25mm Kingspan Kooltherm K103 Floorboard Insulation
2.4m x 1.2m | 2.88m² per board
Delivery
We'll get your order to you fast, keeping you in the loop every step of the way.
Most stocked items reach mainland UK in just 3 working days, and many arrive sooner.
On orders over £500 ex VAT. Under that? Just £50 ex VAT, or only £35 ex VAT if you're within 35 miles of our Rotherham depot.
After ordering to confirm your delivery day. No guessing, no chasing us.
On highlighted products. Order before 12pm and we'll have it with you tomorrow.
Available on selected products. Your options and pricing are calculated automatically at checkout.
We deliver nationwide, with Moffett mechanical offload taking care of the heavy lifting.
Sometimes possible, just contact us to find out.
Deliveries are made kerbside, Monday to Friday.
Dates are an estimate, not a guarantee. We deliver to UK mainland addresses. Please contact us before ordering if your postcode starts KW, IV, AB, PH, PA, DD, KY, BT, TR, PL, EX, TQ, HS or ZE, as these may cost more, take longer, or fall outside our delivery area.
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Product Description
Product Description
25mm Kingspan Kooltherm K103 Floorboard is a rigid thermoset phenolic floor insulation board, supplied here as single sheets measuring 2.4m x 1.2m. It is the thinnest board in the K103 range, and at 25mm it is typically specified where floor depth is limited: as a thin upgrade or topping-up layer, in garage conversions, as part of a multi-layer build-up, or cut down to form the perimeter upstand strips that reduce heat loss at the floor edge.
Each sheet measures 2400mm x 1200mm and covers 2.88m². The phenolic core has a thermal conductivity of 0.019 W/mK, one of the lowest figures available in rigid floor insulation, giving the 25mm board a thermal resistance of 1.30 m²K/W. Its compressive strength of 120 kPa allows it to carry screed and normal floor loads, and it is faced on both sides with a glass tissue based facing, autohesively bonded to the core during manufacture. Because phenolic reaches a given thermal resistance in less thickness than higher-lambda materials, the 25mm board adds insulation where there is little room to spare.
The glass tissue facing keeps the board straightforward to handle and to cut cleanly, either with a fine-toothed saw or by scoring and snapping. Single sheets can therefore be trimmed accurately to fit between joists or sized into perimeter strips with minimal waste, which matters most on smaller areas and finishing work where offcuts add up.
25mm Kooltherm K103 is used in beam and dense block ground floors, suspended timber ground floors and solid concrete ground floors, installed below the screed, below the slab or between the joists depending on the construction. It should be laid over a damp proof membrane, installed in line with Kingspan's guidance and the project specification, and is not fitted directly over timber joists. It suits new build and refurbishment across domestic, commercial and industrial floors, and is compatible with underfloor heating systems.
Key Benefits of Kingspan Kooltherm K103:
- 25mm rigid thermoset phenolic floor insulation board, the thinnest board in the K103 range.
- Thermal conductivity of 0.019 W/mK, one of the lowest available for rigid floor insulation.
- Thermal resistance (R-value) of 1.30 m²K/W for the 25mm board.
- Compressive strength of 120 kPa, allowing it to carry screed and normal floor loads.
- Glass tissue facing on both sides for clean cutting and straightforward handling.
- Single sheets of 2.4m x 1.2m covering 2.88m² each, so you order the exact quantity the job needs.
- Suitable for beam and block, suspended timber and solid concrete floors, below slab or screed.
- Adds thermal performance where floor build-up height is limited, including garage conversions and topping-up layers.
- Cuts down to form the minimum 25mm perimeter upstand strips that limit cold bridging at floor edges.
- Compatible with underfloor heating systems and suited to both new build and refurbishment.
Good to know:
- Kingspan Kooltherm K103 must be installed over a damp proof membrane (minimum 1200 gauge polythene) and is not recommended in direct contact with subsoil.
- The board resists the passage of water vapour but is not a vapour control layer; below a screed it should be overlaid with a separate polythene sheet, lapped and taped, to act as the VCL.
- It is not suitable for installation directly over timber joists; in suspended floors it sits between the joists on battens, saddle clips or nails.
- At 25mm the board's 1.30 m²K/W resistance suits upgrade, top-up, multi-layer and perimeter-strip use; check the full floor build-up against your target U-value before ordering.
Buying for a whole floor? This board is also available by the pack (12 sheets, 34.56m²): view the K103 pack.
When floor depth is the constraint, the 25mm board adds thermal performance in the slimmest layer in the range, sheet by sheet.
