What is Insulated Plasterboard?
Standard plasterboard with rigid insulation already bonded to the back - usually PIR foam or EPS. One product, two jobs done. Instead of battling with separate insulation batts, vapor barriers, and boarding, you're getting everything in one hit.
The insulation layer (20-100mm thick) is factory-bonded to 12.5mm plasterboard. No gaps, no thermal bridging, no arguments about who's responsible for what.
Why Contractors Are Making the Switch
Time Savings
What used to take two days now takes just one. Insulated plasterboard simplifies installation by combining insulation and plasterboard in a single product. That means fewer steps, fewer materials, and less time on site. You’ll reduce labor costs and speed up project turnaround — allowing you to take on more jobs, more profitably.
Better Performance for Clients
Insulated plasterboard achieves impressive U-values as low as 0.18–0.30 W/m²K, making compliance with Part L of Building Regulations straightforward. Clients enjoy significantly reduced heat loss — often seeing 20–30% savings on energy bills. The result? Warmer homes, lower running costs, and more word-of-mouth recommendations.
Less Site Hassle
Forget juggling insulation batts, vapour barriers, and awkward fits. Insulated boards arrive ready to install — with thermal insulation and plasterboard in one sheet. That means less waste, minimal thermal bridging, reduced storage needs, and fewer trades clashing onsite. It’s a smoother build process from start to finish.
Types and When to Use Each
| Type | Thermal Conductivity | Best For | Price Point |
|---|---|---|---|
| PIR-Backed (Kingspan K118) | 0.022 W/mK | Period properties, tight spaces, premium jobs | Higher |
| EPS-Backed | 0.035 W/mK | Standard renovation, budget-conscious clients | Lower |
| Phenolic Foam | 0.018 W/mK | Specialist applications, maximum performance | Highest |
PIR-Backed - The Premium Choice (Kingspan K118)
Kingspan K118 is the industry standard for PIR-backed insulated plasterboard. Best thermal performance in less thickness - available in 27mm to 102.5mm total thickness. Perfect for period properties where every millimeter counts. Kingspan's factory-bonded construction eliminates installation gaps.
EPS-Backed - Good Value
Expanded Polystyrene (EPS) insulated boards offer reliable thermal performance at an affordable price. They're an excellent choice for standard domestic renovation projects where cost is a key factor. While not the highest performing option, EPS boards still meet regulatory requirements for many wall and ceiling applications. Lightweight, easy to handle, and simple to cut, they’re a favorite for budget-conscious installs that still demand dependable insulation.
Phenolic Foam - Specialist Only
Phenolic foam-backed plasterboards deliver exceptional thermal performance, with some of the lowest lambda values available (as low as 0.020 W/mK). This means you can achieve high levels of insulation with minimal thickness — ideal for projects with tight space constraints or strict regulatory standards. While they come at a premium price, phenolic boards are often the only viable option for high-spec builds, passive houses, or heritage renovations where space-saving and efficiency are critical.
Installation Methods
Dot and Dab - Quick and Reliable
For most internal walls using products like Kingspan K118. Key is getting adhesive coverage right - 10 dabs per square meter. Kingspan recommends their Kooltherm adhesive for best results. Check wall flatness first (max 10mm out over 2m).
Mechanical Fixing - When You Need Security
Uneven walls or heavy boards. Kingspan K118 requires 65mm screws minimum due to insulation thickness. Hit wall structure, not just old plaster. Good detector essential as PIR foam can mask wall structure.
Batten Systems - Maximum Performance
For Passivhaus standards or deep retrofits. More complex but gives best results.
Material Costs:
- PIR-backed: £12-18 per m²
- EPS-backed: £8-12 per m²
- Installation: £15-25 per m²
Client Returns:
- Heating cost reduction: 20-30%
- Payback period: 6-10 years
- Property value increase: £10-20 per m²
Best Applications
Solid Wall Houses
Victorian terraces, 1930s semis - anywhere solid brick walls are losing heat. Often the only practical solution when external insulation isn't possible.
Conversions and Extensions
- Loft conversions
- Garage conversions
- Basement improvements
- New habitable spaces
Whole House Retrofits
Fits perfectly into fabric-first approach for comprehensive energy upgrades.
Common Mistakes to Avoid
Don't Ignore Ventilation
Better insulation = tighter buildings = need proper ventilation. Clients might need mechanical ventilation in wet areas. When you dramatically improve the thermal envelope, the building becomes much more airtight, which means less natural air exchange. This is great for energy efficiency but can lead to humidity problems, especially in kitchens, bathrooms, and utility rooms. Make sure to discuss ventilation requirements with clients upfront - they might need extractor fans upgraded or even mechanical ventilation with heat recovery (MVHR) systems. Factor ventilation costs into your quotes to avoid surprises later.
