Our guide on how to insulate a loft

21 - 03 - 2024

If you’ve ever wondered what the best way to insulate a loft is, we’ve got you covered. In this guide, we’ll walk you through how to insulate a loft.

Insulating a loft is a fantastic way to make your home more energy efficient. It helps keep the cold out and the heat in, creating a much more comfortable living environment as well as saving you money on your energy bills and reducing your carbon footprint. 

If you’ve ever wondered what the best way to insulate a loft is, we’ve got you covered. In this guide, we’ll walk you through how to insulate a loft. We’ll also explore the different types of loft insulation available, along with tips for insulating a loft hatch effectively, and how much it’ll cost you to do so.

Why should you insulate your loft?

One of the main reasons you should insulate your loft is because a well-insulated loft stops the heat from escaping your home. Heat rises naturally and if your loft is not insulated properly, the heat in your home will escape. As a result, you’ll more than likely use more energy to try and keep your home warm.

Whether you plan to use your loft space for storage or you want to turn it into an extra living space, insulating between and over rafters is key to creating a comfortable living environment. Insulating a loft will also help reduce your energy bills because it works to keep the heat in your home, meaning less energy is used.

What are the different types of loft insulation available?

There are many different types of loft insulation, each providing their own benefits. The type you choose will rely on a number of different factors including your budget, the level of warmth you want, and how you plan to use your loft space. Here are some of the most popular insulation options available:

Mineral Wool

  • What is it? This particular type of insulation is the most popular and affordable option for many people. It’s primarily made from rock, recycled glass, or slag materials and is commonly supplied in rolls or slabs.
  • What are the advantages? It’s widely available and has good thermal performance. It’s also fire resistant and a cost-effective option for those on a limited budget.
  • What are the disadvantages? The only main disadvantage is that it can create a dusty environment when installing.

Sheep’s Wool

  • What is it? This insulation type is made from natural sheep’s fleece which undergoes a rigorous cleaning process before being turned into insulation. It’s most commonly supplied in rolls.
  • What are the advantages? It’s natural and sustainable, making it an optimal eco-friendly choice. It has excellent thermal performance and is also breathable and is great for regulating moisture.
  • What are the disadvantages? It is typically more expensive than mineral wool.

Cellulose Fibre Insulation

  • What is it? This insulation is primarily made from recycled newspapers or other paper products. It’s blown into the loft space using specialist equipment as opposed to being manually installed.
  • What are the advantages? It has excellent thermal performance and has good eco-credentials due to it being made from recycled materials. It’s also great for filling awkward spaces too.
  • What are the disadvantages? It does require professional installation as it needs specialist equipment to do so.

Ultimately, the type of loft insulation you choose will depend on your individual needs. If in doubt, speak to a professional insulation supplier, like JTD Building Supplies, for expert advice on the right material for your property.

Our guide to insulating a loft

Insulating a loft requires some key steps to ensure it’s not only installed correctly, but also retains heat properly so your home is much more comfortable and energy efficient. Here’s our guide to insulating a loft.

Assess your loft’s current insulation condition

The first step to insulating your loft is to check the situation with your current insulation. If you already have loft insulation, you may need to install more. This is because the recommended depth for insulation has increased to 270mm in recent years. If your insulation was installed quite a while back, you’ll more than likely need to add to it.

You can use a tape measure to find out how thick the insulation is. If it’s less than 270mm thick, you should add an extra layer to make sure your loft insulation meets the latest energy efficiency standards. 

If you have old, damp, or damaged insulation, it’s better to take it out completely and replace it with new insulation. It’s important to note that when you disturb old insulation, it can create dust and debris, so be sure to wear the right PPE like a dust mask, gloves, goggles, and overalls.

Prepare your loft for insulation

Before you start installing insulation in your loft, it’s important to prepare the area first. This will include clearing your loft space and moving any stored items so you can move around freely while you work.

It’s very important to keep good ventilation in your loft space, even after you add insulation. That’s why you should ensure any ventilation gaps at the eaves are clear and open and any vents are at least 5mm wide. This ventilation helps stop moisture from building up and potentially causing condensation and dampness that could harm the structural integrity of a roof structure. 