Certifications & Standards
Certifications & Standards
Technical Datasheets
Technical Datasheets
- Kingspan Kooltherm K103 Datasheet
- Kingspan Kooltherm K103 Floorboard - Brochure
- Kingspan Kooltherm K103 Floorboard - Certificate of Constancy of Performance
- Kingspan Kooltherm K103 Floorboard - Declaration of Performance
- Kingspan Kooltherm K103 Floorboard - BBA
- Kingspan Kooltherm K103 Floorboard - Environmental Product Declaration
- Kingspan Kooltherm - Certificate of Approval
- Kingspan Kooltherm - Product Saftey Information
Customer Information
Customer Information
Free delivery on orders over £500 ex-VAT. All orders below £500 (ex-VAT) are subject to a £50 delivery charge.
Ordering & Delivery
How do I place an order with Insulation UK?
You can place an order for delivery anytime online. If you want to collect from our distribution centre in South Yorkshire then please email us your requirements at sales@insulationuk.co.uk
and we will send a payment link and collection instructions. If you can’t see what you are looking for or need more information, then call our team on 03003 034 578 and we can sort your order from there.
How do I know what’s happening with my order and when I will receive it?
When you have placed your order, you will then receive an email confirmation, giving you an order reference number and asking you to double check everything is correct on your order such as delivery address, quantities etc. If there are any amendments to be made, then please reply to your confirmation email with any details.
Once the team has processed the order you will receive an email with a BY delivery date, this is the latest date you will receive your delivery.
Your final email will be a 24/48hr notification, on the day of the delivery if you need a more accurate ETA then contact the office on 03003 034 578.
Do you offer next-day delivery?
Yes, we do on certain lines, you will see our next day delivery products marked as NEXT DAY. Order before 12pm for next day delivery (charges will apply)
How much does delivery cost and how long will it take?
Standard delivery is £50 + VAT for all orders below £500 excluding VAT, above £500 excluding VAT delivery is free. Bespoke deliveries can be made but will incur charges. Each product page gives you an estimate delivery by date. For more accurate information call the team on 03003 034 578
Can I choose a specific delivery date or time slot?
We will endeavour to try and accommodate a preferred date, if you need a delivery on a certain day, then please call us on 03003 034 578.
Do you deliver nationwide?
We deliver across most of the UK; however, some postcodes are restricted due to their location. Check out our delivery map for more information. If you find that you are in area we don’t deliver to, we have access to a wide range of haulage options, please call the team on 03003 034 578 to discuss your requirements further.
Will the driver help unload the insulation products?
Most of our deliveries are made with vehicles with mechanical off-load (known as a moffett or fork-lift), the driver will leave them in a safe place of your choice. They will help as much as they are allowed but are not insured to bring anything into a property.
What happens if my order arrives damaged or incomplete?
In the unlikely event your order arrives damaged, then please contact within 48 hours at sales@insulationuk.co.uk with any images of the damage and the team will be in touch. If there is anything missing, then notify the team within 48 hours on 03003 034 578
What if my order doesn’t arrive and I have paid for trades to be on site, can I claim anything towards the costs I have incurred?
We advise not to have trades booked in and around the day of your delivery. Things can happen beyond our control, and your delivery may be delayed or abandoned. We cannot be held liable for any consequential loss such as tradesman wages etc.
Product Advice & Support
How do I know which insulation product is right for my project?
With such a variety of insulation products, we fully understand making sure you have the right one can seem daunting. Our team have over 50 years of experience in the construction industry and there isn’t a question they haven’t been asked! Speak to our technical team on 03003 034 578 and they will be happy to offer some help and guidance.
Do you offer technical advice or support before I buy?
Yes we do! Just call 03003 034 578 and ask for our technical team and we will be happy to support you.
Product Information & Suitability
Product descriptions on this website are provided as general guidance only and are not a substitute for the manufacturer’s Technical Data Sheet (TDS), fire classification information, and the project’s design/specification requirements. Suitability depends on the full build-up and intended use (including any requirement for encapsulation, coverings, and compliance with Building Regulations and the project fire strategy).
It is the customer’s responsibility to confirm, before ordering, that the product specification and performance are suitable for the intended application by reviewing the relevant TDS and taking professional advice where required. If you are unsure, contact us before purchase and provide your intended build-up so we can confirm what information we can support.
Nothing in this notice limits or excludes your statutory rights
Can I speak to someone to confirm product specifications?
Of course you can! There is also a range of data sheets and guides available on the product pages under Technical Information.
Are your products suitable for both DIY and trade customers?
