Attic Insulation is the simplest and most cost-effective way to improve your home’s energy efficiency and save money on your heating costs.

As much as 25 – 30% of your home’s heat can escape through the roof, leading to needless expenditure to keep your house warm.

While many homes already come with some level of insulation in their attic, it can save you hundreds of euro each year by adding more and newer insulation to reduce heat loss.

Attic Insulation
The key takeaways:

  • Anywhere from 20% – 30% of the heat in your home can escape through a poorly insulated attic.

  • Attic Insulation can cost from €2,500 – €6,500 depending on it size and the insulation products.

  • An SEAI grant is available of €1,500 for loft insulation or €3,000 for rafter insulation.

  • Save hundreds of euro each year on your heating bills and reduce your carbon footprint.

Table of Content

What is Attic Insulation

Attic insulation refers to installing insulation in the ceiling or roof of your home to stop heat from escaping.

The insulation products primarily used for it today are mineral or sheep’s wool, rigid board (PID), or spray foam insulation.

Which type of insulation is best for your home will depend on the type of building you live in, the shape of the roof, and what you intend to use the attic space for.

There are two main ways to add insulation to an attic:

  • Loft Insulation: Rolls of insulation, usually mineral woold or sheep’s wool, are installed between and on top of the ceiling joists.

  • Rafter Insulation: Rigid board (PID) or spray foam insulation is installed between the rafters of your building’s roof.

How much does attic insulation cost?

Getting loft insulation will typically cost between approximately €2,500 and €,5000 depending on the size of the attic. Spray Foam insulation is more expensive, costing up to €7,000 to add between the rafters of an attic.

The exact cost of your insulation will depend on the size of the attic space that is being insulated and the insulation products used.

The costs below, which do not include the SEAI grant, are only estimates, and the only true way to know what it will cost you is to get a quote.

How Much Does Attic Insulation Cost
Attic Size Insulation Type Pre-Grant Insulation Cost
45sqm Loft Roll 200mm €2,500
Spray Foam 100mm €2,600
70sqm Loft Roll 200mm €3,200
Spray Foam 100mm €3,500
100sqm Loft Roll 200mm €3,900
Spray Foam 100mm €4,700
150sqm Loft Roll 200mm €5,100
Spray Foam 100mm €6,500

The final price will vary based on the type of home you live in, as different property types receive a different SEAI grant.

Other elements which can affect the cost of insulation can include:

  • Pipe Lagging: If you have exposed pipes in your attic, it would be advisable to insulate them to prevent them from freezing and reduce your energy bills for hot water.

  • Insulated Flooring: Adding insulated flooring down with loft insulation can make the storage space more accessible while also ensuring there is no gap in protection.

  • Attic Stairs: An insulated staircase and hatch will ensure that there is no major gap in insulation at the entrance to your attic.

  • Water Tank Replacement: If you have a galvanised cold water tank, then you will need to replace this with a plastic tank to receive the attic insulation grant.

  • Ventilation: Some homes may need to install additional ventilation if adding insulation at the rafter level.

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Grants for Attic Insulation

An SEAI grant of up to €1,500 is available for loft insulation, and €3,000 for insulating your rafters to reduce the cost of getting insulation.

The size of the grant is dependent on the type of home you live in. The rafter insulation grant is only available through the One Stop Shop Scheme.

The grant is available for all homeowners and landlords as long as the property was built and occupied before 2011.

 

Insulation Type Grant Value
Loft Insulation Apartment (Any) – €800
Mid-Terrace House – €1,200
Semi-Detached/End-Terrace – €1,300
Detached House – €1,500 
Rafter Insulation Apartment (Any) – €1,500
Mid-Terrace House – €2,000
Semi-Detached/End-Terrace – €3,000
Detached House – €3,000

Best Ways to Insulate Your Attic

The two different ways to insulate your attic are with loft insulation on the ceiling joists or with rigid board or spray foam insulation at the rafter.

Which is best for you will depend on if the attic is going to be converted into a living space at any point as it will decide if the attic space itself is insulated or not.

