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100mm Celotex CW4100 Cavity Wall Insulation Board 1200mm x 450mm 3.24m2 Pack of 6 (3.24m2)
100mm Celotex CW4100 Cavity Wall Insulation Board is an easy to install polyisocyanurate (PIR) insulation board with excellent thermal performance, featuring a low emissivity foil facing.
£63.73£76.48 Ex VATInc VAT£19.67£23.60 Per M2 Add to cart -
100mm Celotex GA4100 PIR Insulation Board 2400mm x 1200mm (8′ x 4′) 2.88m2
100mm Celotex GA4100 is a polyisocyanurate (PIR) insulation core with composite aluminium foil facings on both sides. Celotex is a multi-purpose insulation board suitable for use in pitched roofs, ceilings, floors and walls.
£40.17£48.20 Ex VATInc VAT£13.95£16.74 Per M2 Add to cart -
100mm Ecotherm Eco-Versal Rigid PIR Insulation Board 2400mm x 1200mm (8′ x 4′) 2.88m2
100mm Ecotherm Eco-Versal is a polyisocyanurate (PIR) insulation core with composite aluminium foil facings on both sides. Ecotherm Eco-Versal is a multi-purpose insulation board suitable for use in pitched roofs, ceilings, floors and walls.
£40.34£48.41 Ex VATInc VAT£14.01£16.81 Per M2 Add to cart -
100mm Expanded Polystyrene EPS100 Insulation Board 2400mm x 1200mm (8′ x 4′) Pack of 24 (69.12m2)
100mm EPS100, often known as Expanded Polystyrene, is a lightweight foam product produced from tiny polystyrene beads. Due to its high thermal value and simplicity of usage, it is commonly used as one of the most favoured insulation materials in construction.
£502.65£603.18 Ex VATInc VAT£7.27£8.72 Per M2 Add to cart -
100mm Expanded Polystyrene EPS150 Floor Insulation Board 2400mm x 1200mm (8′ x 4′) Pack of 6 (17.28m2)
100mm EPS150, often known as Expanded Polystyrene, is a lightweight foam product produced from tiny polystyrene beads. Due to its high thermal value and simplicity of usage, it is commonly used as one of the most favoured insulation materials in construction.
£192.51£231.01 Ex VATInc VAT£11.14£13.37 Per M2 Add to cart -
100mm Expanded Polystyrene EPS200 Floor Insulation Board 2400mm x 1200mm (8′ x 4′) Pack of 6 (17.28m2)
100mm EPS200, often known as Expanded Polystyrene, is a lightweight foam product produced from tiny polystyrene beads. Due to its high thermal value and simplicity of usage, it is commonly used as one of the most favoured insulation materials in construction.
£340.37£408.44 Ex VATInc VAT£19.70£23.64 Per M2 Add to cart -
100mm Expanded Polystyrene EPS250 Floor Insulation Board 2400mm x 1200mm (8′ x 4′) Pack of 6 (17.28m2)
100mm EPS250, often known as Expanded Polystyrene, is a lightweight foam product produced from tiny polystyrene beads. Due to its high thermal value and simplicity of usage, it is commonly used as one of the most favoured insulation materials in construction.
£374.89£449.87 Ex VATInc VAT£21.70£26.04 Per M2 Add to cart -
100mm Isover Acoustic Partition Insulation Roll – Glass Mineral Wool 11m2
100mm Isover Acoustic Partition Insulation Roll is a glass mineral wooldesigned to reduce sound transmission between walls and floors, creating quieter and more comfortable spaces.
£51.46£61.75 Ex VATInc VAT£4.68£5.62 Per m2 Add to cart -
100mm Isover CWS 32 Cavity Wall Slab 3.28m2 Pack
100mm Isover CWS 32 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.
£37.84£45.41 Ex VATInc VAT£11.54£13.85 Per m2 Add to cart -
100mm Isover CWS 36 Cavity Wall Slab 6.55m2 Pack
100mm 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.
£36.99£44.39 Ex VATInc VAT£5.65£6.78 Per m2 Add to cart -
100mm Isover Spacesaver Insulation Loft Roll 14.13m2
100mm Isover Spacesaver Insulation Loft Roll is an efficient and easy-to-install solution for insulating loft spaces, designed to enhance energy efficiency and home comfort.
£32.79£39.35 Ex VATInc VAT£2.32£2.78 Per m2 Add to cart -
100mm Jablite HP+ 70E External Wall Insulation Board 1200mm x 600mm (4′ X 2′) Pack of 6 (4.32m2)
100mm Jablite HP+ 70E External Wall Insulation Board is designed to enhance thermal efficiency for external walls. It can be bonded or mechanically fixed, providing reliable insulation solution.
