Split your purchase of £23.50 into 3 with no sign-up fees or late fees.
£7.83
today
£7.83
1 month
£7.83
2 months
How it works
Choose PayPal at checkout to pay later with Pay in 3.
Complete your purchase with the first payment today.
Remaining payments are taken automatically.
Pay in 3 is a form of credit, so carefully consider whether the purchase is affordable and how you will make the repayments. Be aware of the possible impact of using Pay in 3 and of missing payments, including making other borrowing more difficult or more expensive. Pay in 3 eligibility is subject to status and approval. 18+ UK residents only. Available for purchases of £30 to £2,000. Terms and conditions apply. PayPal Pay in 3 is a trading name of PayPal (Europe) S.à r.l. et Cie, S.C.A. 22-24 Boulevard Royal L-2449, Luxembourg.
Get what you need for your next project, choose how you pay.
Pay in 30 days
£23.50
Pay in full
Klarna's Pay in 30 days is an unregulated credit agreement. Borrowing more than you can afford or paying late may negatively impact your financial status and ability to obtain credit. 18+, UK residents only. Subject to status. T&Cs and late fees apply.
Pay over time
£7.83 Every 30 days
Pay in 3
£7.83
today
£7.83
in 30 days
£7.83
in 60 days
Klarna's Pay in 3 is an unregulated credit agreement. Borrowing more than you can afford or paying late may negatively impact your financial status and ability to obtain credit. 18+, UK residents only. Subject to status. T&Cs and late fees apply.
How it works
At checkout select Klarna.
Choose your payment plan.
Different payment plans may be shown depending on the purchase amount and credit score.
Complete your checkout.
The amount will be charged based on the payment plan you chose.
Split your purchase of £23.50 into 4 with no sign-up fees or late fees. Your purchase will be split into 4 payments, payable every 2 weeks
£5.88
today
£5.88
second payment
£5.88
third payment
£5.88
fourth payment
How it works
Choose Clearpay at checkout to pay later with Pay in 4.
Complete your purchase with the first payment today.
Remaining payments are taken automatically.
Clearpay is unregulated credit. Use responsibly. 18+, T&Cs and late fees apply at clearpay.co.uk/en-GB
Clearpay lends you a fixed amount of credit so you can pay for your purchase over 4 instalments, due every 2 weeks. Ensure you can make repayments on time. You must be 18+ and a permanent UK resident (excl Channel Islands). Clearpay charges a £6 late fee for each late instalment and a further £6 if it’s still unpaid 7 days later. Late fees are capped at £6 for orders under £24 and the lower of £24 or 25% of the order value for orders over £24. Missed payments may affect your ability to use Clearpay in the future and your details may be passed onto a debt collection agency working on Clearpay’s behalf. Clearpay is credit that is not regulated by the Financial Conduct Authority. T&Cs and other eligibility criteria apply at clearpay.co.uk/terms
Foil-faced PIR insulation board, measuring 50mm in thickness for use in floors, walls, and roofs.
Manufactured as part of the GA4000 range, it is intended for general application, meaning it can be confidently specified across a broad spectrum of build-ups without the need for specialist products.
The board consists of a rigid polyisocyanurate (PIR) core faced with low-emissivity foil on both sides. This construction provides excellent thermal resistance, helping to reduce heat loss through the building fabric while also acting as a vapour control layer.
At 50mm thick, this is the thinnest GA option, providing effective insulation while minimising loss of space.
Features & Benefits
Thermal conductivity (0.022 W/m·K): Reduces the thickness required to meet U-value targets.
Low-emissivity foil facings: Reflect radiant heat across cavity air spaces, improving overall efficiency.
GA4000 range (general application): Suitable for versatile use across roofs, walls, and floors.
Rigid PIR core: Lightweight yet robust, easy to cut and install with standard tools.
Moisture resistance: Closed-cell core prevents water uptake and preserves thermal performance.
Environmental credentials: Zero ODP, low GWP blowing agent, and BRE Green Guide Rating A.
BBA certified (17/5405, 16/5352): Independent assurance of performance across roofs, walls, and floors.
Board size 2400 × 1200mm: Supplied in the industry-standard sheet size for insulation, ensuring compatibility across typical build-ups.
Thickness 50mm: Thinnest GA option, ideal for retrofit and space-constrained projects.
Applications
General insulation: Versatile board suitable for a wide range of domestic and commercial applications.
Beam and block flooring: High-performance PIR boards are installed over the structural floor to provide a continuous thermal barrier beneath sand and cement or liquid screeds.
Concrete slab and oversite floors: High compressive strength enables boards to be laid directly over or under ground-bearing slabs to meet specific U-value targets in new-build construction.
Suspended timber floors: Rigid boards are cut-to-fit and friction-supported between floor joists to significantly reduce heat loss through ventilated sub-floor voids.
Concrete slab overlays: Low thermal conductivity allows for the upgrade of existing concrete floors where minimal thickness is required to maintain room height and door clearances.
Underfloor heating systems: Reflective foil facers on both sides of the board enhance the efficiency of underfloor heating by reflecting heat upwards into the living space.
Timber frame wall insulation: Rigid PIR boards are friction-fitted between timber studs to provide high-performance thermal resistance within a narrow wall profile.
Masonry wall dry-lining: Low-conductivity boards are fixed to the internal face of solid or cavity masonry walls to significantly improve thermal retention in retrofit projects.
Pitched roof insulation: Versatile 50mm boards are installed between or over rafters to create a high-performance thermal envelope in ventilated or unventilated roof voids.
