. Masonry Cavity Walls Mineral wool is used in cavity walls, but not the everyday slabs used for partitions. Instead, builders choose cavity-specific mineral wool boards designed to: resist water tracking across the fibres keep their shape over time fit neatly in brick-and-block cavities These boards slide into the cavity as the wall is built, creating a continuous layer of insulation from course to course. Rainscreen Facades Rainscreen systems use façade-grade mineral wool boards. These are firmer and denser than typical slabs and stay stable behind cladding while allowing moisture to escape through the ventilated cavity. Their noncombustible rating also supports fire-safe façade design. Installers fix these boards directly to the substrate before the ventilated cladding goes on. Soffits For soffits – like car park ceilings and exposed concrete decks – builders use high-density mineral wool boards made for overhead work. These boards often come with a protective facing so they can be left visible. They are fixed directly to the concrete slab, giving the exposed underside a neat finish while improving the thermal performance of the floor above.

Insulation Slab At Wholesale Prices

Insulation Slab Acoustic

Maintaining a cosy and energy-efficient environment in houses and buildings depends on insulation. Insulation slabs are among the most commonly used insulation products represented in different types on the market. They can be used in various applications while delivering great value to your projects. Insulation slabs help to regulate the temperature while reducing energy consumption and improving overall indoor comfort.

Read more about Insulation Slabs.

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Products in Insulation Slab

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Clear All Acoustic

50mm Rockwool RW5 Acoustic Insulation Slab 1200mm x 600mm 69.12m2 Pallet

50mm Rockwool RW5 Slabs can be applied to an array of general building applications for acoustic, thermal and fire protection of partition walls, ceilings, floors and roofs.

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60mm Rockwool Ablative Coated Batt 1200mm x 600mm x 0.72m2

60mm Rockwool Ablative Coated Batt is a mineral wool insulation product, pre-coated on both sides with a high performance ablative coating. Rockwool Ablative Coated Batt application includes multiple substrates including solid walls, floors, and flexible walls.

£27.20£32.64 Ex VATInc VAT
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60mm Rockwool Flexi Slab Acoustic Insulation 1200mm x 600mm 103.68m2 Pallet

60mm Rockwool Flexi has been designed as a multi-use, dual-purpose acoustic and thermal mineral wool insulation with a unique flexible edge along one side. It is suitable for use all over the home, in pitched roof rafters, framed external walls, internal partitions, intermediate floors, separating walls and floors, and timber suspended ground floors.

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60mm Rockwool Rainscreen Duo Slab 1200mm x 600mm 51.84m2 Pallet

60mm Rainscreen Duo Slab is dual-density insulation specifically developed for use within ventilated cladding systems, as well as sealed systems such as curtain walling. Once installed, the robust outer surface of the slabs, in combination with a factory applied water-repelling agent, acts to resist rain ingress during construction.

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60mm Rockwool RW3 Acoustic Insulation Slab 1200mm x 600mm 51.84m2 Pallet

60mm Rockwool RW3 Slabs can be applied to an array of general building applications for acoustic, thermal and fire protection of partition walls, ceilings, floors and roofs.

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60mm Rockwool RWA45 Acoustic Insulation Slab 1200 x 600mm 92.16m2 Pallet

60mm Rockwool RWA45 has been developed for thermal, acoustic and fire performance in a range of construction types. It is suitable for applications on partition walls, ceilings, floors and roofs.

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70mm Rockwool Flexi Slab Acoustic Insulation 1200mm x 600mm 92.16m2 Pallet

70mm Rockwool Flexi has been designed as a multi-use, dual-purpose acoustic and thermal mineral wool insulation with a unique flexible edge along one side. It is suitable for use all over the home, in pitched roof rafters, framed external walls, internal partitions, intermediate floors, separating walls and floors, and timber suspended ground floors.

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75mm Knauf Rocksilk RS45 Building Insulation Slab 1200mm x 600mm 4.32m2 Pack

75mm Knauf Insulation Rocksilk RS45 is a Rock Mineral Wool slab, designed for use in multiple thermal and acoustic applications. It is non-combustible with the best possible Euroclass A1 reaction to fire classification.

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75mm Rockwool Rainscreen Duo Slab 1200mm x 600mm 51.84m2 Pallet

75mm Rainscreen Duo Slab is dual-density insulation specifically developed for use within ventilated cladding systems, as well as sealed systems such as curtain walling. Once installed, the robust outer surface of the slabs, in combination with a factory applied water-repelling agent, acts to resist rain ingress during construction.

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75mm Rockwool RW3 Acoustic Insulation Slab 1200mm x 600mm 51.84m2 Pallet

75mm Rockwool RW3 Slabs can be applied to an array of general building applications for acoustic, thermal and fire protection of partition walls, ceilings, floors and roofs.

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75mm Rockwool RW4 Acoustic Insulation Slab 1200mm x 600mm 46.08m2 Pallet

75mm Rockwool RW4 Slabs can be applied to an array of general building applications for acoustic, thermal and fire protection of partition walls, ceilings, floors and roofs.

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75mm Rockwool RW5 Acoustic Insulation Slab 1200mm x 600mm 43.20m2 Pallet

75mm Rockwool RW5 Slabs can be applied to an array of general building applications for acoustic, thermal and fire protection of partition walls, ceilings, floors and roofs.

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90mm Rockwool Flexi Slab Acoustic Insulation 1200mm x 600mm 86.40m2 Pallet

90mm Rockwool Flexi has been designed as a multi-use, dual-purpose acoustic and thermal mineral wool insulation with a unique flexible edge along one side. It is suitable for use all over the home, in pitched roof rafters, framed external walls, internal partitions, intermediate floors, separating walls and floors, and timber suspended ground floors.

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90mm Superglass 32 Timber & Rafter Roll Insulation 4.45m2 Roll

90mm Superglass 32 Timber & Rafter Roll covers 4.45m2, providing snug and energy-saving insulation between timbers and rafters.

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140mm Superglass 32 Timber & Rafter Roll Insulation 3.19m2 Roll

140mm Superglass 32 Timber & Rafter Roll covers 3.19m2, providing snug and energy-saving insulation between timbers and rafters

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150mm Isover CWS 36 Cavity Wall Slab 3.28m2 Pack

150mm Isover CWS 36 Cavity Wall Slab offers excellent thermal insulation for cavity walls, effectively reducing heat loss and boosting energy efficiency. Lightweight and easy to install, it delivers reliable, long-lasting performance.

£26.91£32.29 Ex VATInc VAT
£8.20£9.84 Per m2
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