Product Filters

  • Manufacturer

  • Material type

  • Thermal conductivity

  • Width

  • Thickness

  • Compressive strength

Clear all

Floor Insulation Boards

(138 Products)

Reducing heat loss starts with improving a property's thermal envelope. Whether you need to insulate between floor timber joists or you are looking for underfloor heating insulation boards, we've got you covered. We stock a range of thermally efficient floor insulation boards for different existing or new floor applications. Choose from a range of boards from leading brands like Celotex and Kingspan between 20mm and 150mm thick.

Find Out More About Our Types of Floor Insulation Board
Filter Products

What are Floor Insulation Boards?

Did you know that at least 10% of household heat is lost through the floor? Floor insulation boards are a must when creating a complete seal around a building. 

Not only do they do an excellent job of reducing the U Value of your floor in line with current building regulations but they also work behind the scenes to improve the heat retention of a property.

Whether you're looking to insulate solid ground floors, suspended floors, heavy-duty floors or soffits, floor insulation boards are a comprehensive solution to sealing off gaps between floors and skirting boards. 

A property that is sealed off from the elements will maintain a temperature-controlled interior - meaning cooler summers and warmer winters which, luckily for you, goes hand in hand with lower energy bills. 

What's more, floor insulation boards are just as convenient as they are thermally efficient. Rigid yet lightweight in their composition, floor insulation panels can be cut into different shapes with ease.  

Whether you're looking for high compressive strength or precision cut tongue and groove joints, there's a floor insulation board for every job. 

Floor Insulation Board Types

We sell a range of the most popular floor insulation boards available on the market.  

When it comes to insulating floors, our customers tend to lean towards boards as they are easier to handle and install than other popular floor insulants such as insulating screed and polyurethane spray.

When choosing the right insulation board, our customers can choose from a range of materials. Follow this guide to find out which material best suits your insulation needs.

  • PIR - Polyisocyanurate (PIR) is equipped with a few simple properties that make it an excellent choice for a range of insulation needs; it has a closed-cell structure (and is water-resistant thanks to this), is extremely lightweight, and also rigid. With a thermal conductivity of just 0.022 W/mK, PIR boards are highly thermally efficient, offering affordability, availability and thermal performance in one robust material.
  • Phenolic - Phenolic floor insulation boards are the holy grail of thermal insulation boards. They have over 90% closed-cell formation and deliver unparalleled protection against heat loss with minimal thickness. Offering water-resistance, fire retarded properties and thermal conductivity values as low as 0.018 W/mK, phenolic insulation is the highest performing insulant on the market.
  • EPS - Expanded polystyrene (EPS) is the least thermally efficient insulation solution with a thermal conductivity of 0.038 W/mK. Despite its performative inferiority to more premium brands of thermal insulation, EPS exhibits consistent thermal performance in an extensive range of building insulation applications. Not only does it possess high load-bearing capacity but it is also moisture resistant and unaffected by bacteria, moulds and fungi.
  • XPS - Extruded polystyrene insulation XPS is manufactured, as the name would suggest, through an extrusion process. Kingspan is the main manufacturer of this insulation in the UK. The closed-cell structure of extruded polystyrene (XPS) prevents water penetration, thus acquitting the need for a vapour control layer. Kingspan GreenGuard boards have a thermal conductivity of 0.034 W/mK. As such, XPS foam is marginally more effective than EPS foam as a thermal insulator.  


We stock Kooltherm K103 Floorboard a premium floor insulation board with a thermal conductivity of just 0.018 W/mK. These Kingspan boards should be used where ultimate thermal protection is required. If it's fire resistance you're after take a look at our Rockwool Insulation page. 

Flooring Applications That Benefit From Floor Insulation Boards

  • Underfloor Heating Systems: Floor insulation boards are commonly used in conjunction with underfloor heating systems. They not only minimise heat loss but also help to distribute the heat evenly across the floor surface, optimising the system's efficiency.
  • Floating Floors: When installing floating floors, such as laminate or engineered wood, insulation boards can be placed beneath to provide thermal insulation and reduce noise transmission between floors.
  • Concrete Floor Insulation: In concrete flooring, insulation boards placed beneath the concrete slab enhance both energy efficiency and structural stability. This method is particularly effective in commercial and industrial settings.
  • Suspended Floors: Insulation boards can be used between floor joists in suspended floors. This helps maintain a consistent indoor temperature and prevents heat loss through the floor.
  • Loft Conversions: For converting attics or lofts into livable spaces, floor insulation boards are vital. They offer a cost-effective way to insulate the floor, keeping the space comfortable year-round.


Laying Floor Insulation Boards

Installing floor insulation boards does not have to be difficult. Follow these floor insulation board installation tips for your project.

