How to Insulate a Loft - Easy Step-By-Step Insulating Guide

Loft insulation is excellent if you're looking to reduce energy bills, improve your home's comfort, or create additional living space. A cost-effective solution-insulating your loft can offer you many benefits to your home.

In this comprehensive guide, we'll take you through the easy step-by-step process of insulating your loft and understanding the different types of insulation materials. 

Table Of Contents

• What is Loft Insulation?

• Benefits of Loft Insulation

• Roof Insulation Options Available at JJ Roofing Supplies

• Things You Will Need to Insulate a Roof

• Things to Consider Before Insulating a Roof

• Step-By-Step Guide

• After Care

• Frequently Asked Questions (FAQ)

What is Loft Insulation?

Loft insulation is like a warm blanket for your roof. It can be placed between the horizontal beams (joists) or the angled beams (rafters) in your attic. Its job is to keep your home cosy in winter and cool in summer while saving you money. It's also a clever way to create extra storage space.

Benefits of Loft Insulation

Whether you live in a new-build home or a 1920s cottage in the countryside, loft insulation has several benefits. We've compiled the essential ones for you to consider.

Energy Savings

Roof insulation saves energy bills by preventing heat from escaping from your home in the winter and entering your home in the summer. 

In the winter, heat rises, so it is important to have insulation on your roof to prevent heat from escaping from your home. Roof insulation acts as a barrier, trapping heat inside your home. This allows you to keep your home warm and comfortable without using as much energy to heat it.

The sun can heat your roof in the summer, making your home uncomfortable. Roof insulation helps to keep your home cool by preventing heat from entering your home from the roof. 

According to the Energy Saving Trust, a well-insulated roof can save you up to £285 per year on your energy bills. This means that the cost of installing roof insulation can pay for itself within a few years.

Quieter Home

Installing loft insulation is partially effective at blocking high-frequency sounds such as talking. However, high-impact noise like walking will almost certainly pass through. 

Fibreglass insulation is your best bet if noise isn't an issue and you want a single product that is much denser and excellent at retaining heat. Therefore, loft insulation also acts as a soundproof for your home.

Improved comfort

Roof insulation can help to make your home more comfortable by keeping it warm in the winter and cool in the summer. This is especially important in extreme climates.

Reduced noise pollution

Roof insulation can help to reduce noise pollution from outside sources, such as traffic and aircraft. This can make your home more peaceful and relaxing.

Extended roof lifespan

Roof insulation can help extend your roof's lifespan by protecting it from extreme temperatures and moisture.

Roof Insulation Options Available at JJ Roofing Supplies

JJ Roofing Supplies offers a wide range of roof insulation options to choose from, including:

Insulation board: 

Insulation board is a rigid insulation that is easy to install and can be cut to fit any space. It is available in various thicknesses and materials, including glass fibre, mineral wool, and PIR foam.

Multi-foil insulation:

Multi-foil insulation comprises multiple layers of reflective foil, which trap heat and prevent it from escaping. It is particularly effective at keeping your home cool in the summer.

Wool insulation

Wool insulation is made from sheep's wool or recycled fibres. It is good at absorbing sound and moisture and is fire-resistant.

Things You Will Need to Insulate a Roof:

To insulate your loft, you'll need a few tools and safety gear:

• Rubble bag (for debris)

• Face mask and protective gloves

• Old hand saw

• Tape measure

• Craft knife

• Work light

• Knee pads

• Mobile workbench

Things to Consider Before Insulating a Roof

Storage Area

If you plan to use your loft for storage, you must lay boards over the joists after insulation. Otherwise, the insulation will need to be thicker.

Ventilation

Your home needs airflow to stay fresh and healthy. Ensure you don't block vents, grilles, or airbricks when insulating your roof.

Climate

In cold climates, prioritise materials like fibreglass, cellulose, and spray foam for their ability to retain heat. Hot and humid climates benefit from reflective insulation to reduce heat gain and closed-cell spray foam for moisture resistance. Local climate and building codes should guide material selection for optimal performance.

Inaccessible Loft Spaces

If your loft is hard to reach, use specialised equipment to blow insulation into tight spots using materials like mineral wool, cellulose, or polyurethane foam.

Damp Lofts

Roof insulation prevents heat loss from living areas, potentially cooling the loft space.  If you have damp lofts, this cooling effect may worsen existing condensation issues. 

When installing loft insulation, consider the need for improved ventilation. You must consult professionals before installing loft insulation to address any pre-existing damp problems effectively. 

Warm lofts

Warm lofts insulate the area above living spaces to create a cosy environment. Proper loft insulation helps retain heat, reducing energy bills and increasing comfort. 

Consider materials like fibreglass or spray foam for adequate insulation and consult local guidelines for optimal results. 

Budget

Consider insulation material costs, installation expenses, and long-term energy savings. You may also have to assess government incentives or rebates for energy-efficient upgrades. Balancing upfront expenses with potential energy cost reductions is vital to make an informed, cost-effective choice for roof insulation.

Flat and low-pitch roofs:

Flat or low-pitch roofs require effective insulation to prevent heat loss, regulate indoor temperatures, and protect against moisture infiltration. Common insulation methods for flat roofs include rigid foam boards, spray foam, or built-up insulation systems. Proper insulation can improve energy efficiency and extend the lifespan of the roof.

