30mm Insulation Board

The 30mm insulation board is a rigid insulation board used to reduce heat transfer through parts of a building. It is thicker than the very thin upgrade layers, but still thin enough to fit where space is limited.

This thickness is commonly specified where you require noticeable thermal improvement without redesigning the whole build-up.

What is 30mm thick insulation board?

An insulation 30mm thickness board is 30mm deep. The material inside the board is meant to trap still air or limit heat transfer.

Heat conducts more readily through dense materials like masonry or timber than through still air or engineered insulation cores. A 30mm insulation board thickness provides greater thermal resistance than thinner layers.

Performance, strength, and moisture behaviour can vary between products even at the same thickness. This is primarily due to the differences in thermal conductivity, density, and moisture resistance.

What is thick 30mm insulation board used for?

A 30mm thick insulation board can be installed:

• Behind internal wall linings, where thicker insulation would unacceptably reduce internal space.
• In stud walls before plasterboard to improve thermal comfort and reduce cold surface temperatures.
• Over solid walls or floors as part of a layered insulation build-up, where additional layers meet structural and thermal requirements.
• Around junctions, reveals, and service zones to reduce local heat loss.

30mm boards are rarely the only insulation layer in most build-ups. They usually act as a supplementary layer alongside thicker primary insulation. In floor build-ups, 30mm insulation is typically used as a supplementary layer rather than the primary thermal insulation.

Types of 30mm insulation board

30mm insulation boards are sold in the form of:

EPS Insulation (expanded polystyrene)

EPS is a lightweight foam made from fused expanded beads. Tiny gaps between the beads trap air, slowing heat transfer. EPS is easy to cut and simple to handle. These boards are commonly used in walls, as backing layers, and in floors when an appropriate EPS grade is specified for load-bearing conditions.

XPS insulation (extruded polystyrene)

XPS is denser than EPS, and it also has a more uniform internal structure. This gives it higher compressive strength and better moisture resistance. XPS boards at 30mm are often chosen for floors or areas where contact with moisture or higher loads is expected.

Phenolic Insulation foam

Phenolic boards use a rigid polymer foam that delivers strong thermal performance for its thickness. A 30mm phenolic board can achieve lower U-values than some thicker, lower-performance materials. Use these in tight build-ups with demanding insulation targets.

PIR Insulation (polyisocyanurate)

PIR boards are defined by a rigid foam core faced with aluminium foil facings. The foil helps limit radiative heat transfer when installed as part of a sealed system. PIR is used across wall, floor, and roof structures, and offers a good balance of performance and practicality.

Kingspan Optim-R VIP (vacuum insulated panel)

VIP boards are a specialist option. They contain a sealed core under vacuum, which removes most of the air and drastically slows heat transfer. This makes 30mm insulation boards in VIP form very effective, where thickness cannot be increased. They must not be cut or punctured, as damage reduces performance.