A complete guide to Attic Insulation in Ireland

Introduction to Attic Insulation

We have all heard about the importance of insulation in our homes over the last few years. At the same time keeping energy bills down while not spending a fortune upfront for insulation solutions seems to be harder to achieve. From external wall insulation to air to air heat systems, the upfront costs are hard to justify. With this in mind as a homeowner what should you do? Without a doubt the best value for money and quickest return on investment is attic floor insulation. 

Why attic insulation is important for energy efficiency and home comfort

During colder months, heat naturally rises and can escape through an uninsulated or poorly insulated attic floor. Proper insulation traps the heat inside, keeping the home warmer and reducing the need for excessive heating. 

This is not to mention during hot weather, the attic can become extremely hot as it absorbs the sun’s heat. Even in Ireland without insulation, this heat can transfer into the living areas. Insulation helps block this heat, keeping your home cooler and more comfortable.

Minimising heat loss in winter and heat gain in summer, attic insulation reduces your energy bills straight away. Insulation will also help maintain a consistent indoor temperature throughout the year, preventing hot and cold spots in different rooms. This really does make your home more comfortable, regardless of the weather outside.

The Impact on heating costs

The impact of insulating an attic on heating bills can be significant, with homeowners typically seeing a reduction in energy costs of 10% to 50%, depending on several factors.

Level of existing insulation

If your attic has little to no insulation, then adding a sufficient layer of insulation can reduce heating costs by 30% to 50%. 

Insulating an attic in a house with a partially insulated attic or an attic with Insulation older than 15 years can see reductions of 10% to 30% in their heating bills. 

House Size & Layout

Larger homes or homes with more attic space will see a greater absolute saving, although percentage savings will be similar across different house sizes.

The level of insulation

Depending on how much insulation is laid and the quality of the insulation (R-Value) the results will differ. The aim for most attics will be 300mm of insulation, this provides a R-Value of 6.8m2K/W.

In summary, attic insulation can lead to very noticeable reductions in heating bills, typically saving between 10% and 50% depending on the factors mentioned above. For many homeowners, the investment in attic insulation pays off quickly, especially in a cold country like Ireland where energy savings are most pronounced.

Types of Attic Insulation

Blanket insulation

Blanket insulation, also known as batt or roll insulation, is a common type of attic insulation made from flexible materials like fibreglass, mineral wool, or natural fibres. It comes in rolls and is one of the most cost-effective insulations available.

Advantages

• Cost-effective
• Can be cut to get perfect fit 
• Fire Resistant (Fibreglass & Mineral Wool)
• Effective Soundproofing
• Widely available

Disadvantages

• Air Leaks and Gaps (if installed incorrectly)
• Difficult to install in tight spaces

Blown-In Insulation

Blown-in insulation, also known as loose-fill insulation, consists of small particles of materials like fibreglass, cellulose, or mineral wool. These particles are “blown” into the attic using special equipment, allowing the insulation to fill in tight spaces, irregular areas, and gaps around pipes, wires.

Advantages

• Excellent Coverage and Air Sealing 
• Quick installation 
• Eco Friendly (Cellulose only)

Disadvantages

• Higher Initial Cost
• Settling Over Time (reduce its overall effectiveness)
• Difficult to remove

Spray Foam Insulation

Spray foam insulation is a type of attic insulation that expands on application, creating an air-tight seal as it fills gaps and cavities. It is made from a liquid polyurethane or similar material that, when sprayed, expands and hardens into a foam.

Advantages

• Excellent Air Sealing 
• High R-Value 
• Long lifespan 

Disadvantages

• Significantly higher Initial Cost
• Very hard to remove
• Wires/pipes not accessible 
• High environmental impact
• Over expansion risks (joist damage)

All of the above insulation methods are brilliant at doing their jobs, however you have to take into account the knock on effect of each. The first two options are the ones I would recommend to anyone who asks. This is mainly because spray foam is just not suited at ground level in almost all attics. The advantages are hugely outweighed by the disadvantages, not having access to pipes and wires is really not advisable. 

Overall I believe the blanket insulation is the best choice. The blown in insulation is limited the height of your joists, if you ever want to be able to floor or even move through your attic. Whereas the blanket insulation can be layered as needed and still gives you access to your joists. 

How Attic Insulation Works

So we know how important attic insulation is and the different methods of achieving it, but how does it work? Well its best broken into the main three aspects, R-Value, Heat transfer and Air Sealing.

