What is the Best Material For Loft Insulation?

Insulation, Membranes & Felts
product guide
man installing pink loft insulation between joists

Choosing the right loft insulation is an incredibly important task. Did you know that a home without adequate insulation can lose a quarter of its heat just through the roof? That’s a huge amount of avoidable heat loss that really takes a significant toll on your energy and heating costs over the years!

Investing in a good-quality insulation for your loft space is a fundamental way of enjoying more comfortable living temperatures and keeping those bills to a minimum. In fact, according to energysavingtrust.org.uk, the right insulation (when installed correctly) can pay for itself multiple times over its total lifespan – a truly worthy investment!

So, the big question is – which loft insulation is best to buy? Well, the simple answer is that depends on what you mean by ‘best’! In this, article, we’ll talk you through each of the different loft insulations available on the market and give you an insight into which may be the most right option for your loft space.

Different Types of Loft Insulation

Blanket Insulation

Produced in the form of batts and rolls, blanket insulation is the most popular and widely obtainable insulation product currently on the market. It is available in a range of different materials including fibreglass/glass wool as well as mineral wool, plastic fibres and natural fibres such as sheep’s wool.

The ideal choice for DIYers, blanket insulation is brilliantly easy to install and generally very affordable. It’s a great all-purpose insulation, especially for between joists or exposed wall cavities. Whilst blanket rolls can be too bulky to fit in tight spots or around obstructions, they are perfect if you have a wide attic space with a large floor span to cover. You can even buy the rolls pre-cut in different thicknesses so there’s no need to waste time cutting and measuring yourself.

Insulation Boards

Insulation boards are a rigid insulating material manufactured in sheet form using either synthetic or natural substances. Whilst there are a practical range of sizes and thicknesses to choose from, the boards can be easily cut to size using a handsaw or similar to accommodate any specific space you have to fill.

Although slightly pricier than blanket rolls, rigid boards offer exceptional insulating value at half the thickness! They are ideal for use in large attic spaces and loft conversions, insulating both joists and rafters with top thermal efficiency. You can even safely store items directly on top of the boards, so won’t have to compromise vital storage space. 


Multifoil insulation is made by comprising multiple layers of radiant foil barriers crafted using materials such as aluminium, thermo-foam and polypropylene. The combination of foils work by reflecting heat back into the room to retain comfortable internal temperatures throughout both winter and summer.

Thanks to its thin and lightweight structure, multi-foil insulation is very space-efficient and easy to install wherever you need it. All you have to do is simply staple the foil to the rafters and tape over any joins to finish. Pretty easy, right? Better yet, multi-foil is also airtight and moisture resistant with built-in vapour control so provides an additional method of preventing damp and condensation from occurring.

Insulation Slabs

Commonly made from glass wool, mineral wool or even sheep’s wool, insulation slabs (also known as insulation batts) offer superb thermal and acoustic insulation for your roof space.

An increasingly popular choice amongst homeowners and DIYers, insulation slabs are very straightforward to cut and fit into place. They can be easily pushed in between joists and rafters to create the perfect friction fit plus come in a practical array of specific sizes so can often be fitted straight away without cutting.

Loose-Fill & Blown-In

Used as top-up materials or simply on their own, loose-fill and blown-in insulations are comprised of lightweight, loose fibres that are spread freely into place. Cellulose, fibreglass and rock wool fibres are typically blown into position by professional installers whilst less common materials such as polystyrene beads and perlite are poured.

The fundamental advantage of loose-fill is that it can be installed in hard-to-reach areas where alternative insulation types would be a tricky fit. The material is also often cheaper to buy and can contain up to 75% recycled content so is an eco-conscious choice for those looking to go greener.

The main down-side of loose insulation is the fitting process itself. Installation can get very messy and requires the help of a trained expert in order to achieve the best possible results. It also doesn’t create an airtight seal so can drift and settle in different areas, leading to unsecure and uneven coverage.

Sprayed Foam

As implied in the name, spray foam insulation is sprayed into place and then forms an insulating layer once set. There are two types of spray insulation available: closed cell and open cell.

The unique nature of spray foam means that once applied to cracks, it expands and dries quickly, blocking air and water from the internal wall whilst also trapping hot and cold air. This not only enhances thermal and acoustic insulation, but also helps to prevent rising damp, block pests, and even reduce the entry of allergens!