Safety Tips: Insulating a loft can be challenging, so safety is crucial. Here are some tips:

• Before touching any cables, turn off the power at the central consumer unit.

• Ensure that the passage to your loft workspace is clear by giving other household members a heads-up before you start work. Nothing can be more frustrating than having obstacles obstructing an already demanding journey in and out, so take steps now to ensure smooth sailing afterwards!

• Movement can be complex if your loft floor needs to be adequately boarded. Never stand on the plasterboard because it will not support your weight; only stand on the ceiling joists if necessary.

• It is generally recommended that a 75mm gap should be left between the insulation and any hot chimneys, flues, or recessed light fittings, but check the manufacturer's instructions first.

• Reduce trips into and out of the loft by making sure you have everything you need before you go. This includes all the tools and materials you'll need for your loft project and the ubiquitous mobile phone.

• Wear safety goggles, a suitable face mask, knee pads, and protective gloves when installing your insulation.

Step-By-Step Guide

While you should get professionals to insulate your loft, if you decide to insulate an attic yourself, keep the following in mind:

Step 1:

Trim larger width rolls (1140mm) to the desired width based on the spacing of your joists. Then, using a panel saw partially cut perforations while still in their packaging.

Step 2:

Begin in one corner of the loft and get back to the loft hatch. Place your walkboard at an angle to the adjacent joists. Leave a 25mm gap and lay the first loft roll at the eaves, allowing ventilation and preventing condensation. There's no need to remove the silver wrapping from encapsulated insulation when laying it. Instead, roll it out with the silver side up.

Step 3:

Continue unrolling across the loft floor area between the joists. After you've unrolled your first length, gently push the insulation against the posts to ensure no gaps are left, but don't compress it. Remember that the insulation will take some time to reach its full height. Fluff it gently with your hands to help it get its full depth.

Step 4:

If the roll is not enough, take out a new one and put the joints tightly together. Again, the insulation should be distinct.

Step 5:

Upon reaching the beam, trim the insulation flush using the shaft and restart from the opposite side, working from the eaves. Use a sharp knife to cut the insulation. Sandwich the insulation between two boards and put the top board as a guide. Then, run the knife along the edge for a straight cut. Use giant scissors for small or complex amounts, such as around pipes.

Step 6:

Trim the insulation to the required amount and put it between the joists similarly for more expansive areas. Again, you should keep insulation from being packed or compressed into awkward corners.

Step 7:

Lay across the entire loft area until the base layer is covered.

Step 8:

Put down the second layer. When laying the second layer across the top of the joists, do not cut any wide rolls into narrower ones. This will aid in the laying process by reducing joins and gaps. Instead, place the first roll of the top layer perpendicular to the base layer. Repeat until the second layer covers the area.

After Care

Now that you know how to insulate a loft, you should maintain your loft insulation by ensuring the following:

• Avoid putting weight on the insulation or storing items, as this will reduce efficiency.

• Insulation is relatively simple to maintain. Keep it dry and avoid weighting it because the more compressed the insulation becomes, the less effective it becomes.

If you plan to insulate a loft, visit our website to order material. We offer a variety of high-quality roofing products across London and Hertfordshire. If you prefer looking at the material in person, click on the store locator and find the nearest store.
 
Alternatively, you can message us at web.sales@jjroofing.co.uk or 0333 700 1111. 

Frequently Asked Questions (FAQ)

Can you lay loft insulation on top of the boards?

No, you should not lay loft insulation on top of the boards. This can compress the insulation and reduce its effectiveness. It can also create a condensation risk, damaging the roof timbers. The correct way to insulate your loft is to lay the insulation between the joists.

How much does it cost to insulate a loft?

You may expect to pay about £5 per square metre for blanket insulation, £7.50 per square metre for loose-fill Insulation, £10 for insulation boards, and £55 for blown-fibre Insulation, which also includes installation. These approximate rates per square metre demonstrate the additional expense of employing blown-fibre Insulation. The average cost of loft insulation in the UK is around £300-£400 for a detached house, depending on the size of the loft and the type of insulation used.

Can you insulate a loft yourself?

Yes, you can insulate a loft yourself if it is accessible and has no issues with condensation or dampness. It is a relatively straightforward job, but you should follow the instructions to ensure the insulation is installed correctly.

Should you insulate between the rafters?

When insulating a roof, you have two main options: protecting between and beneath the rafters (cold roof) or between and above the rafters (warm roof). Rafters typically have depths ranging from 100 to 200 mm. Therefore, the insulation between the rafters should ideally be around 50 to 175 mm thick. However, it's often necessary to add additional insulation because more than this thickness is needed to meet the required U-values specified by building regulations.

Should I remove the old loft insulation before laying new ones?

Whether or not you should remove old loft insulation depends on a few factors. If your existing insulation is in good condition and is still effective at keeping your home warm, then there may be no need to remove it. However, if the insulation is damaged, wet, or mouldy, it should be removed and replaced.

How many layers of loft insulations do I need?

The number of layers of loft insulation you need depends on the type of insulation you are using and the desired R-value. The recommended R-value for loft insulation in the United Kingdom is 270mm. To achieve this, you need a single layer of 270mm insulation or two layers of insulation totalling 270mm.

How many years does loft insulation last?

According to Energy Savings Trust, loft insulation has a 40-year lifespan if installed correctly.