Please note when laying insulation you may need other building materials such as a damp-proof membrane.

Prepare the floorboards - Clear any debris and dust away. You might have to use a layer of plywood to ensure the floor level is flat.

Prime solid floor - You need to prime a concrete floor before you lay insulation boards. Thermal primers can help to further reduce the loss of heat from your home. If you are laying insulation under timber floors, you do not have to worry about primer. You can also lay a damp proof membrane below or above the floor.

Cut the boards - You can cut floor insulation boards with a standard utility knife. We recommend marking your measurements on the board before cutting to avoid mistakes.

Place the boards - You should stagger insulation boards to reduce drafts. If you are laying solid floor insulation, use an adhesive to secure them in place. For a suspended timber floor, we recommend screwing the boards into place at 300mm intervals across the floor space. It's important not to block air bricks.

Seal the joints - You need to make sure that the seams between the joints are sealed. Lots of people use waterproof tape to seal the joints. Some people go the extra mile and use acrylic sealant before the tape.

You should always consult a professional for non-standard insulation projects.


Floor Insulation Board Thicknesses

We stock boards that range from 20mm to 150mm. 

If you purchase a thicker insulation board, you can increase the thermal value of the build-up of products. However, due to space restrictions, you may have to opt for a thinner board.

With our wide range of floor insulation thicknesses, you can always find an effective board that fits your space. 

  • Kingspan Kooltherm K103 - 25mm 150mm
  • Kingspan Thermafloor TF70  - 20mm140mm
  • Recticel Eurothane Insulation Boards - 25mm150mm
  • EcoTherm Eco-Versal PIR Insulation Board - 25mm - 150mm
  • Celotex GA4000 PIR Insulation Board - 50mm - 100mm
  • Celotex TB4000 PIR Insulation Board - 25mm - 40mm
  • Celotex XR4100 PIR Insulation Board - 110mm - 150mm

Frequently Asked Floor Insulation Board Questions

How do Floor Insulation Boards Work?

By installing underfloor insulation, you create a barrier between a property and the cold ground it sits upon, making it harder for heat to escape.

Floor insulation boards are an effective way to insulate any project; they work by trapping heat in the floor, which then radiates back into the property itself, ensuring a regulated temperature is maintained year-round.

Underfloor insulation is purposed for use in properties with suspended floors or structures with a cavity underneath. Suspended timber floors (wooden floors) are most commonly found in older properties (pre-1970s). If you have air bricks or ventilation bricks on any external wall of your property, it's likely it has a suspended timber floor.

The best way to ensure an airtight finish when insulating a suspended wooden floor is to retrofit insulation board beneath the floorboards, between the supporting floor joists. Newer homes tend to have concrete ground floors upon which insulation boards can be placed. 

Can I Install Floor Insulation Boards Myself?

Yes, many types of floor insulation boards are designed for DIY installation. However, it's important to follow manufacturer guidelines and ensure proper installation for optimal performance.


Are There Any Specific Considerations for Underfloor Heating Systems?

When using floor insulation boards with underfloor heating, it's crucial to choose boards with appropriate thermal conductivity to ensure efficient heat distribution. Consult with experts or the manufacturer for suitable options. 

Do Floor Insulation Boards Have Any Fire-Resistant Properties?

Many floor insulation boards have fire-retardant properties, but the level of resistance varies. Always choose boards that meet relevant fire safety standards for your specific application.


Are Floor Insulation Boards Worth It?

Insulation costs can seem daunting, whether they're for new build or refurbishment projects. You can recover the initial investment in anywhere from three to five years depending on the overall thermal conductivity of the materials you use.

We recommend underfloor insulation boards for people who can afford to invest in their properties long term. 

Despite there being an initial recovery period, you will see the benefits of your new insulation almost immediately. You can save around 10% on your heating bills all year round when you install underfloor rigid insulation boards.

You can purchase insulation boards for loft floors, laminate or wooden floors, solid floors and solid concrete floors.

Do Floor Insulation Boards Require Maintenance?

Floor insulation boards are generally low-maintenance. Regular checks for damage or moisture accumulation are recommended, but they do not require frequent maintenance once installed correctly.

Remember that specific information and guidelines may vary based on the type of insulation boards and the manufacturer, so it's always advisable to refer to the product's documentation and seek professional advice when necessary.

Related Articles

How To Insulate A Garage

Insulating A House: Where, How & Why?

How To Install Celotex Insulation Boards

Difference Between XPS and EPS Insulation

Insulation Installation Safety Precautions

Insulation Installation Equipment - What Do I Need?

Insulation Material Types and Their Uses

Celotex Floor Insulation Guide

Celotex vs Kingspan: What’s the Difference?

All Categories

Services