Floor Insulation Boards

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.

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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.  

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.

●     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. 

●     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.

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. 

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. 

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.

How to Lay 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.