How Many Layers of Insulation Do I Need?

Matt Keane
October 20, 2023

Insulation is a bit of a buzzword when it comes to keeping our homes warm and snug, especially with Ireland’s notorious weather. We've embarked on the mission to decode just how many insulation layers strike the perfect balance for Irish homes.

In this process, we’ve conducted exhaustive research and had natters with industry insiders—all in a bid to arm you with essential information about this vital element of your home’s energy efficiency.

Furthermore, this blog post aims to serve as your personal guide through various types of insulation, helping you make decisions on thickness levels based on different factors. We will also shed light on available grants that can ease up this process and even give tips on picking out the ideal material that suits your specific needs. Ready? Let’s get stuck in!

Key Takeaways

  • Attic insulation in Ireland should be around 150mm thick to reduce heat loss and keep your home cosy.
  • Cavity wall insulation is recommended for improving energy efficiency, with a minimum thickness of 100mm.
  • External wall insulation helps regulate temperatures and reduce energy bills in Irish homes.
  • Internal wall insulation can keep your home warm, quiet, and more energy efficient.
  • Floor insulation with a thickness of about 100mm is important for reducing heat loss and saving on heating costs.
  • Factors to consider when determining the amount of insulation needed include climate, existing insulation, and Irish standards.
  • Fibreglass, foam, sheep's wool, and rockwool are popular options for insulating materials in Ireland.

Types of Insulation

There are several types of insulation commonly used in Ireland, including attic insulation, cavity wall insulation, external wall insulation, internal wall insulation, and floor insulation.

Attic Insulation

Attic insulation is a key part of keeping your house warm. It slows down the heat that leaves through the roof. In Ireland, we use something called a 'U-value'. This measures how fast heat moves through the insulating material.

You want this number to be low because it means less heat is escaping! For our attics, experts suggest using 150mm-thick layers between timber joists on your attic's floor for the best results.

So before you start, take a look at your present loft floor insulation. If it's not enough or old and worn out, adding new insulation will definitely help keep your home cosy and reduce energy costs too!

Cavity Wall Insulation

Cavity wall insulation is an important aspect of making your home more energy efficient in Ireland. It involves filling the gap between the inner and outer walls with insulating material to reduce heat loss and improve comfort.

Cavity wall insulation can help keep your home warm in winter and cool in summer, while also reducing energy bills.

To determine if your home is suitable for cavity wall insulation, it's important to consider factors such as the type of construction, age of the property, and any existing insulation.

A professional assessment will be needed to determine if there are any issues that may prevent cavity wall insulation from being installed.

So, the most common materials used for cavity wall insulation in Ireland are mineral wool or expanded polystyrene beads. These materials have good thermal properties and provide effective insulation.

The installation process involves drilling small holes into the external walls and injecting the insulating material into the cavity using specialised equipment. Once installed, the holes are then filled to match the original appearance of your walls.

External Wall Insulation

External wall insulation is an effective way to reduce heat loss and improve energy efficiency in your home. It involves adding insulation to the external walls of your house, which helps keep the heat inside during the winter and outside during the summer.

This can lead to significant savings on your heating and cooling bills. In Ireland, where the weather can be quite unpredictable, it's important to have adequate insulation in your walls.

So, by insulating your external walls, you can create a more comfortable living environment all year while also reducing your carbon footprint.

Internal Wall Insulation

Internal wall insulation is a great way to keep your home warm and cosy in Ireland. It involves adding insulation to the inside of external walls, helping to reduce heat loss and increase energy efficiency.

Insulating internal walls can also help with soundproofing, making your home quieter and more comfortable. It's important to note that internal wall insulation should be done by professionals, as it requires expertise and specialised equipment.

So, they will ensure that the right amount of insulation is installed properly, taking into account factors such as the thickness of existing insulation and the specific needs of your home.

Floor Insulation

To keep your home warm and energy efficient, it's important to insulate your floors in Ireland. Insulating your floors helps to reduce heat loss and can make a significant difference in your energy bills.

The recommended thickness for floor insulation is typically around 100mm. This can be accomplished by using mineral wool or foam insulation slabs or rolls. It's also important to ensure that there are no gaps or voids in the insulation, as this can affect its effectiveness.