£54.70£65.64 Ex VATInc VAT£12.66£15.19 Per M2 Add to cart -
100mm Kingspan GreenGuard GG300 R Rigid Extruded Polystyrene Insulation Board 1250mm x 600mm Pack of 4 (3.00m2)
100mm Kingspan GreenGuard GG300 is a high performance rigid extruded polystyrene insulation. It is used to insulate inverted roofs, basements, car park decks, and heavy-duty commercial, industrial and cold store flooring offering a thermal conductivities as low as 0.033 W/mK.
£64.92£77.90 Ex VATInc VAT£21.64£25.97 Per M2 Add to cart -
100mm Kingspan Kooltherm K103 Insulation Floorboard 2400mm x 1200mm Pack of 3 (8.64m2)
100mm Kooltherm K103 is a premium phenolic core floor insulation solution, designed to deliver exceptional performance with solid concrete or suspended timber floors.
£326.98£392.38 Ex VATInc VAT£37.84£45.41 Per M2 Add to cart -
100mm Kingspan Kooltherm K107 Pitched Roof Board 2400mm x 1200mm Pack of 3 (8.64m2)
100mm Kingspan Kooltherm K107 Pitched Roof Board is a premium performance insulation with a fibre-free rigid thermoset phenolic core. It is used to insulate pitched roofs and attic spaces, and has a thermal conductivity of just 0.019 W/m.K across all thicknesses.
£331.96£398.35 Ex VATInc VAT£38.42£46.10 Per M2 Add to cart -
100mm Kingspan Kooltherm K108 Cavity Board Insulation 1200mm x 450mm Pack of 5 (2.70m2)
100mm Kingspan Kooltherm K108 partial fill cavity wall board is a premium performance lower lambda insulation with a rigid thermoset fibre-free phenolic core. It is faced on both sides with a low emissivity composite foil facing and is used in partially filled cavity walls.
£116.83£140.20 Ex VATInc VAT£43.27£51.92 Per M2 Add to cart -
100mm Kingspan Thermaroof TR24 Flat Roof PIR Insulation Board 1200mm x 600mm Pack of 5 (3.60m2)
100mm Kingspan Thermaroof TR24 is a high performance insulation with a fibre-free rigid thermoset polyisocyanurate (PIR) core. Kingspan Thermaroof is suitable for flat roofs waterproofed with partially bonded torch applied multi-layer bituminous waterproofing.
£127.49£152.99 Ex VATInc VAT£35.41£42.49 Per M2 Add to cart -
100mm Kingspan Thermaroof TR26 PIR Insulation Board 2400mm x 1200mm (8′ x 4′) Pack of 3 (8.64m2)
100mm Kingspan TR26 Thermaroof is high-performance insulation that has a fiber-free rigid thermoset polyisocyanurate (PIR) core. Suitable for flat roof application waterproofed with mechanically fixed single-ply waterproofing.
£267.59£321.11 Ex VATInc VAT£30.97£37.16 Per M2 Add to cart -
100mm Kingspan Thermaroof TR27 PIR Insulation Board 1200mm x 1200mm Pack of 4 (5.76m2)
100mm Kingspan Thermaroof TR27 is a high performance insulation with a fibre-free rigid thermoset polyisocyanurate (PIR) core. It is used to insulate flat roofs waterproofed with fully adhered single-ply, partially bonded built-up felt, mastic asphalt and cold liquid applied waterproofing.
£183.59£220.31 Ex VATInc VAT£31.87£38.24 Per M2 Add to cart -
100mm Knauf Acoustic Insulation Roll – Glass Mineral Wool 12.36m2
100mm Acoustic Insulation Roll from Knauf is a Glass Mineral Wool roll, designed for use in internal wall and floor applications, to offer sound absorption and noise reduction properties.
£54.82£65.78 Ex VATInc VAT£4.44£5.33 Per m2 Add to cart -
100mm Knauf Insulation Loft Roll 44 Combi-Cut 13.89m2 Roll
Knauf Insulation Loft Roll 44 is a non-combustible glass mineral wool roll supplied in a Combi-Cut format. It is designed for use in cold lofts. Manufactured using Knauf Insulation’s unique bio-based binder, ECOSE® Technology.
£29.89£35.87 Ex VATInc VAT£2.15£2.58 Per m2 Add to cart -
100mm ODE Acoustic Roll Insulation 7.8m2 Roll
100mm ODE Insulation Acoustic Roll is designed to reduce sound transmission, making it an ideal solution for creating quieter indoor environments. Its flexible and simple-to-install design effectively absorbs sound, making it perfect for both residential and commercial spaces.
