Condensation is the most common damp issue that many of us in the UK face. You see it as water droplets on bedroom windows in the morning, damp patches on cold walls, or mould creeping into loft spaces. It might not look serious at first, but if you leave it, you will soon be dealing with damaged plaster, weakened timber, and even possible health issues.
Condensation happens when warm, moist air inside your house hits a cold surface. The air cools down, can’t hold as much moisture, and releases it as water droplets. The best way to solve this problem is by using an insulation board. It keeps walls, floors, and roofs warmer, so moisture has no cold surfaces to settle on.
That said, not all insulation boards can guarantee a solution to your condensation issues. As you may know, finding the best ones requires extensive research and comparison, which can be time-consuming and tiring, especially if you’re on a busy schedule. But don’t worry, our dear reader.
We’ve done the hard work for you and picked the 10 best insulation boards for stopping condensation in UK homes. Whether you need something for a loft, a damp-prone floor, or outside walls exposed to the weather, you’ll find the best choices here, along with what each one does well and where it has limits.
Disclosure: Some of the links in this guide are affiliate links. If you buy through them, we may earn a small commission at no extra cost to you. This helps keep our guides free and up to date, but it doesn’t affect which products we recommend
10 Best Insulation Boards to Stop Condensation
1. Buildershop (UK) Ltd 2400 x 1200 x 50mm PIR Insulation Boards – Pack of 10
Best for: Loft conversions, large floor areas, or full-room insulation where you need wide coverage.
A pack of 10 PIR insulation boards (2400 x 1200 x 50mm) gives you nearly 29m² of reliable coverage, making it a practical choice for roofs, walls, or floors that need a thermal boost. Each rigid board has foil facings that reflect heat into the room, helping cut energy loss without taking up much space.
They’re lightweight, easy to handle, and simple to trim with a standard handsaw, so fitting them around joists or rafters is straightforward. Depending on your location, you’ll receive Celotex, Kingspan, or Ecotherm — three of the most trusted names in insulation boards.
Key Features
- Rigid PIR boards with foil facings for extra heat reflection
- 50mm thickness balances insulation with space saving
- Nearly 29m² of coverage per pack — ideal for bigger projects
- Easy to cut and fit around rafters, joists, or awkward gaps
- Supplied as Celotex, Kingspan, or Ecotherm, depending on stock
Pros
- Covers large areas in one go
- Trusted manufacturers (Celotex, Kingspan, Ecotherm)
- Foil facings improve thermal efficiency
- Easy to cut with standard tools
Cons
- A bulk order may be more than you need for smaller jobs
- Delivery costs can be higher in some regions
Why We Recommend Buildershop (UK) Ltd PIR Insulation Boards
This pack is perfect if you’re insulating a loft, a large floor, or multiple walls at once. The boards perform well, they’re easy to fit, and you’re getting them from brands that professionals trust. If you want a reliable way to stop condensation and make your home more energy-efficient, this is a safe bet.
Check prices on Amazon: Buildershop (UK) Ltd PIR Insulation Boards – Pack of 10
2. Generic 25mm PIR Insulation Board, 400mm x 1200mm, Pack of 6
Best for: Small jobs like topping up insulation in a couple of rooms, or tackling a chilly loft corner.
The Generic 25mm PIR insulation board (made by Recticel) is a handy option when you don’t need huge sheets but still want solid performance. Each pack covers just under 3m², so it’s well-suited to smaller projects or spot-fixes where condensation is a problem.
The boards are lightweight, easy to carry up into a loft or across a floor, and their moisture-resistant design means they hold up well even in damp-prone areas. Think of it as a no-nonsense way to add thermal insulation without blowing the budget.