Get Vapor Control Right
Seal edges and penetrations properly or you'll get condensation problems later. Kingspan K118 has good vapor resistance properties, but it's only as good as your installation. Pay special attention to junctions with floors, ceilings, and around windows where different materials meet. Use appropriate sealants and tapes for these critical areas. Don't forget penetrations for electrical outlets, switches, and pipe runs - these need proper sealing too. Poor vapor control can lead to interstitial condensation inside the wall build-up, which you won't see until it becomes a serious problem.
Check Existing Wall First
Won't fix underlying damp problems. Sort wall issues first or you'll be back later. Before installing any insulated plasterboard, do a proper survey of the existing wall condition. Look for signs of rising damp, penetrating damp, or structural issues that need addressing. If there's existing moisture in the wall, adding insulation will change the thermal dynamics and could make problems worse. Use a moisture meter to check different areas, especially near ground level and around windows. It's better to spend time fixing underlying issues now than to strip everything out and start again in six months when damp problems emerge.
Storage and Handling
Heavier than standard board. Plan storage (flat and dry) and factor extra handling into pricing. A sheet of Kingspan K118 62.5mm weighs significantly more than standard plasterboard - you're looking at around 18-20kg per sheet compared to 12kg for standard board. This affects everything from delivery to installation - you'll need more people for handling, proper storage racks to keep sheets flat, and potentially different cutting equipment. Stack sheets properly with full support to prevent sagging or damage to the insulation layer. Damaged boards can't be used, so handle with care and protect edges during transport and storage.
Don't Ignore Ventilation
Better insulation = tighter buildings = need proper ventilation. Clients might need mechanical ventilation in wet areas. When you dramatically improve the thermal envelope, the building becomes much more airtight, which means less natural air exchange. This is great for energy efficiency but can lead to humidity problems, especially in kitchens, bathrooms, and utility rooms. Make sure to discuss ventilation requirements with clients upfront - they might need extractor fans upgraded or even mechanical ventilation with heat recovery (MVHR) systems. Factor ventilation costs into your quotes to avoid surprises later.
Get Vapor Control Right
Seal edges and penetrations properly or you'll get condensation problems later. Kingspan K118 has good vapor resistance properties, but it's only as good as your installation. Pay special attention to junctions with floors, ceilings, and around windows where different materials meet. Use appropriate sealants and tapes for these critical areas. Don't forget penetrations for electrical outlets, switches, and pipe runs - these need proper sealing too. Poor vapor control can lead to interstitial condensation inside the wall build-up, which you won't see until it becomes a serious problem.
Check Existing Wall First
Won't fix underlying damp problems. Sort wall issues first or you'll be back later. Before installing any insulated plasterboard, do a proper survey of the existing wall condition. Look for signs of rising damp, penetrating damp, or structural issues that need addressing. If there's existing moisture in the wall, adding insulation will change the thermal dynamics and could make problems worse. Use a moisture meter to check different areas, especially near ground level and around windows. It's better to spend time fixing underlying issues now than to strip everything out and start again in six months when damp problems emerge.
Storage and Handling
Heavier than standard board. Plan storage (flat and dry) and factor extra handling into pricing. A sheet of Kingspan K118 62.5mm weighs significantly more than standard plasterboard - you're looking at around 18-20kg per sheet compared to 12kg for standard board. This affects everything from delivery to installation - you'll need more people for handling, proper storage racks to keep sheets flat, and potentially different cutting equipment. Stack sheets properly with full support to prevent sagging or damage to the insulation layer. Damaged boards can't be used, so handle with care and protect edges during transport and storage.
Kingspan Insulated Plasterboard Product Range - Available in Stock at MP MORAN
For contractors looking for reliable, high-performance insulated plasterboard solutions, MP MORAN stocks the complete Kingspan range:
Kingspan K118 Insulated Plasterboard
The Industry Standard for PIR-Backed Performance
Why Choose Kingspan K118 from MP MORAN?
Reliable Stock Levels: We maintain consistent stock across all popular thicknesses
Technical Support: Our team can help with U-value calculations and Building Control submissions
Competitive Pricing: Volume discounts available for larger projects
Fast Delivery: Same-day delivery available within our catchment area
Quality Assurance: All products come with full manufacturer warranties