£27.71£33.25 Ex VATInc VAT£3.55£4.26 Per m2 Add to cart -
100mm ODE Insulation Loft Roll 10.83m2
100mm ODE Insulation Loft Roll is a highly effective thermal loft solution for improving home energy efficiency. Made from eco-friendly materials, it offers a simple and effective way to improve comfort while lowering energy costs.
£22.84£27.41 Ex VATInc VAT£2.11£2.53 Per m2 Add to cart -
100mm Recticel Eurothane GP PIR Insulation Board 2400mm x 1200mm (8′ x 4′) 2.88m2
100mm Recticel Eurothane GP is a polyisocyanurate (PIR) insulation core with composite aluminium foil facings on both sides. Recticel is a multi-purpose insulation board suitable for use in pitched roofs, ceilings, floors and walls.
£37.85£45.42 Ex VATInc VAT£13.14£15.77 Per M2 Add to cart -
100mm Recticel Eurowall Partial Cavity Wall Insulation Board 1200mm x 450mm Pack of 10 (5.40m2)
100mm Recticel Eurowall Partial Cavity is an advanced thermal insulation panel tailored for use in cavity wall systems, delivering exceptional energy efficiency and robust performance.
£110.29£132.35 Ex VATInc VAT£20.42£24.50 Per M2 Add to cart -
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 -
100mm Superglass 44 Multi Loft Roll Insulation 12.12m2 Roll
Multi-Roll 44 is a lightweight, non-combustible glass mineral wool roll, designed to provide thermal insulation in lofts. This roll is typically used for insulating loft spaces and cold roofs but can also be used in a multitude of different applications.
£27.35£32.82 Ex VATInc VAT£2.26£2.71 Per m2 Add to cart -
100mm Superglass Acoustic Roll 12 Insulation 12.12m2 Roll
Acoustic Roll 12 is a lightweight, non-combustible glass mineral wool insulation roll. The product is designed to provide thermal and acoustic insulation for several applications, including internal floors and partitions. Manufactured at a minimum density of 12kg/m3.
£45.98£55.18 Ex VATInc VAT£4.03£4.84 Per m2 Add to cart -
100mm Superglass Party Wall Roll 7.85m2
Superglass Party Wall Roll is a lightweight, non-combustible glass mineral wool insulation roll. The flexible roll is cut at 3x455mm widths to fit between standard wall ties spacings and to allow easy installation and minimum on-site cutting and waste. Manufactured at a minimum density of 18kg/m3 .
£66.83£80.20 Ex VATInc VAT£8.51£10.21 Per m2 Add to cart -
100mm Superglass Superwall 32 Cavity Wall Slab 3.28m2 Pack
100mm Superglass Superwall 32 is a British Board of Agrément (BBA) approved, non-combustible and water repellent glass mineral wool insulation cavity wall batt. The flexible batt is supplied at 455mm wide to allow easy installation between standard vertical wall tie spacings and minimum on-site cutting and waste.
£36.34£43.61 Ex VATInc VAT£11.08£13.30 Per m2 Add to cart -
100mm Unilin Safe-R SR/CW Partial Fill Cavity Wall Phenolic Insulation Board 1200mm x 450mm Pallet of 120 (64.80m2)
100mm Unilin Safe-R SR/CW Partial Fill Phenolic Cavity Wall Insulation Board is a high-performance insulation product specifically designed to enhance the thermal efficiency of cavity wall systems.
POA Get a quote -
100mm URSA 32 Cavity Wall Insulation Slab 3.07m2 Pack
100mm URSA Cavity Batt is a lightweight, semi-rigid glass mineral wool slab treated with silicon-based water repellent. It is suitable for use in both fully and partially filled masonry cavity walls up to 25m high.
£30.52£36.62 Ex VATInc VAT£9.94£11.93 Per m2 Add to cart -
100mm URSA 35 Cavity Wall Insulation Slab 3.69m2 Pack
100mm URSA Cavity Batt is a lightweight, semi-rigid glass mineral wool slab treated with silicon-based water repellent. It is suitable for use in both fully and partially filled masonry cavity walls up to 25m high.
£21.66£25.99 Ex VATInc VAT£5.87£7.04 Per m2 Add to cart -
100mm URSA Acoustic Partition Roll Insulation 7.20m2 Roll
100mm URSA Acoustic Roll is a lightweight, non-combustible, unfaced glass mineral wool product for use as acoustic insulation in timber or metal framed internal partition walls, timber or metal framed separating walls and timber separating floors.
