A Beginner’s Guide to Loft Insulation

Improving the level of insulation is the most effective way you can improve the energy efficiency of your home, reduce your carbon footprint and make significant savings on your energy bills.

You can lose around a quarter of the heat generated through a poorly insulated roof. By insulating the roof space well you can retain this heat and enjoy a cosy home throughout the year.

Investing in insulating your roof will improve your home energy efficiency for years to come; your investment will be recouped quickly, and you will enjoy the benefits for years to come.

This short guide will help you understand the basics of installing insulation including how insulation works, what insulation materials are available, and what you need to consider before you start.

Why insulate your loft?

The benefits of insulating your loft can be seen throughout the year, retaining heat during the winter months and, through the choice of the right materials, you can reduce solar gain and maintain a cool home during the summer. The overall contribution is significant savings on your energy bills

Insulation can be installed either on the sloping roof, between and over rafters, or at ceiling level between or over joists. The choice of where to insulate in your roof will depend on how this space is used we will explore the advantages as we continue through this guide.

Choosing which type of insulation is best for you will become apparent as we work our way through the options available.

What are the benefits of insulating your loft?

Loft insulation offers a range of benefits including:

  • Improving energy efficiency
  • Reducing your carbon footprint contributing to the fight against climate change
  • Reducing your heating/cooling bills
  • Improving your home’s value
  • Reducing the transmission of external noise

If you care about the environment and you want to save money on heating bills, insulating your loft is a sensible first step.

How much money will insulating my loft save me?

Insulating your loft will save you a significant amount of money per year; take a look at these examples (figures from the Energy Saving Trust). 

Type of homeDetachedSemi detachedMid terraceBungalow
Typical cost of loft insulation installation£395£300£285£375
Fuel bill savings per year£240£140£135£200
Carbon dioxide savings per year990 kg580 kg550 kg820 kg

*Typical costs based on average home installation

**Fuel bills based on gas central heating

Energy-efficiency grants might also be available in your area to help reduce the cost. For more information visit the government-endorsed website Simple Energy Advice.

What types of loft insulation are there?

There are many different types of loft insulation which vary in cost, durability and insulating performance. These include traditional insulations such as Glass and mineral wool insulation, Earthwool and other Eco friendly materials, High Density Foam Board insulations and Blown (Loose Fill) Insulation.

Multifoil insulation is fast becoming the first choice for many commercial and domestic projects. Developed for commercial use following its success in the NASA space programme multifoil insulation is made using multiple layers of aluminium foil alternated with foam wadding.

SuperFoil multilayer foil insulation uses sustainable and recycled materials and is available in a range of thicknesses to enable you to select the most appropriate solution for your project. For use in lofts, walls and floors SuperFoil provides you with a solution that is both affordable and effective. Plus, you can be confident in knowing that SuperFoil products have gained the approval of all the major Accreditation bodies and Warranty Approval schemes in both the UK and Europe.

The SuperFoil range now includes SuperFOIL SF19BB and SF40BB, both are fully breathable and combine insulation and breather membranes in one so you won’t need to take additional steps when installing your multifoil insulation in your roof.

Are you confused by R- Values & U-Values?

Both measures are very important and should be considered when you are selecting an insulation material and to assess the performance of the finished floor, roof or wall structure.

Now to clear up the confusion, the R-value is the assessment of the thermal resistance of the material. All materials included in the structure have an R-value. Individual materials do not have a U-Value.

To calculate the U- Value you add together all the R- Values and then divide 1 by the total to get the U-value. The U -Value therefore is the reciprocal of the sum of the R values.

So, the higher the sum of the R-Values the lower the U- Value. Building Regulations determine the U- Values which we are aiming to achieve with our building.

This is where we come in, you don’t need to calculate these values yourself- simply contact our technical helpline and we will do it for you!! .

What is radiant heat transfer and why does it matter?

Most forms of loft insulation such as glass wool and chemical foam insulation work by slowing both conductive and convective heat flow to trap warmer air inside your home.

