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120mm Celotex XR4120 PIR Insulation Board 2400mm x 1200mm (8′ x 4′) 2.88m2
120mm Celotex XR4120 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.
£51.94£62.33 Ex VATInc VAT£18.03£21.64 Per M2 Add to cart -
120mm Ecotherm Eco-Versal Rigid PIR Insulation Board 2400mm x 1200mm (8′ x 4′) 2.88m2
120mm 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.
£52.08£62.50 Ex VATInc VAT£18.08£21.70 Per M2 Add to cart -
120mm Kingspan GreenGuard GG300 R Rigid Extruded Polystyrene Insulation Board 1250mm x 600mm Pack of 3 (2.25m2)
120mm 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/m·K
£59.33£71.20 Ex VATInc VAT£26.37£31.64 Per M2 Add to cart -
120mm Kingspan Kooltherm K103 Insulation Floorboard 2400mm x1200mm Pack of 2 (5.76m2)
120mm Kooltherm K103 is a premium phenolic core floor insulation solution, designed to deliver exceptional performance with solid concrete or suspended timber floors.
£265.38£318.46 Ex VATInc VAT£46.07£55.28 Per M2 Add to cart -
120mm Kingspan Kooltherm K107 Pitched Roof Board 2400mm x 1200mm Pack of 2 (5.76m2)
120mm 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.
£265.38£318.46 Ex VATInc VAT£46.07£55.28 Per M2 Add to cart -
120mm Kingspan Kooltherm K112 Framing Insulation Board 2400mm x 1200mm Pack of 2 (5.76m2)
120mm Kingspan Kooltherm K112 Framing Board is a premium performance insulation with a fibre-free rigid thermoset phenolic core. It is used to insulate timber and steel framing systems with thermal conductivity of just 0.019 W/mK across all thicknesses.
£333.92£400.70 Ex VATInc VAT£57.97£69.56 Per M2 Add to cart -
120mm Kingspan Thermaroof TR24 Flat Roof PIR Insulation Board 1200mm x 600mm Pack of 4 (2.88m2)
120mm 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.
£114.93£137.92 Ex VATInc VAT£39.91£47.89 Per M2 Add to cart -
120mm Kingspan Thermaroof TR26 PIR Insulation Board 2400mm x 1200mm (8′ x 4′) Pack of 2 (5.76m2)
120mm 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.
£200.81£240.97 Ex VATInc VAT£34.86£41.83 Per M2 Add to cart -
120mm Kingspan Thermaroof TR27 PIR Insulation Board 1200mm x 1200mm Pack of 4 (5.76m2)
120mm 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.
£205.95£247.14 Ex VATInc VAT£35.76£42.91 Per M2 Add to cart -
120mm Recticel Eurothane GP PIR Insulation Board 2400mm x 1200mm (8′ x 4′) 2.88m2
120mm 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.
£49.31£59.17 Ex VATInc VAT£17.12£20.54 Per M2 Add to cart
120mm Insulation Board
A 120mm insulation board is a thick layer of rigid insulation used where low heat loss is required and sufficient installation depth is available. At 120mm thickness, the insulation forms a significant part of the building’s thermal envelope, helping structures meet modern energy efficiency standards.
What is 120mm thick insulation board?
120mm thick insulation board has an insulation depth of approximately 120mm from face to face. The board is rigid, meaning it keeps its shape and fits tightly between or against building elements.
Many 120mm insulation boards use a closed-cell structure, where gas trapped within sealed cells slows heat transfer.
A 120mm insulation thickness board is usually preferred when designers want to achieve low U-values. It also comes in handy for upgrading older buildings susceptible to high heat leakage. It is commonly specified for refurbishment projects, extensions, and high-spec new builds with demanding energy performance targets.
What is 120mm insulation thickness board used for?
An insulation 120mm thickness board is used in areas with high heat loss or where building regulations push performance higher. These can be:
- Flat roofs, especially warm roof systems using a 120mm flat roof insulation board
- Pitched roofs, between and over rafters
- Floors, including solid or suspended floor subject to regular load
- Internal masonry walls, where space allows for deep lining
- Framing walls, timber or metal stud
- Cladding systems, as part of an external wall build-up
120mm insulation board significantly contribute to improved thermal comfort and heat reduction when correctly installed. However, to maintain performance, you must detail it carefully around junctions, fixings, and edges.
Types of 120mm insulation board
120mm insulation boards are available in these common types:
PIR insulation (Polyisocyanurate)
120mm PIR insulation board offers strong thermal performance for its thickness. It balances cost, performance, and availability, which is why it suits most general building work – whether walls, roofs, or floors.
Phenolic insulation Foam Board
Phenolic boards offer very high thermal performance for the same depth and slightly better insulation than PIR at 120mm. They are often preferred where performance targets are strict – for example, internal wall linings on refurb projects.
XPS insulation (Extruded Polystyrene)
XPS panels do not insulate as well as PIR or phenolic at the same thickness. However, XPS offers superior moisture resistance and compressive strength. It is often used below ground or in floors where compressive strength matters more than maximum thermal value.
Benefits of insulation 120mm board
Installing 120mm insulation boards:
- Provides a significant reduction in heat loss.
- Helps meet demanding U-value targets.
- Improves thermal comfort and temperature stability.
- Reduces heating demand over the life of the building.
- Suits walls, roofs, and floors when space allows.
FAQ
Where to buy 120mm insulation board?
You can buy 120mm insulation board online from Insulation Wholesale. We stock multiple brands and materials and supply both small orders and large site quantities. Our team supports trade buyers with trade discounts, pallet deals, and fast nationwide delivery straight to your site.
How to cut 120mm insulation board?
Use an insulation saw or fine-toothed hand saw to achieve clean, square cuts. Score the facing first if the board is foil-faced, then cut steadily without forcing the blade.
How to install 120mm insulation board in a cavity wall?
- Fit your insulation 120mm thick board tightly so it sits flat against the inner leaf.
- Stagger the joints and tape them where required.
- Wall ties should be long enough for the cavity width.
What is the thermal conductivity of 120mm insulation board?
Thermal conductivity (λ-value) depends on the insulation material:
- PIR boards: around 0.022 W/m.K
- Phenolic foam boards: 0.018–0.020 W/m.K
- XPS boards: 0.029–0.034 W/m.K
The lower the number, the better the insulation. The thickness determines how much that performance adds up across the wall, roof, or floor.
