Getting your roof and loft insulation is right is a key part of keeping your home warm in winter.
Moreover, it’s essential if you want to save energy at home. After all, the Energy Saving Trust reveals that without it, your home will lose 25% of its heat through the roof.
What kinds of loft and roof insulation can you get?
There are a variety of roof and loft insulation options you can choose from, all made from different materials, and the right choice for your home will depend on several different factors.
‘Selecting the right type of insulation is critical, not only to ensure that the benefits of insulation are realised, but also to ensure that damage isn’t caused to the loft structure,’ explains Tom Garrigan, Technical Director at the Building Services Research and Intelligence Association (BSRIA). ‘The choice depends on how the loft is used, accessibility, and roof type. A competent, accredited installer should evaluate the property and recommend a material and method that meet the U-value requirement (a measure of thermal efficiency).’
Common types of roof and loft insulation include:
- Mineral wool or fibreglass rolls. This type of loft insulation is typically fitted between and across ceiling joints, and is quick to install.
- Blown insulation. Also known as loose or cellulose insulation, this is most suitable for for inaccessible lofts and should be installed by a professional rather than on a DIY basis.
- Rigid insulation boards. These are typically used for loft conversions or rafter-level insulation.
- Natural minerals. Materials such as sheep’s wool or recycled fibre can be especially suitable for homes where sustainability is paramount.
- Spray foam insulation. ‘Spray foam insulation is the premium choice for homeowners who want maximum efficiency and a complete airtight seal in the loft/attic area,’ says Thomas McQuoid, Operations Director at CosyInsulation. ‘Spray foam insulation must be installed by a certified professional and usually comes with a 25-year warranty and lasts the lifetime of the building.’
‘When choosing an insulation contractor, opt for one who offers a range of insulation types, not just one product, adds Thomas. ‘This ensures you receive honest, tailored advice based on your property’s needs — not just the installer’s specialism.’
How much does loft insulation cost?
How much your loft insulation costs will depend on the size of your attic space, and the type of insulation you choose, plus whether you have to rectify any damage, such as water ingress, before it’s installed.
But improving the insulation in your roof can do wonders for your home’s energy efficiency, so it’s definitely money well spent.
Thomas McQuoid says: ‘For an average three-bedroom semi-detached home, typical costs are:
- Fibreglass (DIY): around £700
- Fibreglass (Professional): around £1,000
- Cellulose: around £1,100
- Spray Foam: around £1,400
Before you go ahead and budget to replace all of your existing insulation, get an assessment from an expert. It’s possible that, if your existing loft insulation is in good condition, and you just don’t have enough of it, you could lay new insulation on top of your old material to get the required result.
How much loft insulation do you need?
When it comes to how much loft insulation you need, it depends on how much you have already and whether it meets the requirements laid out in the building regulations.
‘The amount of insulation needed depends on the U-value you’re aiming to achieve – this measures how well your home retains heat.,’ explains Thomas from CosyInsulation.
‘At ceiling level, UK Building Regulations typically recommend a U-value of 0.14 W/m²K. At rafter level, the target is usually 0.18 W/m²K.
‘A professional insulation contractor can calculate the exact depth and material requirements for your property to ensure compliance and optimum performance.’
Can you lay loft insulation yourself?
Technically it is possible to lay some types of roof and loft insulation yourself, but it is much more complex to do than it may seem, and you’ll need suitable PPE gear to ensure you can do it safely, so it’s usually a better idea to get a professional to do it for you.
After all, it can not only be hazardous to your health if you don’t have adequate PPE, but it could cause more problems than it solves if you don’t lay it correctly.
However, in the case of loose fill and spray foam insulation, you will always need a professional to install it on your behalf.
‘Insulation should always be installed by a competent professional to ensure safety and performance,’ explains Tom Garrigan. ‘It is essential that the installation is continuous and maintains proper ventilation in the roof space to prevent any issues. Compression should be avoided to ensure the insulation remains effective, and it’s crucial that mechanical ventilation systems are not obstructed. Additionally, electrical and lighting systems need to be appropriately managed during installation. The specific method and layering depend on the type of insulation material and the structure of the loft.’
When it comes to where the insulation is installed, there are two options and the right one will depend on how you plan to use the space. ‘You can insulate at ceiling level (on the attic floor above your ceilings) or at rafter level (in line with the roof pitch),’ says Thomas McQuoid. ‘Both have their advantages, depending on how you use your attic and the performance you want to achieve. Insulation at ceiling level is typically cheaper and easier to install, and is ideally used where attics are not used as living space. However, a major drawback with ceiling level insulation is that it does not protect the attic space from cold temperatures.
‘Insulation along the rafters of the attic can turn the space into a perfect setting for a home office or hobby room. By creating an airtight building envelope, rafter level insulation dramatically improves energy efficiency and reduces draughts and condensation risks.’
How long will loft insulation last?
When it comes to how long your insulation will last, if installed correctly, using quality materials, it should have a lifespan of decades. Many forms come with a 25 years guarantee, but some can last much longer, even as long as your house is still standing!
But there are factors that can drastically shorten its lifespan, including pest infestation, exposure to water and compression.
What kind of maintenance does loft insulation need?
The good news is that once installed, you shouldn’t have to do any maintenance on your insulation, and in fact, it’s best if it’s left alone. Messing with it could cause gaps which can let heat escape quickly or moisture to get in, which is definitely not what you want.
However, if you start to notice that your home is getting colder, you have inexplicably higher heating bills or you are worried you might have mice or birds in your loft, then it’s worthwhile getting a professional to assess your loft insulation to make sure it’s still in good order.
FAQs
Can you put too much insulation in the loft?
It is definitely possible to put too much insulation in your loft, which is another reason it’s a sensible idea to use a professional to install it.
Installing too much insulation in your roof space can trap warm moist air, leading to damp and mould, which not only damages your insulation, but can also impact your roof structure and your health.
So before you add more loft insulation in the hopes of making your home warmer, make sure you get the advice of an expert who can tell you exactly how much you need.
Can I lay loft boards over insulation?
If you don’t plan on using your loft as additional living space, then the loft makes prime storage space. But it’s important you don’t lay your belongings directly on the insulation. Not only could this cover your belongings in hazardous particles that can irritate your skin and respiratory system when you come into contact with them again, but it could also compact your insulation, which makes it less effective and shortens its lifespan.
If you want to board your loft so that you can safely store items in your loft, then you’ll need to ensure the boards are raised off the insulation so as not to disturb or compress it. Loft legs or loft storage stilts can be picked up from B&Q, from £17.70 for a pack of 12.
As with any energy saving measure, it works best in tandem with other measures too. Take a look at some of the upgrades you can do to make your home warmer.
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