Flat roof insulation: High compressive strength allows for installation beneath a waterproof membrane or over a structural deck to provide a stable, thermally efficient roof covering.
Summerhouse and garden room insulation: High-performance 0.022 W/mK thermal conductivity provides maximum heat retention within timber stud walls and roof rafters.
Installation Guidance
Measuring and cutting: Measure the aperture accurately and cut the board using a fine-toothed saw or sharp knife for a tight friction fit.
Positioning and fixing: Place the board securely against the substrate or between structural members, ensuring no gaps are left between adjacent boards.
Sealing joints: Apply high-quality aluminium foil tape to all board joints to maintain the integrity of the vapour control layer.
Mechanical attachment: Use appropriate insulation fixings or adhesive as specified by the project requirements to secure boards to walls or ceilings.
Fire lining (wall applications): Ensure the insulation used in wall applications is covered with a fire-rated lining, such as 12.5mm plasterboard, to meet safety requirements.
Compliance & Performance
Thermal conductivity: Achieves a declared Lambda value of 0.022 W/mK in accordance with BS EN 13165.
Compressive strength: Rated at ≥140 kPa when tested to BS EN 826, making it suitable for floor applications subject to light loads.
UK Building Regulations Part L: Helps meet Part L (Fuel and Power) requirements; however, 50mm may require additional layers to meet specific new-build U-value targets.
UK Building Regulations Part B: Rated as Euroclass E in accordance with BS EN 13501-1; this material is combustible and must be installed behind a fire-rated lining in wall applications.
UK Building Regulations Part C: Requires the use of a separate Vapour Control Layer (VCL) and taped joints in many applications to prevent interstitial condensation as per Part C (Site preparation and resistance to contaminants and moisture).
Environmental impact: Zero Ozone Depletion Potential (ODP) and low Global Warming Potential (GWP) during the manufacturing process.
Important note: UK Building Regulations vary by project and location; always consult a Building Control Officer or Architect to confirm this thickness meets the legal U-value requirements for your specific build.
What Customers Are Saying
Customers rate the 50mm Celotex highly for internal wall insulation projects where the thinner profile is essential to preserve room dimensions. Reviewers note the boards are easy to cut with a standard saw and fit snugly between battens. The foil facing is praised for its vapour barrier properties, reducing the need for separate membrane installation. Delivery and packaging receive positive mentions across all three reviews.
Summarised by AI from customer reviews.
Delivery & Returns Information
Delivery charges vary by product category and order value. Items may ship from different suppliers and arrive separately, so delivery charges can be shown per part of your order at checkout.
Standard (Nationwide) Delivery
Core Products
Core
ORDER VALUE
DELIVERY CHARGE
Under £300
ex. VAT
£30
ex. VAT
Over £300
ex. VAT
FREE
Core Delivery charges apply only when all products in an order that have equivalents are accepted as such. If even one product cannot be substituted with an equivalent, the entire order will not qualify for Core Delivery charges.
Insulation, Plasterboard and Drylining Products
ORDER VALUE
DELIVERY CHARGE
Under
£400
£45
ex. VAT
Over
£400
ex. VAT
FREE
Express Delivery
Express Delivery - Insulation and Plasterboard & Drylining
We work with a nationwide network of trusted suppliers. Items in your basket may be supplied by different suppliers and delivered separately. Where this applies, you will see delivery charges shown at checkout for each part of your order. We always aim to group products from the same supplier to keep delivery costs as low as possible.
Delivery areas
Delivery charges apply to mainland UK, excluding: AB, CA, CF, DD, DG, EH, EX, FK, KA, KW, KY, IV, LA, LD, LL, ML, NP, PA, PH, PL, SA, SY, TR, TQ and TD.
If your address is in one of these areas, we will contact you before processing your order to confirm any additional costs. We do not currently offer delivery outside the UK mainland.
What to expect on delivery day
Deliveries are typically kerbside.
Please ensure someone is on-site to accept delivery. For heavier items, help with offloading may be required.
Many building materials arrive on large vehicles. If access is restricted, a specialist vehicle such as a HIAB may be required and could incur an additional charge.
Why delivery can cost more than typical parcel delivery
Building materials often travel on larger vehicles and usually carry fewer drops per run than parcel networks. That is why delivery charges can be higher than standard e-commerce shipping.
Returns
Returns depend on what you have bought and whether there is anything wrong with it. For full details on eligibility, timeframes, and exclusions, please see our full policy.
Yes, you can easily cut GA4050 boards using a standard fine-toothed hand saw or a sharp utility knife. For the best results, use a straight edge for a clean cut and always remember to wear a dust mask and safety glasses to protect yourself from the fine dust.
Will the boards settle or lose their heat-saving performance over time?
When fitted correctly in a dry, sealed structure, these boards will maintain their thermal performance for the lifetime of the building. Just ensure all joints are taped securely with foil tape to prevent drafts and condensation.
Can I put my floor finish and heavy furniture directly on top of GA4050?
No, PIR insulation isn't designed to support heavy point loads directly. You must install a rigid, load-bearing layer (such as chipboard, plywood, or a concrete screed) over the insulation to distribute the weight safely.
Is this insulation board completely waterproof for outdoor use?
It is highly moisture-resistant but not fully waterproof, meaning it shouldn't be left exposed to the elements. If you're insulating highly damp areas, always consult a professional for proper weatherproofing advice.
Learn more
Learn more
Learn more