So, by insulating your floors properly, you can create a more comfortable living environment while also saving money on heating costs. So don't forget about floor insulation when considering how many layers of insulation you need for your home in Ireland!

Determining How Much Insulation You Need

To determine the amount of insulation needed in your home, consider factors such as recommended insulation thickness for attics, walls, and floors, as well as climate and existing insulation levels.

Recommended insulation thickness for attics, walls, and floors

To ensure optimal insulation in your home, it is important to consider the recommended thickness for the attic, walls, and floors. In Ireland, for attic insulation, it is advised to have a 150-mm layer of insulation between the timber joists running across the attic floor.

When insulating walls, the thickness will depend on whether you are using cavity wall insulation or internal wall insulation. For cavity walls, a minimum thickness of 100mm is typically recommended.

Additionally, when insulating floors, a common guideline is to have an insulation layer with a minimum thickness of 150mm between the floor joists. These recommended measurements help provide effective heat retention and energy efficiency in your home.

Factors to consider (climate, existing insulation, etc.)

When determining how many layers of insulation you need in Ireland, there are a few important factors to consider. First, the climate plays a significant role in determining the amount and type of insulation needed.

Ireland has a temperate oceanic climate with mild winters and cool summers, so it is essential to choose insulation that can effectively regulate temperature year-round.

Another crucial factor is the existing insulation in your home. Assessing its condition and effectiveness will help determine if additional layers are necessary. If your current insulation is inadequate or worn out, adding more layers will improve energy efficiency and reduce heat loss.

Additionally, consider any specific requirements or regulations regarding insulation standards in Ireland. Understanding these guidelines will ensure that you meet the recommended thermal performance levels for your home.

Choosing the Right Insulation Material

When it comes to choosing the right insulation material for your home in Ireland, there are several options to consider. Fibreglass, foam, sheep's wool, rockwool, and cellulose are some of the popular choices available.

Each material has its own unique properties and benefits, so it's important to research and select one that best suits your needs and preferences.


Fibreglass is a popular choice for insulation in Ireland because it is affordable and effective. It is made up of tiny glass fibres that trap air pockets, which helps reduce heat loss and keep your home warm.

Fibreglass insulation comes in rolls or batts, and it can be easily installed by homeowners themselves. It is important to wear protective clothing when handling fibreglass insulation because the tiny fibres can irritate your skin and lungs.

So, make sure to wear gloves, long sleeves, and a mask.

Fibreglass insulation is commonly used for insulating attics, walls, and floors in Ireland. For attic insulation, you should aim for a minimum thickness of 300mm to achieve optimal energy efficiency.

When installing fibreglass insulation in walls or floors, make sure to fill all gaps tightly with no gaps or voids left behind. This will ensure the best performance of the insulation material.


Foam insulation is a popular choice for homeowners in Ireland because of its excellent thermal properties. It can help reduce heat loss and lower energy bills. Foam insulation comes in two main types: spray foam and rigid foam boards.

Spray foam is applied as a liquid, which then expands to fill gaps and create an airtight barrier. Rigid foam boards are easier to install and provide good insulation value. Both types of foam insulation can be used in various areas of the home, including attics, walls, and floors.

Additionally, foam insulation helps with soundproofing and can improve the overall comfort of your home by reducing drafts and cold spots.

Sheep’s wool

Sheep’s wool is a natural insulation material that is becoming increasingly popular in Ireland. It has excellent thermal properties, which means it keeps your home warm in winter and cool in summer.

Sheep's wool can also absorb and release moisture, helping to maintain a comfortable indoor environment. In addition to its insulating qualities, sheep's wool is environmentally friendly and sustainable.

So, it is a renewable resource that can be recycled or composted at the end of its life cycle. Installing sheep's wool insulation requires professional expertise due to the need for correct installation techniques and safety precautions.


Rockwool is a type of insulation material commonly used in Ireland. It is made from volcanic rock and has excellent fire-resistance properties. Rockwool insulation can be installed in various parts of your home, such as walls, floors, and attics.

So, it provides effective thermal insulation by reducing heat loss and keeping your home warm in the winter and cool in the summer.