Loft Roll Insulation

The simplest method of attic insulation is to add layers of mineral wool insulation between and on top of the ceiling joists.

This mineral wool insulation can either replace or go on top of existing insulation, such as fibreglass, that most homes will already have in their attic loft.

Adding loft roll insulation is the most energy efficient way to insulate your home, since you are left with a smaller building area which needs heating.

This keeps the warm air in the living space and leaves you with a cold attic, reducing the amount of fuel needed to heat your home.

Rafter Level Insulation

Adding insulation between the rafters of an attic is best done if you are planning to convert the attic to a living space at some point in the future, since it results in a larger envelope with a warm attic.

Rafter insulation is typically installed with one of two methods:

  • Polystyrene (PID) Board Insulation

  • Spray Foam Insulation

Rigid Board Insulation has the advantage of being relatively simple and inexpensive to install. This can be done quickly by a qualified installer, and it is also possible to DIY install.

Benefits of Attic Insulation

There are many benefits to getting attic insulation installed, such as lower heating bills, increased property value, improved comfort at home, and a reduced carbon footprint.

Attic Insulation can reduce your heating costs by 25% on average.

Adding insulation will help to keep your home warm in winter more easily.

Insulation is one of the most surefire ways to raise your home’s BER, and its value.

Adding insulation to your attic can reduce the possibility of damp, mould, and mildew in your attic, or stop affected air from entering your home.

Cutting your heating requirements will reduce your home’s carbon footprint.

Benefits of Home Insulation

Should you get attic insulation for your home?

Whether or not it is worthwhile getting insulation installed will depend on the age of your home, what existing insulation there is, and how old that insulation is.

Many older homes will have some fibreglass insulation installed, typically about 100mm worth.

This will provide some protection, but it would benefit you to add another 200mm of mineral wool insulation on top of that, or to replace it with 300mm of mineral wool.

Attic Conversions

If you have converted, or are planning to convert your attic to a living space, then adding rafter insulation will help to regulate the temperature, keeping it warm in winter and cool in summer.

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How Much Can You Save With Attic Insulation

Attic Insulation at either the loft or rafter, or both, can deliver massive savings on energy bills by reducing the amount of heat lost through the roof.

The exact amount of those savings will depend on the quality and thickness of the insulation installed, and what a homeowner’s heating bills are.

Property Type Heating Requirements Heating Bill Reduction Annual Savings
Apartment 7,480kWh 20% €167
30% €251
Mid-Terrace 7,699kWh 20% €172
30% €258
End-Terrace 8,635kWh 20% €193
30% €289
Semi-Detached 9,875kWh 20% €221
30% €331
Detached 13,563kWh 20% €303
30% €454

*Heating figures based on household gas consumption in 2020. Source Central Statistics Office
** Energy Bills calculated based on Bord Gais price of 11.17c per kWh with 2% discount

FAQs

The thickness of the attic insulation you have installed should be determined by what kind of performance you are looking for in concert with what your budget for the project is. Thicker layers of insulation will provide a better thermal performance, but will also cost more.

Fibreglass or cellulose insulation should probably be inspected after 15 years or so, at which point it may be replaced. However other materials such as mineral wool, polystyrene boards, or spray foam can be good for up to 100 years if installed correctly.

Spray foam insulation should not be applied by anyone other than a qualified professional with the proper protective equipment.

If it has been well installed attic insulation should not require any maintenance on the part of the property owner for the duration of its lifespan.

If your loft roll insulation has become damp, mouldy, or is otherwise at the end of its lifespan, then it should be removed. But if not, then mineral wool insulation can be laid on top of it.

Installing attic insulation can increase the BER of your home by improving it energy efficiency, and studies have shown that each step up the BER scale can add approximately 1% to the value of your home.

Adding insulation at the rafter level is only preferable if the attic is going to be converted into a living area.

If spray foam insulation is used on your roof, it should leave the rafter joists exposed to prevent damp buildup and allow them to be inspected.

If your hot water cylinder is located in the attic then adding insulation to it and the water pipes can help keep your water hotter for longer.

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