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Insulation By Thickness Acoustic Thermal
Insulation thickness is a simple way to choose insulation based on the depth of the space you need to fill. This allows you to select the most appropriate material or product range to deliver the performance you need for that required depth. That makes it easier to match the insulation to structures and cavities without forcing or compressing it.
What is insulation by thickness?
Insulation by thickness means selecting an insulating material that matches a required depth. The required depth typically depends on the size of timber or steel framing members. It is also determined by UK Building Regulations and target U-values, as well as existing construction constraints that cannot be altered.
To work properly, insulation must fit the space for which it is designed. If it is thinner than the void, heat can escape around it. If fibrous insulation is over-compressed, the trapped air structure is reduced, leading to a drop in performance. So thickness matters just as much as the material itself.
This approach applies to all insulation types. Mineral wool slabs, glass wool rolls, blown fibre, phenolic foam, PIR, EPS, XPS, and aerogel products are all installed to set depths, and so they can be used correctly in different parts of a building.
What are the different insulation thicknesses used for?
Insulation comes in these common depths:
- Very thin insulation (2–10mm) – usually used for surface upgrades. This includes acoustic layers, thermal laminates, pipe wraps, and specialist products like aerogel, where space is extremely tight.
- Thin to mid-range insulation (12–50mm) – common for internal wall linings, under screeds, between battens, and in service voids, to reduce surface condensation and cold-spot formation. High‑performance foams do more at these depths than fibrous materials.
- Mid-range insulation (60–100mm) – widely used in stud walls, timber floors, warm roofs, and solid wall upgrades. Mostly offered in mineral wool (glass or stone), PIR, and phenolic foam. All can perform reliably when correctly specified and installed.
- Thicker insulation (120–200mm) – typically for roofs, lofts, deep floor zones, and high‑performance wall systems. These depths are about slowing heat flow over time, not just stopping drafts. Loose‑fill and quilt products work well here because they fully fill irregular spaces.
What thicknesses of insulation are there?
Insulation Wholesale stocks insulation thicknesses from 2mm right up to 200mm. Manufacturing constraints and performance requirements determine the depth ranges for each material.
Typical available ranges include:
- Ultra‑thin specialist layers – These are mostly 2–10mm.
- Standard board and slab depths – including 20, 25, 30, 40, and 50mm.
- Common structural fills – Usually 60, 70, 75, 80, 90, 100mm.
- Deep‑fill options – Commonly 120, 140, 150, 170, 200mm.
This wide range allows insulation by thickness to work across refurbishments, extensions, and new builds without structural redesign.
At Insulation Wholesale, you can purchase Insulation By Thickness at low wholesale prices with fast delivery for most of items within 2-5 days. Competitive rates guaranteed.
FAQ
Where to buy insulation by thickness?
You can buy insulation by thickness from Insulation Wholesale. We stock multiple materials across a full depth range, so you can choose the material that best fits your construction build-up, without compromising. Our team helps match insulation thickness to your application, whether for floors, walls, roofs, or specialist applications. We supply UK stock and support both trade and DIY customers with clear advice and reliable delivery.
What insulation thickness is best?
There is no single “best” insulation thickness. The right choice depends on the space available, the target U‑value, and the material used. A thinner high‑performance foam can outperform a thicker fibrous product, while deeper mineral wool can give better sound control and fire resistance. Choose the thickest insulation that fits without compression while complying with UK Building Regulations.
Can different materials be mixed at the same thickness?
Yes, you may combine materials - as long as they are compatible and correctly detailed. You can combine a rigid board layer with mineral wool of the same depth to improve thermal control and sound absorption, for example. The key is to maintain continuity with no air gaps. Do a full vapour control and condensation risk assessment before combining materials.
Insulation By Thickness Range
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3mm Insulation (2)
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5mm Insulation (6)
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6mm Insulation (3)
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8mm Insulation (1)
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9mm Insulation (3)
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10mm Insulation (2)
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12mm Insulation (5)
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15mm Insulation (7)
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18mm Insulation (1)
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20mm Insulation (24)
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25mm Insulation (86)
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27mm Insulation (2)
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30mm Insulation (29)
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37.5mm Insulation (6)
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40mm Insulation (24)
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42.5mm Insulation (1)
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45mm Insulation (2)
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48mm Insulation (2)
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50mm Insulation (62)
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50.5mm Insulation (1)
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52.5mm Insulation (6)
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57.5mm Insulation (1)
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60mm Insulation (40)
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62.5mm Insulation (7)
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65mm Insulation (1)
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70mm Insulation (19)
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72.5mm Insulation (6)
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75mm Insulation (42)
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80mm Insulation (27)
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82.5mm Insulation (4)
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85mm Insulation (2)
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90mm Insulation (25)
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92.5mm Insulation (2)
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100mm Insulation (63)
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110mm Insulation (11)
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115mm Insulation (4)
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120mm Insulation (22)
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125mm Insulation (11)
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130mm Insulation (16)
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140mm Insulation (23)
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150mm Insulation (36)
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165mm Insulation (2)
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180mm Insulation (2)
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200mm Insulation (6)
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100mm Rockwool Flexi Slab Acoustic Insulation 1200mm x 600mm 4.32m2 Pack
100mm 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.