One important thing to note about Rockwool is its soundproofing capability. It can help reduce noise transmission between rooms or from external sources, creating a more peaceful living environment.

When considering rockwool for your insulation needs, keep in mind that it comes in different forms, such as slabs or rolls. The thickness of the insulation will depend on factors like climate conditions and existing insulation levels.


Cellulose insulation is a popular choice for homeowners in Ireland. It is made from recycled materials like old newspapers and cardboard, which makes it an eco-friendly option. Cellulose insulation is blown into cavities or sprayed onto surfaces, creating a seamless layer of insulation that helps keep your home warm in the winter and cool in the summer.

One of the benefits of cellulose insulation is its ability to reduce noise transmission between rooms. This can be especially useful if you live in a noisy neighbourhood or have loud appliances.

Additionally, cellulose insulation has good fire-resistant properties, providing an extra layer of safety for your home.

When it comes to determining how much cellulose insulation you need, factors such as the climate and existing insulation should be considered. For optimal energy efficiency, it's recommended to have around 300mm of cellulose insulation in your attic and 150–200 mm on external walls.

However, it's always best to consult with a professional who can assess your specific needs and provide tailored recommendations based on your home.

Insulation Grants and Costs

In Ireland, homeowners can take advantage of SEAI insulation grants to help offset the cost of insulation materials and installation.

SEAI insulation grants

If you're an Irish homeowner looking to improve the insulation in your home, you may be eligible for SEAI insulation grants. The Sustainable Energy Authority of Ireland offers these grants to help offset the cost of insulating your attic, walls, and floors.

So, the amount of the grant depends on the type and extent of insulation you choose, but it can significantly reduce your expenses. To avail of these grants, make sure to follow the guidelines provided by SEAI and submit all necessary documentation.

Improving your home's insulation not only helps you save energy and money but also contributes to a more comfortable living environment.

Cost breakdown for different insulation materials

Let's now talk about the cost breakdown for different insulation materials. The cost of insulation can vary depending on the type of material you choose. Fibreglass insulation is a popular choice, and it usually costs around €15 to €20 per square metre.

Foam insulation, on the other hand, can be more expensive, costing between €20 and €30 per square metre. Sheep’s wool insulation is another option that costs around €25 to €35 per square metre.

Rockwool and cellulose insulation are also commonly used in Ireland, with prices ranging from €20 to €30 per square metre. It's important to consider both effectiveness and cost when choosing an insulation material for your home.

Tips for obtaining insulation grants

If you're looking to avail of insulation grants in Ireland, there are a few tips that can help you through the process. Firstly, make sure to check if you meet the eligibility criteria set by SEAI (Sustainable Energy Authority of Ireland) for availing of such grants.

They usually require homeowners to hire a registered contractor to install their insulation. Secondly, gather all the necessary documentation and information required for the grant application, such as quotes from registered contractors and proof of ownership or tenancy.

Lastly, once your grant is approved, be sure to keep copies of all relevant documents for future reference and reimbursement purposes.

Remember, availing of insulation grants can greatly reduce the cost of insulating your home and improve its energy efficiency. Don't hesitate to reach out for assistance or guidance throughout the application process, if needed.

Calculating the number of insulation slabs needed

To calculate the number of insulation slabs needed for your home in Ireland, you first need to measure the area that needs to be insulated. This includes measuring the length and width of each wall or surface that requires insulation.

Once you have these measurements, you can determine the total square footage by multiplying the length by the width for each surface.

Next, you need to know the thickness of the insulation slabs you plan to use. The recommended thickness will depend on factors like climate and existing insulation. It's important to consult with a professional or refer to guidelines specific to Ireland.

To calculate how many slabs are neededdivide the total square footage by the coverage area of one slab. For example, if each slab covers 10 square feet and your total square footage is 1000, then you would need 100 slabs.


In conclusion, the number of layers of insulation you need in Ireland depends on factors such as climate, existing insulation, and the area you want to insulate. It is important to consider these factors and consult with professionals for guidance.

So, by choosing the right insulation material and thickness, you can improve energy efficiency and keep your home comfortable throughout the year. Moreover, make sure to take advantage of insulation grants available in Ireland to help reduce costs and make your home more environmentally friendly.

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