Key Features
- Rigid PIR insulation that helps cut heat loss and condensation
- Compact 400mm x 1200mm size makes it easier to lift and fit
- Closed-cell core resists damp and moisture ingress
- Suitable for floors, walls, and loft spaces in both new and older homes
- Pack of six covers 2.88m² — just right for small-scale projects
Pros
- Made by Recticel, a trusted insulation manufacturer
- Moisture-resistant, so it’s reliable in damp areas
- Easy to cut and handle for DIY jobs
- Affordable way to add extra insulation where it’s needed most
Cons
- At 25mm, it’s not thick enough for major upgrades on its own
- Coverage per pack is quite limited for larger spaces
Why We Recommend Generic 25mm PIR Insulation Board
If you’ve got one or two problem rooms where condensation keeps coming back, this pack is a smart place to start. It’s simple, practical, and doesn’t demand a big budget. We like it because it gets the job done without fuss — a good choice when you want reliable insulation boards for smaller projects.
Check prices on Amazon: Generic 25mm PIR Insulation Board, 400mm x 1200mm, Pack of 6
3. Floordirekt Cork Roll Board – Natural Cork Insulation & Underlay (6mm, 100 x 200 cm)
Best for: Eco-conscious homeowners who want a versatile insulation that also doubles as a soundproofing and underlay solution.
If you’re looking for an insulation material that’s practical, sustainable, and easy to live with, cork is hard to beat. This natural roll from Floordirekt is 6mm thick and sized at 100 x 200 cm, giving you plenty of flexibility. It works just as well beneath flooring as it does on walls, and can even be used as a decorative notice board.
Naturally water-repellent, sound-absorbing, and thermally insulating, cork also brings a warm, organic finish to any room. Installation is simple—just cut it to size with a craft knife. Being renewable, recyclable, and free from formaldehyde, it’s also a safe, eco-friendly choice.
Key Features
- 100% natural cork — renewable, recyclable, and eco-conscious
- Provides both sound and heat insulation
- Suitable as floor underlay, wall covering, or protection board
- 6mm thickness (other options from 2–8mm available)
- Easy to trim and fit with a standard craft knife
Pros
- Sustainable and environmentally friendly
- Multipurpose use across the home
- Lightweight and simple to install
- Naturally water-repellent and shock-absorbent
Cons
- Not as thermally efficient as thicker PIR or foil-backed boards
- May compress slightly under heavy furniture
Why We Recommend It
Floordirekt’s cork roll is a great pick if you want insulation that’s practical without compromising on sustainability. It’s comfortable underfoot, reduces noise, and helps retain warmth, all while being easy to handle and install. While it won’t match the insulation power of PIR boards in harsher climates, it’s an excellent underlay and multipurpose solution for everyday use.
Check prices on Amazon: Floordirekt Cork Roll Board – Natural Cork Insulation & Underlay
4. ProWarm 10mm XP-Pro Premium Insulation Board (1200 x 600mm)
Best for: Homeowners and installers wanting reliable, affordable insulation for underfloor heating.
If you’re adding underfloor heating to a concrete or screeded floor, ProWarm’s XP-Pro boards are designed for the job. Each 1200 x 600mm board is made from tough extruded polystyrene (XPS), which keeps the heat moving upwards into your room instead of disappearing into the subfloor.
Don’t be fooled by how light they feel — these slim 10mm boards can handle serious weight, tested to 30 tonnes per m². That means they’ll stay solid under flooring, furniture, and everyday use. The low profile is also handy if you don’t want to raise your floor height too much. Fitting them is simple: lay the boards in a brick-bond pattern, place your heating mats on top, and you’re good to go.
Key Features
- 10mm thick extruded polystyrene board (1200 x 600mm)
- Designed for underfloor heating insulation
- Strong load capacity (30 tonnes per m²)
- Lightweight and easy to cut or carry
- Cost-effective way to improve energy efficiency
Pros
- Great thermal performance under heating systems
- Slim design — perfect where floor build-up is an issue
- Handles heavy loads without compressing
- Quick and easy to install
Cons
- Too thin for walls, roofs, or general insulation jobs
- Works best only when paired with heating mats
Why We Recommend It
If you’re fitting underfloor heating, these boards are a smart upgrade. They’re tough, easy to fit, and help keep running costs down by reducing heat loss. They’re not meant to replace thicker wall or roof insulation, but for heating projects, they’re reliable, practical, and well-priced.
Check prices on Amazon: ProWarm 10mm XP-Pro Premium Insulation Board
5. Triplast EPS 70 Insulation Foam Sheets (10 Pack, 600 x 400 x 25mm)
Best for: DIYers, homeowners, and small businesses looking for insulation that also doubles up as packaging or craft material.