£42.91£51.49 Ex VATInc VAT£9.93£11.92 Per m2 Add to cart -
100mm Rockwool RW3 Acoustic Insulation Slab 1200mm x 600mm 2.88m2 Pack
100mm 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.
£37.01£44.41 Ex VATInc VAT£12.85£15.42 Per m2 Add to cart -
100mm Rockwool RWA45 Acoustic Insulation Slab 1200 x 600mm 2.88m2 Pack
100mm 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.
£23.41£28.09 Ex VATInc VAT£8.13£9.76 Per m2 Add to cart -
140mm Rockwool Flexi Slab Acoustic Insulation 1200mm x 600mm 2.88m2 Pack
140mm 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.
£39.18£47.02 Ex VATInc VAT£13.60£16.32 Per m2 Add to cart -
50mm Rockwool RWA45 Acoustic Insulation Slab 1200 x 600mm 6.48m2 Pack
50mm 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.
£27.94£33.53 Ex VATInc VAT£4.31£5.17 Per m2 Add to cart -
75mm Rockwool RWA45 Acoustic Insulation Slab 1200 x 600mm 4.32m2 Pack
75mm 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.
£27.24£32.69 Ex VATInc VAT£6.31£7.57 Per m2 Add to cart -
100mm Knauf Rocksilk RS45 Building Insulation Slab 1200mm x 600mm 3.6m2 Pack
100mm 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.
POA Get a quote -
100mm Rockwool Rainscreen Duo Slab 1200mm x 600mm 46.08m2 Pallet
100mm 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.
POA Get a quote -
100mm Rockwool RW4 Acoustic Insulation Slab 1200mm x 600mm 34.56 m2 Pallet
100mm 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.
POA Get a quote -
100mm Rockwool RW5 Acoustic Insulation Slab 1200mm x 600mm 34.56m2 Pallet
100mm 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.
POA Get a quote -
125mm Rockwool Rainscreen Duo Slab 1200mm x 600mm 34.56m2 Pallet
125mm 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.
POA Get a quote -
140mm Knauf Rocksilk Flexible Insulation Slab 1200mm x 600mm 2.16m2 Pack
140mm Knauf Insulation Rocksilk Flexible Slab is a Rock Mineral Wool slab, designed for use in multiple thermal and acoustic applications as well as the fire protection of a loft conversion floor. It is non-combustible with the best possible Euroclass A1 reaction to fire classification.
POA Get a quote -
150mm Rockwool Rainscreen Duo Slab 1200mm x 600mm 34.56m2 Pallet
150mm 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.
POA Get a quote -
180mm Rockwool Flexi Slab Acoustic Insulation 1200mm x 600mm 25.92m2 Pallet
180mm 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.
POA Get a quote -
180mm Rockwool Rainscreen Duo Slab 1200mm x 600mm 25.92m2 Pallet
180mm Rainscreen Du 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.
POA Get a quote -
25mm Knauf Rocksilk RS45 Building Insulation Slab 1200mm x 600mm 14.4m2 Pack
25mm 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.
POA Get a quote -
25mm Rockwool RW3 Acoustic Insulation Slab 1200mm x 600mm 138.24m2 Pallet
25mm 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.
POA Get a quote -
25mm Rockwool RW5 Acoustic Insulation Slab 1200mm x 600mm 138.24m2 Pallet
25mm 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.
POA Get a quote -
25mm Rockwool RWA45 Acoustic Insulation Slab 1200 x 600mm 138.24m2 Pallet
25mm 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.
POA Get a quote -
30mm Rockwool RW3 Acoustic Insulation Slab 1200mm x 600mm 129.60m2 Pallet
30mm 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.
POA Get a quote -
30mm Rockwool RW5 Acoustic Insulation Slab 1200mm x 600mm 115.20m2 Pallet
30mm 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.
POA Get a quote -
30mm Rockwool RWA45 Acoustic Insulation Slab 1200 x 600mm 138.24m2 Pallet
30mm 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.
POA Get a quote -
40mm Rockwool RW3 Acoustic Insulation Slab 1200mm x 600mm 86.40m2 Pallet
40mm 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.
POA Get a quote -
40mm Rockwool RWA45 Acoustic Insulation Slab 1200 x 600mm 138.24m2 Pallet
40mm 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.
POA Get a quote -
50mm Knauf Rocksilk RS45 Building Insulation Slab 1200mm x 600mm 7.2m2 Pack
50mm 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.
POA Get a quote -
50mm Rockwool Ablative Coated Batt 1200mm x 600mm x 0.72m2
50mm 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 and floors and flexible walls.
£23.41£28.09 Ex VATInc VAT Add to cart -
50mm Rockwool Flexi Slab Acoustic Insulation 1200mm x 600mm 8.64m2 Pack
50mm 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.
POA Get a quote -
50mm Rockwool Rainscreen Duo Slab 1200mm x 600mm 69.12m2 Pallet
50mm 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.
POA Get a quote -
50mm Rockwool RW3 Acoustic Insulation Slab 1200mm x 600mm 69.12m2 Pallet
50mm 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.
POA Get a quote -
50mm Rockwool RW4 Acoustic Insulation Slab 1200mm x 600mm 69.12 m2 Pallet
50mm 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.
POA Get a quote -
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.
POA Get a quote -
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 Add to cart -
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.
POA Get a quote -
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.
POA Get a quote -
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.
POA Get a quote -
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.
POA Get a quote
