A guide to installing loft insulation, including the materials and labour costs and what the job entails.
Loft insulation is an effective way of lowering your household energy bills by retaining existing heat within your property. Many homeowners are investing in loft insulation because of the financial advantages received in doing so. Loft insulation is predicted to save a household up to £200 each year on their energy bills. Which means that after 2-3 years, loft insulation has practically paid for itself. Using less energy will also decrease your household's carbon footprint, thus having an amazing impact on the environment. Loft insulation can be relatively easy to install and can usually be fitted by a confident DIY-er.
Loft insulation is available in a variety of different materials, with the most common being fibreglass, sheep's wool and mineral wool. Depending on the kind of insulation you choose, the price will vary. On average, fibreglass loft insulation will cost around £300 for a medium-sized UK home. The insulation materials are generally sold in 8 square meter rolls and can cost as little as £20 per roll, ranging upwards of £90 per roll, depending on the material and quality of the insulation you choose. Spray foam insulation is typically more expensive than fibreglass or wool insulation. However, the cost of spray foam insulation can vary greatly in price depending on the quality of the product. On average, you can expect spray foam insulation to cost around £35-£60 per square meter. More effective forms of spray foam insulation may cost between £60-£100 per square meter.
Organic insulating materials such as sheep's wool are excellent for roof insulation due to its proven, natural thermal qualities. Many homeowners desire the organic appeal of sheep's wool insulation, along with the safety value for both the installer and the environment. Not only that, but sheep's wool insulation has also been proven to extinguish itself in the event of a fire, preventing the spread. However, this natural method of insulation is slightly more expensive than alternative options, ranging between £20-£40 per square meter.
The table below is intended to compare the prices between various types of insulating materials. Please note, all prices shown are estimates and should be used as a guide when budgeting for your project.
| Type of Insulation | Materials Cost Per SQM | Area Covered | Total Cost |
|---|---|---|---|
| Fibreglass Rolls | £3 | 16 Square Meters | £48 |
| Mineral Wool | £13 | 16 Square Meters | £208 |
| Sheep Wool | £20 | 16 Square Meters | £320 |
| Spray Foam | £40 | 16 Square Meters | £640 |
Installing loft insulation is a relatively straightforward process, if carried out by a capable person. In the case of installing what's known as a "cold loft" insulation, the fitter will lay the material under the floor joists to prevent heat escaping from the rooms below. The area will need to be prepared before installing the new loft insulation, along with removing any previous insulation.
When installing a type of insulation that comes in 'blanket form', such as fibreglass rolls, this often requires two layers. The first layer will be unrolled and laid directly on the surface between the floor joists, before being cut to the adequate size. A second layer is then added on top of the initial layer, while also covering any visible joists. This second layer will act as an additional thermal barrier, while also building up the depth of the insulation to meet the required level.
When installing spray foam insulation, the process is quite different. Usually, this method of loft insulation should only be carried out by a professional, who will measure the space beforehand to calculate the volume of foam insulation needed. The professional will prepare the space in the same way as the fibreglass method; however, they will also be mindful of any pipes and electrical work that could interfere with the insulation. The spray foam product is then injected into the cavities between the joists, where it will expand and set over the course of a few hours. Once the product is completely set, the insulation process is initiated.
As with any other home improvement projects, you will achieve the best possible results by hiring a professional to carry out the work for you. However, many homeowners have successfully installed loft insulation to their properties themselves and have saved money in doing so. You should firstly familiarise yourself with a few risk factors before attempting to carry out the work yourself. If you do not take the correct precautions when installing loft insulation, you face risking your health as well as the condition of your home.
In the UK, building regulations do not determine the type of material that should be used to insulate a loft space. However, the regulations do state that loft insulation should be a minimum of 270mm in thickness and must have a good level of thermal retaining properties. A qualified and experienced roof insulation specialist will be familiar with the current building regulations, so you can rest assured knowing the job is completed safely.
When fitting fibreglass rolls, or other roll types of insulation, you should begin by ensuring you are wearing appropriate PPE (Personal Protective Equipment), to carry out the work. Fibreglass particles once released into the air can be hazardous to your respiratory system, causing breathing issues as well as dryness to the throat and mouth. It can also irritate the skin and eyes, so ensure that you are wearing appropriate eyewear, gloves and a mask.
You will also need to have adequate access to the floor joists to ensure that you can easily carry out the work. The space will also need to be checked for any signs of damp or condensation due to poor ventilation.
If you install roof insulation materials without treating any damp areas, your materials may retain the moisture, causing additional structural issues that can be costly to repair.
Never cover any pipes or electrical cables with spray foam insulation under any circumstances. Existing pipework may need to be accessed in the future which will be almost impossible to do once the foam insulation has set. The thermal retaining properties of foam insulation can also cause electrical cables to overheat, thus increasing the risk of a fire.
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Here is a list of commonly asked questions regarding having loft insulation installed.
On average, a medium sized loft will take around 2 hours to insulate. This will vary depending on the ease of access to your loft and the type of insulation materials used.
Yes. You can board over loft insulation as long as it is correctly installed and at a minimum thickness of 270mm. Many homeowners choose to board over their installed loft insulation in order to use the space for storage.
Absolutely. The benefits of installing loft insulation greatly outweigh the initial expense of the job. In most cases, loft insulation will pay for itself within the first year of being installed and can save you up to £200 each year on household energy bills.
In some cases, homeowners are eligible to apply for a grant to have loft insulation installed in their home. This will depend on your local authorities and specific energy providers who are participating in the scheme. Some people who receive financial benefits will be able to claim free loft insulation under the government's energy company obligation scheme.
Poorly fitted loft insulation can cause existing damp to worsen if left untreated. Some insulation materials will harbour moisture in an unventilated area, which leads to condensation and damp establishing. If your insulation is fitted correctly by an experienced professional, your home should not suffer from damp issues.
A confident DIY-er can install their own loft insulation. However, the best practice would be to seek the help and advice of an experienced professional to minimize any risk to your health and property condition.