Start insulating between joists

When you start installing your insulation, start by insulating between the joists. Most insulation rolls are made to fit standard joist spacing, but you may need to cut these down to ensure they fit properly. Be sure to measure the space between the joists to determine whether you need to cut them or not.

Once you’ve measured the joist spacing, you can start to place the insulation rolls between the joists. Best practice is to start from the furthest point of the loft hatch and work your way back. Make sure the insulation fits snug without being compressed or any gaps showing. 

When you reach objects like pipes or wires, use a long knife to cut the insulation. Make sure you lay the second layer of insulation at a right angle to the first layer as this will help keep the joints staggered.

Insulating a converted loft

If you’re adding insulation to a converted loft, you should insulate both between and above the rafters. It is usually easier to fit rigid insulation boards between rafters compared to using rolls of insulation when insulating a converted loft.

Very similar to insulating a normal loft space, the first step to insulating a converted loft, is to measure the space between the rafters carefully. Then, cut the boards to size with a saw, remembering to wear eye protection. Once you have cut the right size, fix the insulation boards to the underside of the roof rafters.

When fitting the insulation boards, make sure there is a 50mm space between the insulation and the roof covering as this gap allows air to flow, preventing any future moisture problems.

Insulating a loft hatch

A lot of heat can escape from your loft hatch if it isn’t well insulated, but it’s an easy fix. Here are some quick tips for insulating a loft hatch:

  • Cut a piece of insulation to match the size of the loft hatch using leftover insulation from your rolls.
  • Make sure it’s at least 270mm thick so it meets the minimum energy efficiency standards and the rest of the insulation in your loft.
  • Attach the insulation to the back of the loft hatch with staples or tacks. If you’re using insulation boards, use strong adhesive to stick the board to the hatch.

It’s also very important to seal any gaps around the loft hatch – paying special attention to where the hatch connects to the frame – to reduce heat loss and draughts. You can use weather stripping or expanding foam tape to seal any gaps.

How much does it cost to insulate a loft?

The cost of insulating a loft can vary on numerous factors such as the size of your loft, the type of insulation you choose, the thickness you select, and the installation process for example. However, the cost of insulating a loft is a worthwhile investment as you can save money on your energy bills in the long run. 

The price of loft insulation in the UK can change, but it typically falls between £30 and £50 per square metre. Again, this price depends on the type of insulation you choose and how much insulation you need. 

If you’re planning to install the loft insulation yourself, you will only need to buy the materials. However if you choose to hire an expert, you’ll obviously need to plan for the costs of labour and materials. 

When thinking about the costs of insulating your loft, it’s important to assess your insulation needs by determining what you’re planning to use your loft for. From here, you can get a better understanding of the type of insulation you’ll need that will meet your budget. If you’re unsure about what insulation you’ll need, you can speak to one of our experts who can provide you with more advice.

Let us help with your loft insulation

We hope our guide on how to insulate a loft has given you a better understanding into how the process works along with the benefits it brings. From saving money on your energy bills, to lowering your carbon footprint, insulating a loft can truly improve your living space and create a comfortable environment for you and your family.

At JTD Building Supplies, we stock a huge range of high-quality insulation, from cavity insulation to loft insulation. On top of this, we stock plasterboard, accessories, and all the tools you need to ensure your loft insulation project is a success. If you’d like to learn more about our insulation products, how to install them, or to get a competitive quote for materials, don’t hesitate to get in touch with us today

Loft insulation FAQs

Can I insulate my loft myself, or should I hire a professional?

Certain loft insulation, such as mineral wool, can be installed by skilled DIYers. However, cellulose fibre insulation requires professional installation due to the tools needed. If you’re insulating a loft yourself, here are some tips: 

  • Make sure you follow building regulations
  • Use good lighting to see clearly
  • Use crawling boards to help spread your weight safely on the joists
  • Wear the correct PPE such as a dust mask, gloves, and goggles

How often should loft insulation be replaced?

Loft insulation is designed to last but installing it correctly can ensure its longevity. If you live in a home that was built quite a while ago, you should check your insulation meets the government recommended thickness of 270mm as this will ensure your home meets current energy efficiency standards.

What is the most effective loft insulation material for the UK climate?

There are lots of different types of loft insulation materials, all with their own advantages. For example, mineral wool and sheep’s wool are both common choices for many homes. But how well they work depends more on how deep you install them and the quality of the installation.

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