If you want something affordable that still does the job properly, Triplast’s EPS 70 foam sheets are a solid choice. At 25mm thick, they’re light enough to handle easily yet strong enough to boost thermal efficiency in walls, floors, or even a garden shed. Being EPS 70 grade and BBA-certified means they’ve been tested to UK standards, unlike generic polystyrene sheets.
The real advantage is versatility: line a small space, protect fragile deliveries, or cut them for school or craft projects. Non-toxic and easy to trim, they’re a practical multipurpose material that won’t crumble like cheaper alternatives.
Key Features
- Pack of 10 sheets (600 x 400 x 25mm) — easy to carry and store
- EPS 70 grade, BBA-certified — tested to UK insulation standards
- Low thermal conductivity (0.030–0.038 W/mK) — helps keep heat in
- Damp-proof, odourless, rot-resistant — lasts well over time
- Recyclable, zero GWP, A+ BRE Green Guide — more eco-friendly choice
Pros
- Affordable insulation for small jobs
- Doubles up as packaging or craft boards
- Easy to cut, sand, or shape
- Better for the environment than many alternatives
Cons
- Flammable (Euroclass F) — must be handled safely indoors
- Plain white boards with the odd black speck
Why We Recommend Triplast EPS 70
This is one of those “handy to have around” products. You can insulate a shed wall, protect a fragile mirror during a house move, or let the kids build a school project — all with the same pack. Sure, they’re not a replacement for foil-backed or thicker PIR boards on a main wall, but for versatility at a low cost, they punch well above their weight.
Check prices on Amazon: Triplast EPS 70 Insulation Foam Sheets
6. Jablite 25mm Multi-Purpose Insulation Boards (12 Pack)
Best for: homeowners, builders, and renovators who want reliable insulation for floors, walls, roofs, or underfloor heating.
When you’re choosing insulation, it’s easy to get lost in technical jargon. But here’s where Jablite stands out. First, these HP boards use expanded polystyrene enhanced with carbon. That small detail matters, because it doesn’t just insulate — it actively reflects and disperses heat for noticeably better performance.
Then, there’s the practicality. Each board feels lightweight yet sturdy, so you can cut and fit them without a struggle. And because they resist moisture and freeze-thaw damage, you don’t have to worry about them failing over time. In short, once installed, they’ll keep doing their job for the life of the building. That’s the kind of reliability most people nod along to.
Key Features
- 12 boards (120 x 45 x 2.5 cm each), covering 5.81 sq. ft.
- Carbon-enhanced EPS for higher thermal efficiency
- BBA certified, meeting BS EN 13163 standards
- Moisture and freeze-thaw resistant
- Works with underfloor heating, cavity walls, timber, floors, and roofs
Pros
- Strong insulation across multiple uses
- Easy to handle and cut cleanly
- Lightweight yet durable
- Long-lasting performance you can count on
Cons
- Needs fire protection in exposed areas
- At 25mm thick, not the best if you’re chasing very low U-values
Why We Recommend Jablite
All things considered, Jablite HP is more than just a budget insulation board. It combines efficiency, durability, and versatility in one package, making it an easy choice for DIYers and professionals alike. Whether you’re upgrading a loft, laying underfloor heating, or tackling cavity walls, these boards give you solid performance without overspending. In other words, it’s the kind of product you’ll feel good about using.
Check price on Amazon: Jablite 25mm Multi Purpose Insulation Boards Floor Wall Roof & Underfloor Heating (12)
7. BXI Ceramic Fiber Thermal Insulation Board (1500°C) – 30x20x1cm
Best for: blacksmiths, glass blowers, kiln users, and anyone dealing with extreme heat.
Product Description
Not all insulation can handle fire, but this board shrugs it off up to 1500°C. It’s made from high-density aluminosilicate ceramic fiber, giving it strength, rigidity, and long-term durability. It resists flames, chemicals, and thermal shock, so it performs just as well in a forge as in a pottery kiln.
