52.5mm Insulation Board

A 52.5mm insulation board is a rigid insulated plasterboard panel designed to reduce heat loss through internal walls or ceilings. It is made by attaching a rigid foam insulation core to plasterboard. This provides insulation and a finished plasterboard lining in a single board.

These boards are widely used in UK refurbishment and internal drylining projects because they speed up work and improve comfort inside buildings.

What is 52.5mm thick insulation board?

The 52.5mm thick insulation board is made by bonding 40mm of rigid PIR or phenolic insulation to 12.5mm of plasterboard.

52.5mm phenolic boards tend to have lower thermal conductivity per millimetre than PIR, but PIR is also excellent and widely used.

The two layers are attached, offering insulation and dry-lining in one board – installation is quicker, cleaner, and less prone to error. This type of insulation 52.5mm thickness board offers a measurable improvement in thermal comfort without reducing room space in internal walls or ceilings.

What is 52.5mm thin insulation board used for?

Although 52.5mm is thin compared with full-depth insulation systems, this board:

• Improves thermal performance on internal walls and ceilings.
• Can be fixed on solid masonry walls or installed within timber or metal framing systems.
• Is suitable for internal drylining of sloping ceilings or when used as an internal lining system, not as primary between-rafter insulation unless specified by the system.
• Is often chosen in refurbishment work where the room size is limited to support compliance with Part L requirements.

Types of 52.5mm insulation board

There are two main types of 52.5mm insulation boards commonly available at Insulation Wholesale:

Phenolic Insulation Foam Boards

The insulation core is a rigid phenolic foam bonded to plasterboard. Phenolic has very low thermal conductivity, which means higher thermal resistance per millimetre than many alternatives.

PIR Insulation (Polyisocyanurate)

PIR cores are also rigid and widely used in UK construction. They have excellent thermal resistance and can help achieve target U-values when correctly specified.

Many brands offer 52.5mm PIR bonded boards with foil facings that act as a vapour control layer when correctly sealed.

Each type suits walls and ceilings in homes or commercial spaces. The choice often depends on performance targets and budget. Both types are supplied as factory-bonded, ready-to-install panels.