R-Value and its Importance

The effectiveness of insulation is primarily measured by its R-value, which indicates the material’s resistance to heat flow. A higher R-value means better insulation performance. The R-value varies depending on the type of insulation material, its thickness, and its density.  

Different climates require different R-values for example in Ireland we strive to achieve an R-value of 6.8m2K/W at attic ground level. 

How Insulation Minimises Heat Transfer

Insulation works by reducing heat transfer, which occurs in three ways: conduction, convection, and radiation. In the context of an attic, conduction happens when heat moves through solid materials like walls and ceilings, convection occurs as warm air rises and escapes through the roof, and radiant heat comes from the sun warming the attic.

If you want to know how the insulation actually stops the transfer of heat, it is relatively simple. The insulation traps air inside to create air pockets, the air pockets are really doing the work as they stop the the movement of air thus reducing heat transfer. 

Air Sealing

While insulation is vital, it cannot fully prevent heat loss or gain on its own. This is where air sealing comes into play. Air leaks, in the context of attic floor insulation are often found at the attic opening. The leaks can undermine the effectiveness of insulation by allowing warm air to escape or cool air to infiltrate. 

That is why we offer and always recommend our attic door insulation services, if you have an attic ladder installed this is extra important. We have a retro fitting option that is designed for hinged attic doors that includes both insulation and a high quality draught excluder. 

In some cases our insulated attic door is another solution, it works perfectly with and attic ladder and is fully sealed and insulated and extends your opening to 72cm. This only fits truss roofs or roofs with 56-57cm between joists. 

Signs Your Attic Needs Better Insulation

A common question I get asked is how do I know if I have enough insulation or is my insulation still effective. If you know when your attic was last insulated this is a straight forward enough question to answer, after 15 years your blanket insulation will start to loose its R-value. That doesn’t mean you have to rush to get it replaced but its worth considering. 

Your energy bills are too high! If you feel that you’re paying too much for your heating, one of the first question should be is my attic insulation doing its job. This is a huge sign you don’t have enough or have ineffective insulation. 

A tip for determining if it’s time to replace your insulation is to take notice of the temperatures of each of you upstairs rooms. If you find that they seem to vary in temperature for no other obvious reason, this is a dead give-away that its time to top up or replace your insulation.

Commonly this is also asked when a person has moved into a new house, not knowing the history of the attic makes it more difficult. However the tip above is a good guide, in some cases it’s quite easy to see that the existing insulation is very old and flat. In any case it is worth contacting someone like us to inspect it. 

How to Choose the Right Insulation for Your Attic

You have determined you probably need your attic insulated, so what’s next? Choosing the right insulation or the right company/person to do the job can be a tough choice. So let’s start with the insulation type that is best suited to your attic, although you can get a professional opinion it’s best to have an idea of what you want first.

If you have skimmed through the above section ‘Types of Attic Insulation’ you might have and idea already what would be best suited for the job. From the advantages and disadvantages in that section you may have guessed we don’t recommend spray foam for attics at floor level. Spray foam works best at roof level. The main reasons we won’t recommend spay foam between joists are that;

It covers wires and pipes

Spray foam adheres to surfaces and goes hard; Imagine trying to find wiring or piping to repair, replace or upgrade. Or even the added cost of paying a professional to do it. 

Mould/Rot – If not done correctly

In some cases – if not done correctly, spray foam can trap moisture between layers of insulation or between the foam and the structure of the house. If moisture becomes trapped, it can cause mould growth, rot, or other structural problems.

Costly for limited gains

With all insulation there is an associated upfront cost that pays you back in time. If all insulation methods can achieve roughly the same R-value, the more you spend upfront the longer it will take to start saving you money. Spray foam can only usefully achieve as high an R-value as any other method, so why spend much more upfront. Unless you think you can benefit from its long lifespan.   

Overall I think the disadvantages outweigh the advantages and this method isn’t recommended, so what is? Looking at Blown in insulation you might consider this as an option and you can’t go too far wrong with it. Blown in insulation has excellent coverage and air sealing and has the added peace of mind knowing it’s is pretty eco friendly. But would I use it for my own attic? The simple answer is no. 

For one it has that high upfront cost, again the higher the cost the longer it will take to start saving you money. Secondly it absorbs water, not something you want in your attic. If the insulation absorbs water and isn’t completely dried it can promote fungal growth. This can lead to contaminated air and even structural problems through timber rotting. Last but not least it is messy stuff! I wouldn’t be a fan of having to remove that from my Christmas decoration box every year. 