And because it’s inorganic, you won’t get the smoke or smell that cheaper boards give off. In short, if you work with high temperatures, this is a board you can rely on without second-guessing.
Key Features
- Size: 30 x 20 x 1cm, weight 0.31kg
- Density: 600kg/m³ for superior rigidity
- Fire resistant (Class A1), max use temp 1500°C
- Low thermal conductivity: 0.082W/mK
- Cuts easily with a saw or knife
Pros
- Handles extreme heat without breaking down
- Strong and durable structure
- Safer than organic boards (no smoke or odour)
- Useful for forges, kilns, ovens, and stoves
Cons
- Limited coverage per board
- Not suitable for food-related use
Why We Recommend BXI
This board isn’t about general home insulation — it’s built for fire. Whether you’re lining a forge, shielding a kiln, or creating a heat barrier in a workshop, it won’t let you down. It cuts easily, stays solid under pressure, and gives you peace of mind when working with extreme heat.
Check price on Amazon: BXI Ceramic Fiber Thermal Insulation Board(1500°C) – 30cmx20cm, Thickness: 1cm, Pack of 1
8. Cosyspace XPS Foam Insulation Boards (1200 x 600 x 10mm, Pack of 10)
Best for: Underfloor heating systems and as thermal underlay for laminate, tile, and wood flooring.
Cosyspace’s XPS boards are rigid foam sheets made through extrusion, which gives them a dense, closed-cell structure. This design makes them both water-resistant and thermally efficient. At just 10mm thick, they don’t raise floor levels much, but they still provide a reliable barrier that prevents heat loss into the subfloor. This makes them a strong partner for both electric and water underfloor heating systems.
Each board measures 1200 x 600mm, covering a decent area while staying light and easy to handle. The boards also reduce impact noise, making them useful as an underlay beneath laminate or solid wood flooring. Their resistance to compression and ageing means they won’t crumble or lose effectiveness over time, even in damp or humid spaces like kitchens or wet rooms.
Key Features
- Pack of 10 boards (1200 x 600 x 10mm each)
- XPS (extruded polystyrene) with a closed-cell structure
- Water-resistant and resistant to compression
- Provides thermal and acoustic insulation
- Lightweight, recyclable, and simple to cut to size
Pros
- Excellent thermal layer for underfloor heating systems
- Thin profile avoids raising floor levels too much
- Works as both insulation and soundproofing underlay
- Water-resistant and suitable for humid rooms
Cons
- At 10mm, the insulation depth is limited compared with thicker XPS options
- Not fire-rated — must be protected with suitable floor finishes
Why We Recommend Cosyspace XPS Boards
These boards are a practical, no-fuss way to boost the efficiency of underfloor heating and prevent heat loss through floors. Their strength, water resistance, and soundproofing ability make them useful beyond heating projects, whether you’re insulating a wet room, levelling a floor, or just cutting noise under hard flooring. They’re lightweight, versatile, and easy to fit, which makes them a smart choice for both homeowners and trade users.
Check prices on Amazon: Cosyspace XPS Foam Insulation Boards
9. Thermopanel Tile Backer Board Insulation Sheets (800 x 600 x 6mm)
Best for: Bathrooms, wetrooms, and underfloor heating projects.
If you’re laying electric underfloor heating or tiling a wet area, these boards make the job both easier and safer. At just 6mm thick, they hardly raise floor levels, yet they still provide solid insulation under heating mats and cables. On top of that, they’re fully waterproof, so you don’t need to worry about leaks in bathrooms or wetrooms.
Unlike plasterboard, which can sag under weight, these boards support heavy wall tiles with no problem—as long as they’re fitted properly. They cut cleanly, handle well, and give you a base that feels reliable right from the start.
Key Features
- Size: 800 x 600 x 6mm (covers 5.17 sq ft)
- Foam core with reinforced layers
- Waterproof and suitable for wet areas
- Strong enough for heavy tiles when installed properly
- Lightweight and easy to cut
Pros
- Adds insulation under heating mats and tiles
- Creates a waterproof layer in wetrooms
- Slim profile that saves space
- Stronger than plasterboard for tiled walls
Cons
- Thin boards mean limited insulation depth
- Needs proper installation to handle heavy loads
Why We Recommend Thermopanel Boards
Thermopanel boards bring three benefits together—insulation, waterproofing, and strength—without adding bulk. That makes them especially useful in bathrooms and wetrooms, where you want to keep heat in and damp out. They’re also much easier to cut and fit than traditional backer boards, so you can move faster without losing reliability. In short, they give you a practical, space-saving solution that holds up over time.