Yes, they are. If you are new to DIY projects involving insulation,
then we advise to always do your research. We have a handy guides section which may help.
Do you offer fire-rated or eco-friendly insulation options?
Yes, we do. Fire ratings are indicated in the specification table on the product page, and our sustainable range is continually growing.
Pricing & Payments
Do you offer trade or bulk-buy discounts?
We always aim to offer the best price online; however we do offer project pricing for larger orders, speak to our sales team with your requirements on 03003 034 578.
What payment methods do you accept?
We accept all major cards including American Express, as well as Apple Pay, Google Pay and PayPal
Can I set up a trade account with credit terms?
We do offer trade accounts, however there are certain criteria we ask for, and any credit account application is subject to credit checks. Call the team on 03003 034 578 to discuss any credit applications.
Do your prices include VAT?
The website has a toggle at the top right of the page so the prices can be displayed including and excluding VAT. VAT, where applicable, is charged at checkout.
Returns & Cancellations
Can I return unwanted insulation products?
Contact the team via email sales@insulationuk.co.uk with the items you wish to return and any other information. Please note if we you need us to collect any unwanted items,
a collection fee will apply.
How do I arrange a return or exchange?
Contact the team via email sales@insulationuk.co.uk or check out our refund policy.
Are there any restocking fees?
Restocking charges will apply in certain instances, please contact the team via email at sales@insulationuk.co.uk check out our refund policy.
What if I’ve ordered incorrectly or need to cancel my order?
Contact the team via email as soon as possible. The best way to get in contact is to reply to any of the emails we have sent you, they will come straight through to the team and will have any relevant order information already on there.
Installation & Compliance
Do you offer installation services or just supply materials?
We do not offer any installation services; we are a supplier of insulation and building materials.
Can I get a datasheet or certificate of performance for your products?
Yes, data sheets can be found in the Technical Information drop down on the product page.
How should I store insulation products before installation?
There are a variety of insulation products each with their own storage instructions. Generally, please keep them off the ground, in a dry area, away from the elements.
Sustainability & Quality
Are your insulation products environmentally friendly?
This depends on the individual products, data sheets are available,
and any environmental benefits are noted on the product pages.
Do your products help reduce energy bills?
The correct insulation properly installed can reduce heat loss from a building and therefore help reduce energy costs.
Are your products made in the UK or imported?
With such a wide variety of products some are made in the UK and some are imported.
Customer Service & Support
How can I contact your support team?
By phone on 03003 034 578, email sales@insulationuk.co.uk or via our
webchat online
What are your opening hours?
Monday to Friday 8am to 5pm for sales and technical support, orders can be placed on line 24/7
How quickly can I expect a reply to my enquiry?
We aim to respond to our customers as quickly as possible.
Technical Details
- Brand:
- Kingspan
- Material:
- Phenolic
- Manufacturers Part Number:
- 100000032305
- Length:
- 2400 mm
- Width:
- 1200 mm
- Thickness:
- 25 mm
- Unit Coverage:
- 2.88 m²
- Sqm Per Pack:
- 34.56 m²
- Applications:
- Walls, Floors, Roof
- Edge Type:
- Square
Thermal performance helps show how effectively the product reduces heat transfer.
Thermal conductivity measures how readily heat passes through the material, so lower figures generally indicate better insulating performance.
R Value shows the material’s thermal resistance at that thickness, so higher figures generally mean stronger insulation performance.
These figures relate to the insulation product itself and should be considered alongside the full wall, roof or floor build-up when checking project requirements.
- Thermal Conductivity:
- 0.019 W/mK
- R Value:
- 1.30 m²K/W
Compressive strength shows how well a product resists being squashed under pressure.
The figure is measured in kPa, which stands for kilopascals.
A higher kPa number means stronger resistance to compression. For example, 120 kPa offers more compression resistance than 70 kPa, but less than 150 kPa, 200 kPa or 300 kPa.
This does not mean the product can carry that load on its own. It should always be checked as part of the full floor, wall, roof or system build-up.
- Compressive Strength:
- 120 kPa
Euroclass reaction to fire is the European EN 13501-1 classification used to show how a construction product behaves when exposed to fire.
The main scale runs from A1 and A2 at the highest end, through B, C, D and E, down to F.
A1 is non-combustible and A2 is limited combustibility, while lower classes indicate a greater contribution to fire.
Euroclass F is the lowest rating on this scale and indicates the weakest reaction-to-fire performance.
This is different from fire resistance, which relates to how long a complete wall, floor or roof build-up can resist fire.
- Reaction to Fire:
- Euroclass C-s2,d0