It is important to note that sprayed foam can emit harmful fumes and even cause structural damage when applied incorrectly so it is always recommended that only a professional contractor install it.

Acoustic Insulation

Thanks to its high density structure and clever use of materials, acoustic insulation is ideal for creating a quieter home free from noisy neighbours and stomping footsteps overhead. By easily installing acoustic insulation slabs in your loft space or conversion, you can block both impact and airborne sound transmission through the walls, floor and roof from travelling in, out and around the home.

So, What’s the Best Type of Insulation?

Unfortunately, there is no straight answer to which is the “best” loft insulation as each serve different purposes. What we can tell you, however, is which insulation product may be best for YOUR specific loft space.

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Best Loft Insulation for…

Cold Lofts

Cold loft insulation should be installed between the floor joists to prevent heat from travelling into the loft space. Loft rolls are a fantastic option for this type of installation and there are a range of different materials you can choose from.

Damp Lofts

If your loft is or is prone to damp, insulation slabs are the go-to. Slabs are easy to install (DIY!), water-repellent and very breathable so won’t be vulnerable to rotting or mould in moisture-prone conditions.

Warm Lofts

To create a warm loft, the insulation should be divided between the loft floor and the underside of the roof. This allows some heat to enter the loft space to regulate the temperature without it then escaping back out through the roof.

The insulation material used for a warm loft should be denser and more rigid than that used for insulating joists. That’s why insulation boards are the best choice. Though unbending in structure, insulation boards can be easily cut down to size to fit snugly between the rafters for optimum thermal efficiency.

Storage Space

Want a cosy warm home but have nowhere else to store your Christmas decorations? By using rigid insulation boards you can add effective insulation to your loft without sacrificing any vital storage space. Simply store your items directly on top for safe and easy access whenever you need. 

Large Loft Spaces

If you’ve got a large attic space to cover, you’ll want an insulating material that can cover a wide area in quick time. Perfect for fast DIY installations, insulation rolls can be simply spread over the joists across one continuous length.

Compact/Inaccessible Loft Spaces

Whilst insulating an inaccessible loft space can seem like an impossible challenge, it’s a task that can be effectively handled with the help from a spray foam or loose-fill insulation.

Commonly Asked Questions About Loft Insulation

Which Loft Insulation Lasts the Longest?

The lifespan of your loft insulation can be effected by a range of different factors including quality of the material, quality of installation, leaks or water infiltration, physical damages and even unwelcomed pests.

If you’re on the hunt for a durable insulator that offers a lot of highly resilient properties, the innovation of spray foam insulation stands up very well to the test. By not retaining water and resisting damaging mould growth, spray foam has the potential to last a very long time, providing excellent thermal efficiency for years into the future.

Which Loft Insulation is Cheapest?

In general, loft rolls tend to average out at the cheapest option available currently on the market. Our fantastic Knauf Earthwool Glass Mineral Insulation Roll starts at just £23.09 per m²! A brilliantly affordable choice for homeowners on more of a budget.

Best Loft Insulation for DIYers

If you’re planning on DIYing the installation yourself and are on the hunt for an easy-to-install material, insulation rolls and slabs are definitely the way forward. They are very straightforward to fit into a wide range of loft spaces plus can be easily cut when needed create the perfect fit.

Best Loft Insulation for an Eco-Conscious Home

It has never been as crucial as it is now for us to implement more sustainable and eco-conscious products into our lives and into our homes. But did you know that environmental effort can even stretch to the type of insulation you install?

Natural insulation is cleverly manufactured using eco-friendly materials such as sheep’s wool, cork, wood and even hemp. These natural insulators offer a far greener way of insulating the home, lessening your carbon footprint as well as your yearly energy consumption.

For more of an insight into how natural insulation can make a difference in your home, make sure to check our handy article linked here!

Shopping For Your Own Loft Insulation?

If this post has inspired you to install or upgrade your own loft insulation, make sure to check out our extensive range to help you get the job done right. We’ve got a huge selection of professional-grade insulation boards, rolls and slabs available in a variety of high-quality materials. From multi-foil and acoustic to natural fibres and even sheep’s wool insulation, we’ve got everything you could need to warm your home and bring down your energy bills!

For help picking out the right insulation, or for any other questions and queries, don’t hesitate to get in touch with our friendly customer service team who will be more than happy to help! Simply call on 01295 565565, email [email protected], or leave us a message in our handy live chat below.

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