While blown in insulation is defiantly a viable option all things considered, I still would argue along with many professionals that the tried and tested blanket insulation is the best option. The relatively low upfront cost and availability is a big advantage. If you go for a fibreglass or mineral wool variant it has a great level of fire resistance. The disadvantages of the other methods of attic insulation just don’t come into play with blanket insulation. It is easy to access wires and pipes, it’s easy to remove and it isn’t moisture absorbing.

DIY Installation

If you think you might be up for the job yourself here are some tips to make sure you get the results of a pro. First of all making sure you have everything you might need. 

What you need

Insulation

Buying the correct amount of insulation will stop you having to return to the builders provider and you’ll be glad of that at the end of the job. So calculating the the number of rolls you need is straight forward. The rolls of insulation have the coverage amount marked in meters squared, so make sure you have your overall attic dimensions in meters squared. 

Length x Width = Area 

Simply measure the length and width of your attic and multiply them by each other to get the meters squared. For example you measure 7.8 meters in length and 3.9 meters in width you will have just over 30 meters squared to cover. If your insulation covers 9 square meters you will need 4 rolls (3.3 rolls rounded up). You always want to make sure you have a bit more insulation than you think you need, better than not enough. Note: If you want 300mm of insulation you will need to double 150mm insulation as there isn’t currently any 300mm rolls manufactured.

Where do you buy your insulation? Nearly all builders providers or DIY suppliers stock rolls of ‘Loft Insulation’. Of course prices vary with builders providers usually having better prices. If you are in Dublin you have a good selection of places to get your insulation. Here is a handy list of links to suppliers websites:

Woodies – https://www.woodies.ie/

Chadwicks – https://www.chadwicks.ie/

B&Q – https://www.diy.ie/

CORE – https://www.corebuild.ie/

TJ O’Mahony – https://tjomahony.ie/

Also worth noting you may need access to a van for larger quantities of insulation. 

Ladder & Light

In terms of equipment there isn’t much you need, if you don’t have an attic ladder you will need a good quality ladder. A good ladder is essential to get the heavy rolls of insulation into the attic safely. I wouldn’t use step ladder for this due to instability, you should try get your hands on an extension ladder. Especially important if your attic access is around a staircase.

A good quality light is essential in an attic, the risk of hitting a pipe or falling through the ceiling is exaggerated by not being able to see clearly. For this we use a ceiling hung light plus a head touch. If you have access to a lead light and extension cable you should start with that to get a general light in the attic. The head touch is essential in an attic, it is always directing light to where you need it. If you can only have one light this is the better option, they aren’t too expensive now days either.

PPE – Personal Protection Equipment

Working with Insulation requires a good level of PPE as any contact with the insulation can cause varied levels of irritation. It’s best to really attempt to avoid irritation however it can’t be completely avoided in my experience.

Mask

A mask is essential for this job to avoid upper respiratory tract irritation, when working with insulation it releases fibres into the air that shouldn’t be inhaled. These fibres settle in time and are only throwing the air as a result of insulation being disturbed. A good quality dust/respiratory mask is great to have for DIY and has multiple uses depending on the type of mask you go for. We use the GVS ELIPSE P3 it is comfortable, has washable/replaceable filters, can be bought at a reasonable price (around €30) and protects against a long list of toxic dusts.

Gloves

A decent set of gloves will stop the skin contact with the material but when choosing a pair remember that working in an attic is often times very hot. Try to get a pair that provide a barrier but also don’t cause huge amounts of sweat buildup. 

Clothing

As recommended by the Insulation Institutes safety guide, try to cover as much of your skin as possible while remembering that clothing should be loose. Loose clothing ensures the fibres don’t get trapped in and continue to irritate. Having loose fitting clothes also prevents sweat buildup too, making the job more bearable in warmer conditions. A good solution for the job is a disposable coverall like 3M’s Protective Coverall 4515, it’s loose, breathable and doesn’t have to be washed after.

For full details on health and safety recommendations when working with fiberglass, rock wool and slag wool Insulation from the Insulation institute visit: https://insulationinstitute.org/about-naima/health-and-safety/

Common mistakes to avoid

When installing blanket insulation (also known as batt or roll insulation) on an attic floor, several common mistakes can occur that reduce the insulation’s effectiveness or cause other issues. Here are some of the most frequent ones:

Compressing the Insulation

Mistake: Packing the insulation too tightly or stepping on it during installation.

Why it’s a problem: Insulation works by trapping air in its fibers. Compressing it reduces its ability to trap air, which reduces its R-value (thermal resistance). Insulation needs to remain fluffy to be effective.