£29.98£35.98 Ex VATInc VAT£4.16£4.99 Per m2 Add to cart
100mm Insulation
100mm insulation is insulation that is 100 millimetres deep, selected for its strong balance between thermal performance and construction depth. It is widely used because it reduces heat loss significantly and fits standard wall, roof, and floor build-ups.
What is insulation 100mm?
100mm insulation refers to insulation with a nominal thickness of 100 millimetres. It is commonly specified to support compliance with Approved Document Part L of the Building Regulations.
At 100mm insulation thickness, the material increases thermal resistance within the construction to lower heat transfer by conduction and contribute to improved component U-values. When correctly detailed and installed, this depth helps the building fabric meet or exceed the limiting values set out under Part L.
100mm rigid insulation boards are dimensionally stable. They ensure consistent thickness and sustained contact with adjacent elements. This reduces the risk of air gaps and thermal bypass, and localised heat loss, which can undermine calculated performance. As a result, insulation at 100mm is regularly adopted in Part L–compliant structural specifications, where it delivers predictable, repeatable performance.
What is 100mm thick insulation used for?
100mm thick insulation is used where you need solid thermal control but still have space limits. It is common in:
- Timber and metal stud walls
- Solid walls during upgrades
- Flat and pitched roofs (between joists or rafters)
- Floors where heat loss is a concern
Because insulation 100mm thick fits between standard structural depths, it is practical for both new builds and refurbishment work.
Types of 100mm insulation
Each type of 100mm Insulation works to keep heat in and cold out. Here’s a quick guide to the most readily available types:
1. PIR insulation boards
This is the “high-performance” option that punches above its weight. Slim and rigid, they keep heat in without taking up much space. PIR panels are perfect for walls and flat roofs where every millimetre of space counts.
2. Mineral wool insulation / Rockwool
The tough, fire-safe option. They are made from spun rock or glass. Rockwool insulation keeps warmth in and dampens noise. It is flexible and easy to tuck into walls, floors, and ceilings. A favourite for tricky spaces.
3. EPS insulation Boards
Light and easy to cut. Expanded polystyrene is often used in cavity walls and under floors. It delivers reliable insulation by keeping the cold out.
4. XPS insulation boards
The heavyweight water-fighter. Strong and moisture-resistant option that keeps its shape. Great for floors and basements. Extruded polystyrene boards are also ideal for flat roofs that see a bit of damp.
5. Glass wool insulation / Fibre Wool Rolls
100m soft insulation that is friendly to handle. Rolls slide neatly between joists and studs. Best choice for lofts, walls, and anywhere an easy-to-fit, dependable solution is needed.
Benefits of 100mm insulation thickness
The main benefit of 100mm insulation is consistency. It delivers reliable thermal resistance without overcomplicating the build. Key advantages include:
- Slows heat flow through walls and roofs
- Helps meet UK energy standards when used correctly
- Reduces cold spots when boards are tightly fitted
- Works well alongside vapour control layers
- Using insulation 100mm also keeps detailing simpler, which lowers the risk of mistakes on site.
Why choose our thick 100mm insulation?
Insulation Wholesale supplies 100mm insulation that meets UK manufacturing standards and is suitable for real building conditions, not just lab tests. Our team focuses on:
- Stocking trusted insulation types
- Clear product information for 100mm insulation panels
- Thicknesses that match common site requirements
- Offering support from a team that understands how 100mm insulation is actually installed
We do not oversell performance. We help you choose what works.
If your project needs a proven, practical insulation depth, 100mm thick insulation is a solid place to start. Browse our range for well-priced options and fast, dependable delivery that fits real site timelines.
FAQ
Where to buy 100mm insulation?
You can buy 100mm insulation online directly from Insulation Wholesale. We stock and supply insulation in standard thicknesses used across UK construction, including 100mm insulation thickness options. Our shop makes it easy to compare products. Browse our site to check availability and get advice from a team that understands site conditions, not just specifications.
How good is 100mm insulation?
On matters insulation, 100mm thickness provides strong resistance to heat movement when installed correctly. Its performance depends on the material, but the thickness itself is enough to make a clear, measurable difference to energy efficiency in most buildings.
How to cut 100mm insulation?
Cut 100mm hard insulation using an insulation saw or hand saw. Measure and cut slightly oversize. Then press it into place. A tight fit matters more than a perfect edge.
How much is 100mm insulation?
100mm insulation boards vary quite a bit in price depending on material and performance. For basic PIR boards, prices are £25–£35 per board (for a full 2400 × 1200mm 100mm insulation board) when buying single units.
Higher-performance or specialist boards can cost more, sometimes £40 or more per m² for premium products. If you buy in bulk, prices often move down further, but expect a rough range of £25–£50+ per board before VAT.
