Loft insulation: how to trap heat in

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What is loft insulation and why do I need it?

Did you know?

If your roof is poorly insulated, you can lose up to a quarter of all heat generated in your home!

Improving your roof insulation can improve the efficiency of your central heating system, and you can save a lot on your energy bills. Insulating your loft allows you to retain heat during the cold winter months, whereas in the summer you can keep your home nice and cool.

The main benefits of roof insulation are:

  • Reducing your energy bills.
  • Protecting your home from outside noise.
  • Increasing the value of your home.
  • Reducing your carbon footprint.

However, you’ll only reap these benefits given you choose the right roof insulation for your house, and have the best energy deal for your energy requirements.

So what is loft insulation?

Loft insulation is essentially a panel of material that is built into your roof. It can either be built into the floor of your loft, between the joists, or in the beams that hold the roof up. We’ll get into the different types of roof insulation later. Anyway, what insulation does is trap rising heat, retaining the heat in the house rather than letting it escape from your home. The insulation that is retained between the beams and inside the joists keeps the attic cool as the heat cannot pass up into the attic, keeping the house warm.

This doesn’t just work in the winter by trapping heat, but also in the summer. When heat is trapped, it means that your house won’t get too hot on warmer days.

What is roof insulation made of?

You can choose between cold roof insulation and warm roof insulation. Cold roof insulation is more popular and involves laying down rolls of insulation on the floor of the loft. Warm roof insulation involves fitting the insulation in between the rafters of the ceiling of the loft.

With cold roof insulation, you can choose between rolls of insulation and insulated floor boards. The first is very easy to roll down yourself, and is the more traditional option. You can always lay down boards on top of these rolls if you want to continue using your loft for storage space. Although, the boards will need to be raised so you don’t compress the rolls.

The material you choose for your loft insulation depends on a wide range of factors, such as price, the size of the space to be insulated, and how ‘green’ you want your insulation to be.

Loft insulation is made from a mixture of lot’s of materials, that include:

  • Glass fibre.
  • Sheep’s wool.
  • Woodfibre.
  • PIR board.
  • Hemp.

And other materials.

They all manage to insulate your home, although to varying degrees of efficiency.

Insulation TypeWhat is it?
Mineral WoolMineral wool is very lightweight, despite being made from volcanic rock! It is also inexpensive when bought upfront. Mixed with other materials, it comes in rolls that simply need to be laid down in your loft. However, if you place too much weight on mineral wool, it will compress, losing its efficiency.
Sheep's WoolNatural sheep’s wool is much safer to touch than mineral wool. However, like mineral roll, it can be rolled down to insulate joists. It is very absorbent and prevents dampness. However, it is more expensive when bought upfront, especially since more is generally needed to insulate the same amount of space as other types of wool.
Glass WoolGlass wool - the most popular insulator in the UK! FYI, it’s also called fibreglass. It’s much cheaper than other types of wool, despite being more insulating and effective. It’s very eco-friendly as well, since it’s often made from recycled materials. However, unlike sheep wool, fibreglass is very irritating for the skin, so caution must be taken when it’s put down.
Insulation boardsIf your loft is too big to lay down lots of rolls, insulation boards might be a better choice for you. They aren’t as thick, but they are very insulating. Unlike wool that can’t be compressed, insulation boards can store objects on top of them, so your loft can be used in a functional way as well.
Insulation SlabsInsulation slabs are very easy to fit and install into your loft, so they are becoming more and more popular. Lots of them are made from stone, and they are very fire resistant!

Last modified the August 24, 2020

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What is the most effective loft insulation?

Loft roll is the most popular material used for loft insulation. This is because it’s super easy to install. All you need to do is roll it across the floors of your attic. However, if you use your attic for storage, or leisure space, this might be tricky to roll around fixed objects.

Glass fibre loft roll is a very common choice. The upfront cost of glass fibre loft roll is quite low, which makes it an attractive option. It is good for reducing sound outside, and is also very easy to install, as you just need to roll it out! However, it does have a lot of disadvantages. This is because, if it gets wet, it loses its ability to insulate your home. Also, it can be harmful to the skin and eyes if touched!

Generally, the most effective roof insulation depends on your home and your specific requirements.

Is fibreglass dangerous?

If you are in contact with fibreglass for a prolonged period of time, it can definitely cause breathing problems, so contact should be kept to a minimum. Sometimes, very fine particles of fibreglass can enter the lungs and cause long-term breathing difficulties, such as asthma.

You should avoid touching fibreglass insulation, as it can cause serious skin irritation, such as burning and itching. So it is recommended that you do not touch fibreglass with bare hands.

How thick should my loft insulation be?

In general, your insulation should be around 250mm to 270mm in thickness. It’s always important to check your insulation after having it for a while. Thickness can reduce over time, especially if it’s wool, limiting its insulating properties.