Gaps Between Insulation

Mistake: Leaving gaps between sections of insulation.

Why it’s a problem: Any gaps or spaces between batts allow air to circulate through the insulation, reducing its effectiveness. Gaps create thermal bridges where heat can escape.

Covering Ventilation Areas

Mistake: Blocking soffit vents or other attic ventilation areas with insulation.

Why it’s a problem: Proper attic ventilation is crucial for preventing moisture buildup, which can lead to mould, rot, and ice dams. Blocking vents prevents airflow and leads to poor attic ventilation.
Compressing the Insulation

Failing to Insulate Hard-to-Reach Areas

Mistake: Skipping small or hard-to-reach sections, such as corners, around pipes, or under low sections of the roof.

Why it’s a problem: Even small gaps in insulation coverage can create significant heat loss. Consistent coverage across the attic floor is essential for proper insulation performance.

Not Accounting for Attic Hatches or Doors

Mistake: Neglecting to insulate attic access doors or hatches.

Why it’s a problem: Attic doors or hatches are a common source of heat loss. These areas need to be insulated and properly sealed to prevent air leakage. More information on attic door insulation can be found in our blog ‘Attic door insulation – A complete guide to an insulated loft hatch’ we also offer this as a service https://als-atticladders.ie/attic-insulation/attic-door-insulation/ 

Improperly Sealing Air Leaks

Mistake: Installing insulation without first sealing air leaks in the attic floor (e.g., gaps around pipes, light fixtures, and wiring).

Why it’s a problem: Insulation does not stop air leaks. If gaps are left unsealed, warm air can escape through the cracks, significantly reducing the overall effectiveness of the insulation.

Wrong Thickness or R-Value for Climate

Mistake: Installing insulation with the wrong R-value (too low for the climate). See more info

Why it’s a problem: The R-value is a measure of thermal resistance. Attics in colder climates require insulation with a higher R-value to properly retain heat. Using insulation with too low of an R-value will result in higher energy bills and less effective temperature control.

Cost of DIY Insulation

Most often the reason for people taking on DIY projects is to attempt to save on labour costs. With attic insulation lets break down the costs of undertaking a project of this sort.

The most important consideration is your PPE and potential van hire expenses as outlined above. Other costs are costs you would have to cover anyway; if getting a specialist to do the job. If you’re sensible the most you are going to spend on gloves, mask, head torch and clothing will be under €150. So that isn’t too much of an expense. 

Van rental, if you have a regular size house a medium sized van will do the job of carrying the insulation home. You should budget around €150 for this, that should cover a medium sized van for a day including extra protections and insurance. If you are renting a van I would recommend using Enterprise, I have had bad experiences with others and only good with Enterprise.

In total, provided you don’t need to buy a ladder or anything you’re only looking at a cost of €300. 

Let’s look at the cost of the actual insulation, if you have an average sized house that has an attic that is 30 meters squared. You want to cover it in 300mm insulation as you have little to no insulation. The cost of insulation you’d need as of todays prices is around €400 depending on the supplier. This is based on 7 rolls of 150mm insulation. 

The total cost is now at €700, what would we charge for this job? Based on the 30 meters squared of 300mm insulation provided it was an attic without major obstructions we would charge  around €840.

There are savings to be made, €140 in this example. However if you look at the potential risks involved that €140 saving might not feel as big a saving. The most serious risk is falling through the ceiling; walking on joists that are often obstructed from view takes time to get used to. Another risk of laying Insulation is water pipes, you really don’t want to damage a water pipe for obvious reasons. 

In summary the if you are laying the insulation yourself with the objective of saving money, you can save a little but there are risks.

Cost of Attic Insulation

In Dublin the cost of attic insulation varies hugely depending on what type of attic insulation you want and who is doing the job. For this reason I will stick to how we price blanket insulation for attics. We like to be transparent so we have set a squared meter price for insulation, this gives our customers a guide to cost. There are several factors that make up this price and it changes for time to time. It is currently €25m2 as of writing this, material cost is the main reason for change in price. Overall the cost of insulation is calculated by us and other companies based on the following.

Size of your attic

The most obvious and important factor is the size of your attic. The larger your attic is the more material is required and the longer it will take.

Materials required

The thickness of the insulation required will have a direct relation to the price quoted.

Obstructions

Here is a list of possible reasons prices may deviate from the standard cost calculation. 