Check prices on Amazon: Thermopanel Tile Backer Board Insulation Sheets (800 x 600mm)
10. FloorPro XPS Foam Underlay – 5mm Boards for Laminate & Wood Flooring
When you’re laying a new floor, the underlay is what makes the difference between a job that just looks good and one that feels good every time you walk on it. The FloorPro XPS Foam Underlay is designed for wood and laminate flooring, giving you a stable base that also tackles two common headaches: cold creeping up from the subfloor and that hollow “clack” noise when you walk across the room. At 5mm thick, these boards smooth out minor uneven spots, insulate against heat loss, and cut down sound — all without adding unnecessary bulk.
Key Features
- Made for wood & laminate: Works under both, so you don’t need separate products.
- Good coverage: One pack = 21 boards (590mm x 790mm), covering 9.79m².
- Warm & quiet: Up to 2.2 TOG thermal insulation + around 23dB sound reduction.
- Levels the floor: Deals with small bumps and dips for a smoother finish.
- DIY-friendly: Lightweight boards are easy to cut and fit; just use Barrier Pro X Tape to join them.
Pros
- Strong thermal insulation keeps rooms warmer
- Noticeable sound reduction under wood or laminate
- Levels uneven subfloors without fuss
- Easy to cut, lift, and install
- Versatile for most home flooring projects
Cons
- Only 5mm thick, so not the deepest insulation layer
- Requires joining tape for a secure fit (extra cost)
Why We Recommend FloorPro XPS Underlay
This underlay makes your new floor feel solid, warm, and quiet — all the things you want once the surface goes down. It’s straightforward to install, fixes small imperfections, and adds real comfort underfoot. For the price, it’s a practical upgrade that improves the look, feel, and lifespan of your flooring project.
Check prices on Amazon: FloorPro XPS Foam Underlay 5mm Boards
Buying Guide: Best Insulation Boards to Stop Condensation
1. Know Why Condensation Forms
Condensation starts when warm indoor air meets a cold surface such as a wall, floor, or ceiling. The air cools quickly, releasing water droplets that settle on the surface. Over time, this creates damp patches, peeling paint, and eventually mould growth. Insulation boards work by raising the surface temperature, so moisture has no cold spot to cling to.
2. Choose the Right Type of Board
Not all insulation boards are the same, and the right choice depends on where you’re using them.
- PIR Boards (Celotex, Kingspan): High performance in slim sheets, perfect for walls where space matters.
- XPS Foam Boards: Lightweight, moisture-resistant, and often used under floors.
- Tile Backer Boards: Waterproof and tough, making them ideal for bathrooms and wetrooms.
- Cork Boards: A natural, breathable option that resists mould while being eco-friendly.
3. Match the Board to Your Project
Think about the room before you choose. Bathrooms and wet areas benefit from tile backer boards. Bedrooms or living spaces often pair well with XPS foam underlays beneath flooring. For external walls, PIR boards give strong thermal efficiency without taking up much space. If sustainability matters to you, cork offers a natural and breathable solution.
4. Check the Key Features
A good insulation board should deliver on three essentials:
- Thermal resistance – keeps surfaces warm and prevents condensation.
- Moisture protection – reduces damp build-up and mould risk.
- Practical thickness – balances insulation with usable room space.
5. Install It Properly
Even the best board won’t work if poorly installed. Always seal the joints, secure the boards firmly, and prepare clean, dry surfaces before fitting. Proper installation ensures the boards perform at their best and last longer.
Final Thought
When choosing the best insulation board for stopping condensation don’t focus only on cost. Spending a little more on the right board often saves you from expensive repairs later. Match the board to the room, install it carefully, and you’ll see a noticeable reduction in condensation from day one.