Can I insulate my loft myself?

You can! But it depends on the material you are using. If you are using wool insulation, you can roll it down yourself. However, if your roof is a funny shape, or if you have a number of obstacles, you might need some extra help. Moreover, if you have a problem with dampness, you will need to get a professional in before laying down your insulation. If you have a flat roof, you also cannot lay down insulation yourself.

To insulate your loft yourself, you need to:

  1. Clear out your loft. Make sure there are no boxes and that the space is clear for work.
  2. Measure your loft and buy enough rolls of insulation to fully cover the space. You also need to make sure that you buy enough insulation to measure 270mm thickness across the entirety of the space.
  3. Check for any electricals or wiring in your attic. You will need to make sure that any wires are on top of the rolls of insulation, and not trapped underneath. You need to make sure that they are safely placed and not stretched to remain above the surface of the insulation.
  4. Start to lay down the insulation between the joists in your loft. This will be the first layer, and you will probably need to cut it to size. Do not stretch the material.
  5. Now, you can lay down the second and top layer. You will probably need a thicker second layer to ensure that the rolls reach the appropriate thickness. But this depends on the height of your joists.

Is it possible to get too much insulation?

If you opt for good quality insulation, then it shouldn’t be necessary to get ‘too much’ insulation, as it should do the trick.

However, you can install as much insulation as you like as long as you have sufficient ventilation through your house. This is to avoid the build up of mould and damp.

What about my pipes and tanks in the loft? Save on your energy bills by insulating your loft

Given that, with the right insulation, your loft space will get very cold in the winter time, as heat will be trapped outside of it. So, you need to ensure that your pipes and tanks in your attic are also sufficiently insulated to make sure that they do not get too cold, or even freeze, as this could lead to them bursting.

How much does loft insulation cost?

The cost of roof insulation depends on the number of rolls you need to lay down, and the cost of laying them down. Of course, if you are laying down the rolls yourself, then you can save money on the initial installation costs. But this depends on the type of material you choose to insulate your home, as not all materials are DIY friendly.

Rolls of wool can cost around £20 each, so depending on the size of your loft and the types of rolls you choose, insulating your loft doesn’t need to be crazy expensive. Of course, if you do need a professional to come round and lay down the rolls for you, then a day’s work can cost upwards of £200, which needs to be factored into your budget.

But remember, loft insulation is very cost-effective and can pay for itself many times over. The Energy Savings Trust estimates that you can save up to £215 each year on your energy.

Benefits of insulating your roof

Extra costs to factor in

If you want to use your loft for storage, then you will have to lay down boards on top of the rolls of insulation. This will include some extra costs, especially to make sure that you take into account all of the safety precautions. Moreover, if you experience problems with damp in your loft, then this needs to be taken care of by a professional before you can install any insulation, which may include some extra costs to consider.

Can I get roof insulation for free?

Some suppliers will provide free loft insulation, depending on your housing situation. These suppliers include EDF, nPower, and Eon. This means that they might consider your financial situation in order to determine if you cannot afford the insulation. Moreover, they will probably assess your house to determine if you will benefit much from insulation or not.

If you are concerned about the costs of heating your home, then don’t forget you can always give us a ring and we can switch you over to a new energy plan that better suits your energy requirements and can save you money.


How long does insulation last?

Generally, roof insulation should at least be checked every 15 years. After this time, the insulation might not be very effective. However, some companies have warranties of much longer, even up to 50 years! So, you should check your warranty with your insulation company.

🤷‍♂️Should I remove old insulation first?

This totally depends on the thickness of the material. If the former insulation is less than 25mm in thickness, this means that the insulation is very old, useless, and should be disposed of. However, if the insulation is around 100mm, this can certainly be topped up. If you want to entirely replace the insulation with new material, then it should be taken up completely.

🏠Can I insulate my roof if I have a damp problem?

You must ensure that any issues with dampness or mould are taken care of prior to replacing or installing your roof insulation. This is because the insulation will not be able to work effectively and it will be a waste! In order to fix damp or mould, you must call in a professional.

🏘️I use my loft for storage space – can I still insulate it?

Yes, but you will need to choose warm loft insulation. This means that the insulation will be installed in the planes of the roof, rather than on the floor of the loft. This means that the loft won’t get too cold during the winter, so you can still put it to good use. You can definitely still install this type of loft insulation yourself, however it might be a bit trickier than laying down rolls yourself.

🌱How environmentally friendly is roof insulation?

In short, very! Not only does it save you money on your energy bills, but it also means that less energy is being wasted, since heat is trapped in your home rather than being lost through your roof. This means that you will need to generate less heat in your home to keep it just as warm. Essentially, you waste less, which is great.

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Written by eleanor

Updated on 22 Sep, 2020