• Attic Flooring removal  
• Removing existing insulation (if needed)
• Raised Pipes
• Large areas of limited access 

Attic Insulation Maintenance and Upkeep

Attic insulation in general doesn’t need a large amount of maintenance, however there are somethings worth knowing. Insulation when compressed looses its insulating properties, so just be mindful if you are storing anything on it. Insulation should never get wet, if it does find the source and make sure it dries fully. With that in mind here is more insulation specific notes. 

Blanket Insulation

With a new covering of blanket insulation there is very little maintenance required. It has a lifespan of up to 20 years before really loosing its effectiveness, but it is worth keeping an eye on after the 15 year mark as discussed above. If it is moved out of place for any reason ensure it is placed back without leaving gaps.

Blown in insulation

Blown in insulation ‘settles’ and needs to be redistributed every so often and sometimes it can be a good idea to top it up. Again water shouldn’t come into contact with this insulation, it can cause mould and stop it being effective at retaining heat. It also lasts about 20 years in normal circumstances. 

Spray foam insulation

Spray foam needs no maintenance and lasts up to 100 years but has its downsides too as discussed above.

Attic Insulation and Home Resale Value

In Ireland, the property market has increasingly focused on energy efficiency as a crucial factor in determining home value. Attic insulation is one of the most effective and affordable ways to enhance a home’s energy performance, which significantly affects its resale value. With rising energy costs and a growing emphasis on sustainable living, prospective buyers are more inclined to invest in properties that promise lower utility bills and a smaller environmental footprint. One of the key metrics used to evaluate a property’s energy efficiency is the Building Energy Rating (BER), and attic insulation plays a substantial role in improving this rating.

Improving BER and its Influence on Property Value

The BER is an energy performance label for buildings in Ireland, ranging from A to G, with A-rated homes being the most energy-efficient. A higher BER signifies lower energy consumption and costs, making the property more attractive to buyers. Attic insulation directly impacts the BER by reducing heat loss, as up to 30% of a building’s heat can escape through an uninsulated or poorly insulated attic. Proper insulation not only minimises this heat loss but also contributes to a more stable indoor temperature, which results in lower heating demands and energy usage.

Properties with an upgraded BER can command higher prices in the market. In fact, studies by the ESRI have shown that homes with higher energy ratings can sell for 1-10% more than those with lower ratings, depending on the local market and property type. In a competitive housing market like Ireland, an improved BER can be a differentiating factor, especially as energy efficiency becomes a more significant concern for buyers due to governmental incentives and regulations aimed at reducing carbon footprints. Investing in attic insulation can often lead to a noticeable increase in BER, potentially moving a property from a C rating to a B rating, or even from a B to an A rating, which in turn can considerably enhance resale value.

https://www.esri.ie/system/files?file=media/file-uploads/2015-07/JACB201377.pdf

Cost-Effectiveness and Market Appeal

In terms of cost-effectiveness, attic insulation is one of the most affordable energy upgrades available, with the potential to pay for itself in energy savings within a few years. The Sustainable Energy Authority of Ireland (SEAI) provides grants to homeowners for improving insulation, making it even more financially accessible. These grants, along with the lower energy bills that follow a proper insulation upgrade, make attic insulation a compelling selling point. Buyers are more inclined to consider properties where this work has already been done, saving them the cost and effort of future upgrades.

Energy Efficiency and Environmental Impact

Beyond financial considerations, a home’s energy efficiency is increasingly seen as a marker of environmental responsibility. With Ireland’s ambitious climate action goals to reduce carbon emissions, having a well-insulated home aligns with broader societal efforts to combat climate change. This adds another layer of appeal for potential buyers who value sustainability.

Conclusion

In the Irish property market, attic insulation is a key investment that can significantly enhance a home’s resale value. By improving the BER, reducing energy costs, and appealing to environmentally-conscious buyers, attic insulation offers a practical and effective means of increasing marketability. As energy efficiency standards continue to tighten, the value of such upgrades is only expected to grow, making it a worthwhile consideration for homeowners looking to sell or increase their property’s appeal.

FAQ’s – Attic Insulation

The questions we are most commonly are asked about regarding attic floor insulation are as follows:

What thickness of insulation should I have?

Without getting technical the answer is ideally 300mm. If you plan on having a lot of your attic floored 200mm is a better option.  

How much will I save on bills?

As discussed above the answer depends. If your attic has little to no insulation, then adding a sufficient layer of insulation can reduce heating costs by 30% to 50%. 

Insulating an attic in a house with a partially insulated attic or an attic with Insulation older than 15 years can see reductions of 10% to 30% in their heating bills.

What will it cost?