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:
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 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.
At Insulation Wholesale, you can purchase 52.5mm Insulation Board at low wholesale prices with fast delivery for most of items within 2-5 days. Competitive rates guaranteed.
FAQ
Where to buy a 52.5mm insulation board?
You can buy insulation board 52.5mm thick online from Insulation Wholesale. We stock a range of PIR and phenolic factory‑bonded boards that are UK stock, so you are assured of fast nationwide delivery to your site. Our team offers competitive pricing with trade discounts and pallet deals, and we are happy to help with a fast quote so you know costs upfront.
How to cut 52.5mm insulation board?
Cutting 52.5mm insulated boards is straightforward if you do it right:
Mark the cut line with a straight edge.
Use a fine‑toothed insulation saw, utility knife, or a circular saw with a fine blade.
Score deeply on both sides before snapping straight. This helps keep edges neat.
Wear your dust mask and eye protection, as foam and plasterboard dust irritates lungs and eyes.
How to install 52.5mm insulation board?
To install insulation 52.5mm thick board:
Clean the wall or ceiling surface and allow it to dry.
Fix timber or metal battens to the surface (typically at 600mm centres).
Push the insulation board against the battens, with the joints butted tightly.
Anchor with drywall screws through the plasterboard into the battens – typically at around 300mm centres, subject to system guidance.
Finish joints with tape and joint compound or skim as normal.
If using adhesive (for dot & dab), ensure you follow manufacturer guidance. Dot & dab should only be used where the substrate is suitable, and manufacturer guidance allows it (especially on solid walls).
This method provides a solid, insulated dry‑lined surface with minimal air gaps.
How effective is 52.5mm insulation board?
A 52.5mm insulation board delivers significantly higher thermal performance than plain plasterboard. Good quality PIR or phenolic boards can show very low thermal conductivity (around 0.019–0.022 W/m.K), meaning heat loss through the board is minimal. This contributes to reduced heat loss and improved thermal comfort.
By using the board, you avoid mistakes that sometimes happen when installing separate insulation and lining. You also maintain a clean internal finish without extra plastering layers.
40mm Celotex PL4040 PIR Insulated Plasterboard is it is suitable for use in roof and internal wall lining applications. Celotex Insulated Plasterboard is a high performance, easy to install PIR insulation board with a paper facing, laminated to a piece of 12.5mm tapered edge plasterboard.
£50.04£60.05Ex VATInc VAT£17.38£20.86Per M2Add to cart
40mm + 12.5mm Kingspan Kooltherm K118 Insulated Plasterboard is a premium performance insulation with a fibre-free rigid thermoset phenolic core. It is an insulated plasterboard for mechanically fixed and adhesively bonded insulated dry-lining th a thermal conductivity of just 0.019 W/mK across all thicknesses.
£1,115.19£1,338.23Ex VATInc VAT£25.81£30.97Per M2Add to cart
52.5mm Unilin Safe-R SR/TB is a high-performance insulation that offers excellent thermal efficiency. Its design ensures quick and secure installation, delivering long-term energy savings and safety compliance.
52.5mm Unilin Safe-R SR/TB-MF Mech Fix Insulated Plasterboard is designed for mechanical fixing, it offers excellent thermal efficiency, easy installation and ready-to-finish surface for walls and ceilings.
52.5mm Unilin Thin-R Thermal Liner Mechanically Fixed XT/TL-MF is a composite insulated panel of Unilin PIR insulation core with a composite foil facing bonded to 12.5mm tapered edge plasterboard for internal walls, sloped roofs and ceilings. XT/TL-MF is only suitable for mechanically fixed applications.
