70mm Insulation

70mm insulation sits between thin lining insulation and deeper structural insulation layers. It is ideal when a project requires a significant thermal improvement but cannot accommodate the space required for thicker insulation.

It is a suitable choice for refurbishment work, lining upgrades, and tight timber details.

What is 70mm Thick Insulation?

70mm thick insulation, sometimes referred to as insulation thick 70mm, measures exactly 70 millimetres when installed at its nominal thickness.

This depth of insulating material reduces heat transfer by trapping still air (soft products) or by resisting heat flow through rigid foam boards.

While it is 10mm slimmer than 80mm thick insulation, the mechanism at work is the same: less heat escapes, resulting in improved thermal retention within the building.

What is 70mm Insulation Thickness Used For?

70mm insulation boards and slabs are typically used when the build-up will not allow that extra depth. Common uses include:

• Internal wall upgrades where space is tight
• Timber stud partitions
• Warm roof constructions where rafter depth or build-up height is restricted (usually part of a multi-layer build-up)
• Floors above unheated spaces, such as garages or voids

Types of 70mm Insulation

Installers consider placement, fit, moisture risk, and required installation skills when choosing one type of 70mm insulation over another. The types of products available in 70mm insulation thickness include:

70mm soft insulation materials (mineral wool, glass wool): These rely on air pockets and are more tolerant of minor dimensional variation. Therefore, you do not need to cut them to the exact size that fits the space; they can be cut slightly wider or oversized and still fit snugly due to their compressible nature.

70mm hard insulation boards (PIR, phenolic, EPS, XPS): These resist heat flow more strongly per millimetre but demand precise cutting.

70mm Mineral Wool

It is made from spun rock fibres pressed into slabs. It has a dense yet springy structure and holds its shape once fitted.

Works by trapping still air between fibres. Typical thermal conductivity ranges from 0.035 to 0.040 W/m.K. It is noncombustible and vapour-permeable, allowing moisture to pass through the structure.

Best for stud walls, partitions, and floors between joists. Also used where fire resistance and sound control matter as much as heat retention.

70mm Glass Wool

Formed from molten recycled glass spun into a lightweight, fibrous mat. It relies on air pockets to restrict heat flow and has a thermal conductivity of 0.032–0.040 W/m.K.

A compressible material that is common in timber frames, loft slopes, and wall linings, where insulation should friction-fit into place.

70mm PIR Insulation

A rigid foam board with a foil face on each side. Foil facings can help reduce radiant heat transfer when installed adjacent to an air space.

Lightweight yet stiff, it offers strong thermal resistance for its depth, with thermal conductivity of 0.022–0.026 W/m.K.

It provides high thermal resistance in space-constrained areas, such as internal wall linings, warm roofs, and floor build-ups.

70mm Phenolic Insulation

This is a closed-cell foam similar to PIR but with a finer internal structure.

It offers slightly better thermal performance than PIR, typically 0.020–0.023 W/m.K. It is more brittle than PIR and therefore requires careful handling during installation.

Ideal when maximum insulation is needed in the smallest possible depth, especially in projects with strict build-up limits.

70mm EPS Insulation

These are light panels made from expanded polystyrene beads fused together. They are vapour-permeable and dimensionally stable compared to closed-cell foams.

Their thermal conductivity typically ranges from 0.030 to 0.038 W/m.K, depending on grade.

Common in floors and cavity wall systems. Also, for areas that need a balance of insulation and breathability.

70mm XPS Insulation

XPS is a denser form of polystyrene with a smooth, closed-cell surface. It maintains performance even in damp conditions.

Has lower water absorption than EPS with typical thermal conductivity values of approximately 0.029–0.034 W/m.K. Ideal for floors, inverted roofs, and ground-contact areas where moisture resistance is critical.

Benefits of Insulation 70mm Thickness

70mm delivers gains such as:

• Noticeable heat-loss reduction
• Easier detailing around windows and services
• Less disruption in refurb projects
• Compatible with many existing frames
• Improves occupant comfort in addition to lowering U-values

FAQ

Where to buy 70mm insulation

You can buy insulation 70mm online from Insulation Wholesale. We stock both soft and rigid options, supply well-known UK brands, and keep pricing competitive across thicknesses. Our team helps you match the insulation to the build detail, not just the spec sheet, so the correct product is specified and installed the first time.

How to cut 70mm insulation

• Soft insulation: Use a long knife or saw and cut slightly oversize.
• Rigid boards: Score deeply along a straight edge, then snap or saw for clean edges.

Always aim for snug contact, as gaps allow heat to pass through the material more freely.

How much is 70mm insulation?

Prices vary by material. Products offering higher thermal performance per millimetre typically cost more.

• Soft insulation rolls or slabs typically cost £4–£8 per m².
• Rigid foam boards are typically £10–£20 per m², depending on type and brand.

Please note that these price ranges are indicative and significantly vary by brand, specification, and order volume.