However, what about that heat loss through radiation? Radiant heat transfer happens when heat hits a flat surface and warms that surface. You might have noticed this effect when you touch the bonnet of your car on a hot, sunny day.

Around 75% of the total heat loss that occurs from your home can occur in this way. That’s why it’s so important to include a radiant heat barrier to improve overall insulation performance, improves comfort in your home and reduce your energy costs.

Multifoil insulations such as SuperFOIL address all three elements, Don’t forget, this is also one of the reasons why NASA chose advanced multifoil technology for their space missions.

More traditional forms of loft insulation such as glass wool, high density foam boards and even natural insulation products do slow down heat loss but have low reflective ratings and high emissivity ratings and don’t offer the same benefits.

What to consider before insulating your loft:

There are several factors that you should bear in mind before you insulate your loft so you can find the optimal solution for your space.

1. Do you want your loft to be a cold or warm space?

When it comes to loft insulation, you can either focus on keeping your living spaces warm and leave the loft cooler, or you can insulate the entire space. This is especially useful if you’d like to use the loft as a living space or would like to use the loft for storage.

To create a warm space, you need to insulate on the sloping roof, the rafters and to create a cold space, you can insulate between and over the joists at ceiling level.

Insulating at rafter level can be a more complex task, but by taking this route you’ll be able to use this extra space as you wish; simple storage or as many people are doing today, expanding the accommodation in their current homes rather than choosing to move.

It is also important to insulate party walls and gable walls as well as any other uninsulated parts of the room to minimise heat loss.

If you’d prefer to focus on your existing home and living space, you can insulate at ceiling level, between and over joists which will improve the comfort of the rooms below and leave your loft cooler.

You can use SuperFoil Insulation whichever option you choose, speak to our team who will be pleased to go through the options available to you.

2. Is the loft already insulated?

Many homes already have some insulation but this most probably doesn’t reach current building standards or no longer offers the optimal level of insulation for your needs.

If this is the case, you can ‘top up’ your insulation relatively simply.

Take the opportunity to upgrade to a high-performance loft insulation material such as SuperFOIL. Call the SuperFoil ‘Technical helpline’ to discuss your project further or submit an enquiry online at www.superfoil.co.uk..

3. Do you have a flat roof?

Flat roofs (those with a pitch of less than 18°) demand a different approach compared with pitched roofs. You can either choose a warm roof, which is when the insulation

material is placed on top of the roof, or a cold roof, which is when the insulation is placed between and under the joists. Seek the assistance of our Technical Team to plan what is best for your project.

4. Does your home suffer from damp?

Condensation can be an issue and it is important to ensure that the insulation is installed correctly following the manufacturers guidelines. Maintaining air flows and ensuring that you have sealed all the necessary cuts and overlaps is an important task.

We always advise you to ensure that there is adequate ventilation and that you deal with any damp problems. It’s always worth asking a builder or damp expert for professional advice.

5. Where are your pipes and water tank?

If your pipework and water tank are in the loft, and you have insulated at ceiling level it is essential to ensure that they are insulated both to prevent burst pipes, damage from the cold and other costly repairs.

If you’re insulating the rafters to create a warm room, there’s no need to worry.

6. Have you insulated your loft hatch?

When you’re insulating the joists without insulating your loft hatch, you might be surprised at the amount of heat that can escape.

That’s why it’s a good idea to fit an insulated loft hatch and place strips of draught-excluding material around the edges to help your home better retain the heat. 

7. Do you have recessed halogen lights in a room below the loft?

If you’re laying your loft insulation over the joists and you have recessed halogen lights in the room below, you will need to take extra precautions to reduce your fire risk.

Simply invest in loft caps/loft covers (fire protectors) and you can protect yourself whilst still enjoying the full benefits of insulation.

If you’d like more information on SuperFOIL insulation products, please contact us directly to find out more or receive a no-obligation quote.


Our FREE guide gives you all the information on saving time and money when insulating your home, and how to really make a difference to the comfort of your rooms.

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SuperFOIL Insulation Guide