London House Extension Specialists

What Is The Best Loft Insulation?

It is common knowledge that loft insulation is crucial to keep your home warm and reduce your energy bills. But when you scratch the surface, there is more to consider. This article will give you some insight into loft insulation and answer the most common questions about it.

loft insulation

What is the purpose of insulation?

In simple terms, insulation slows down the transfer of heat from inside to outside or vice versa. A standard house that has upstairs ceilings and a lost will not retain heat well. This is because heat will rise and easily pass though the ceiling boards, warming the air in the loft and quickly seeping out into the atmosphere. In order to avoid feeling cold downstairs, the occupants would have to crank up the heat and leave it on for longer – this is expensive and carbon-intensive.

Insulation will slow down the movement of heat from downstairs to upstairs and from warm spaces to cold ones. It resists the upward movement of heat, meaning the home stays warmer for longer. Moreover, it has the opposite effect in the summer. When the weather is hot and sunny, a well-insulated loft will become very warm but that heat will not penetrate into the cooler air of the home so easily.

How much money could proper insulation save you?

According to data from OVO Energy, you could make the following savings on your annual energy costs by insulating your loft:

  • Detached house: Save £240 per year by purchasing loft insulation for ~£395.
  • Semi-detached house: Save £140 per year by purchasing loft insulation for ~£300.
  • Mid-terrace house: Save £135 per year by purchasing lost insulation for ~£285.
  • Bungalow: Save £200 per year by purchasing loft insulation for ~£375.

What is the best type of loft insulation?

There are various types of loft insulation and the best choice for your home will depend on factors like how you use the loft and its shape and size. Here are the most common loft insulation types and the main advantages/disadvantages of each:

Loose-fill insulation

This is exactly what you might expect; it involves spreading a loose, lightweight material all around the loft. The material may be something like cellulose fibre, cork granules, recycled newspaper or mineral wool, and can be placed over existing insulation or used independently. The main downside of this option is that it can be a bit messy, but it is very easy to apply to awkwardly-shaped or smaller spaces as it is very easy to apply.

Blanket insulation

This is usually the cheapest option and thus the most common. It comes in rolls made from felt that is backed with rock, mineral fibre, glass or foil. It is very simple to fit, so you may not even need to pay for a professional to install it. However, this type of insulation is not suitable for the roof itself.

Sheet insulation

This is supplied in fairly solid sheets that can be applied to the roof itself. It provides highly-effective insulation for the loft space. You can even decorate over it, so it is a very good option for loft conversions. The main disadvantage is that it tends to be an expensive option compared to other types of insulation.

Spray-on insulation

This type of insulation involves hosing insulated foam over the area, so it should only be done by a professional. It is sometimes used in conjunction with rolls, particularly where there are nooks and crannies to be filled. Hard-to-reach parts like the undersides of roofs and areas surrounding water tanks and pipes are often insulated this way.

Blown-fibre insulation

This is another type of loose material insulation, composed of a range of lightweight, recycled materials. As the name suggests, this type of insulation must be blown into the loft space using special machinery, so it is best handled by professionals. It is good for getting into hard-to-reach places, but it can be pricey and you won’t be able to install it yourself.

Where does insulation go?

In most buildings, insulation is installed between the roofing joists – those horizontal timber components on the underside of the roof. They rest on top of the ceiling below and, for best performance, it should be double-thick, with the top layer running perpendicular to the bottom one.

We call this form of insulation ‘cold loft insulation’. This is because everything above it will be cold during winter. This cold can cause problems with pipes and tanks, as the water in them can freeze. This is why it’s important to have pipes and lag tanks insulated as well.

If you plan to use your loft for storage, you will want to lay down floorboards to be able to walk around and store your items. With doubled-up insulation, you may need to raise the height with spacers as the depth of the joists is usually the same as a single layer of insulation.

What about loft conversions?

If your loft is to be used as living space, the considerations are different. You will need a warm roof construction wherein the insulation is installed on the underside of the roof. This type of insulation is more expensive, and there are two reasons for this:

First, it requires more specialist work and can’t really be done as a DIY job. Insulating between roof rafters is much more difficult because everything is upside-down – it’s usually down with spray foam or normal insulation help up using boards.

Second, there are more surfaces to insulate. The roof has a larger surface area than the floor, and you will also have to insulate external walls, chimney breasts and party walls. All of this adds up to more work and more materials, but it is worthwhile to get an extra room and add value to your home.

Are flat roofs eligible for insulation?

Flat roofs most certainly can – and should – be insulated. It is a specialist job to insulate a flat roof as the insulation is installed on the outside and must be thoroughly weatherproofed. If you don’t believe your property has a flat roof, check carefully to make absolutely sure. It’s possible that there is a flat roof on a bay window or a new extension, and this must not be overlooked. Without insulation, you will be losing heat.

Getting a roof insulated

If you want to install insulation in your roof, there might be financial assistance available to you. Under the terms of the Energy Company Obligation, your energy supplier may be able to offer part-funding for your insulation if your household income is below a certain level.

If you have to have the work done privately, make sure the installer you go with is registered with the National Insulation Association (NIA). This will mean that they have the necessary qualifications to adhere to the relevant health and safety rules and that they will be able to identify the correct insulation type for your roof.

If you plan to do the job yourself, do your research and watch some video tutorials about how to install the most appropriate insulation. Do this before you start buying the materials and installing them. Be advised that you must tread very carefully in the loft. That ‘floor’ you see between the joists is not suitable for standing on – chances are it’s merely some plasterboard or thin wooden boards that will not hold your weight.

Whatever route you take to insulating your loft, welcome to a new world of warmth.