62.5mm Insulation Board

62.5mm insulation is a common internal upgrade supplied as an insulated plasterboard. It provides a significant improvement in thermal performance without requiring structural modifications.

It is designed to fit within typical internal lining build-ups and makes installing insulation simpler than installing insulation and plasterboard as separate layers. When installed well, the building stays warmer and more comfortable all year round.

What is 62.5mm Thick Insulation Board?

A 62.5mm thick insulation board is a bonded system made up of:

• A rigid PIR or phenolic foam insulation layer, typically 50mm deep.
• A plasterboard face, typically 12.5mm deep.

The insulation layer restricts heat transfer through the material to reduce heat loss in winter and limit heat gain in summer.

The plasterboard side of the panel gives a smooth, skim-ready lining. As a result, a separate plasterboard lining is not required. Because of this, a 62.5mm insulation thickness board reduces installation time compared to separate layers.

What is 62.5mm Insulation Board Thickness Used For?

The 62.5mm thickness insulation board is mainly used for internal wall insulation:

• When external insulation is not possible. (listed buildings or tight boundaries)
• When solid brick or block walls exhibit low internal surface temperatures.
• To improve comfort without changing the exterior of the building.

62.5mm thickness gives a noticeable improvement in U-values compared to thinner boards. It can contribute to U-value improvements of approximately 0.2–0.25 W/m²K, depending on wall construction and detailing.

Despite this thickness, it remains manageable around window reveals and services. This balance explains why 62.5mm insulation boards are common in housing upgrades where deeper insulation is often used elsewhere.

Types of 62.5mm Insulation Board

62.5mm insulated plasterboards are available in two main types:

PIR insulated plasterboard

PIR uses a closed-cell foam structure that resists heat flow very effectively for its thickness. An insulation board 62.5mm thick made with PIR is a good all-round choice for walls and ceilings where space is limited, but performance still matters.

It is lighter than many alternatives, easy to handle on site, and widely used in standard UK internal wall and ceiling detailing.

Phenolic foam insulated plasterboard

Phenolic foam is denser than PIR, for example, Kingspan K118 and performs better at the same depth. It is also more brittle, so take care when cutting or handling to avoid cracks.