In many Irish homes, warmth is quietly slipping away — through the walls. If your house feels chilly no matter how high you turn up the thermostat, or if your heating bills seem out of proportion to your comfort, you may be losing more heat than you think.
Cavity wall insulation is one of the quickest, most cost-effective ways to stop this heat loss — and thanks to SEAI grants, it’s never been easier or more affordable to act. So how do you know if your home needs it? Here are six clear signs that your cavity walls might be overdue for an upgrade.
1. Your Heating Bills Keep Climbing
Let’s start with the most obvious red flag: your energy bills are far too high for the comfort you’re getting.
In homes without cavity wall insulation, up to 30% of heat can escape through the walls. That’s a third of your heating effort — gone. If your bills keep rising but your home still feels cold, it could be that heat is leaking through uninsulated or poorly insulated walls.
👉 Homes with cavity wall insulation can save hundreds of euros a year on heating bills. In fact, SEAI reports that a typical three-bedroom semi-detached home can save up to €300–€400 per year.
2. Some Rooms Feel Cold No Matter What
Do you have one or two rooms in your house that are always colder than the rest? Or perhaps your walls feel noticeably cold to the touch, even when the heating is on?
These are classic signs that your walls aren’t holding heat. Proper cavity insulation helps maintain an even temperature throughout your home. It also reduces the need to overheat some rooms just to make others feel bearable.
3. You’re Noticing Damp or Mould on Walls
Insulation doesn’t just trap heat — it also helps prevent condensation. When warm indoor air meets cold walls, moisture builds up, leading to damp patches, mould, and poor air quality.
Uninsulated cavity walls are often to blame. Adding insulation helps maintain a more stable wall temperature, reducing condensation and making your home healthier and more pleasant to live in.
4. Your Home Was Built Before the 2000s
If your home was built before the year 2000, there’s a good chance your cavity walls were never insulated — especially if no retrofitting has been done since. Cavity wall insulation wasn’t widely adopted in Irish home building until the early 2000s, so most homes built before then may be missing this vital upgrade.
And here’s the good news: homes built before 2011 are eligible for SEAI cavity wall insulation grants, which means you can access up to €1,700 in funding to get the work done.
5. You Don’t Recall Any Previous Insulation Work
Still unsure if your cavity walls are insulated? Here’s an easy check:
Look for small, evenly spaced, filled holes in your external walls — about the size of a €2 coin. These are usually the telltale signs that insulation was added in the past.
If your walls are smooth and there’s no record of work being done, chances are your cavities are still empty. A Home Energy Assessment will confirm this, but visual clues can give you a strong hint.
6. Your Home Is Hard to Keep at a Steady Temperature
Does your house heat up quickly, but then cools down just as fast? Or do you find it uncomfortably warm on sunny days and freezing at night?
That kind of fluctuation often points to poor insulation. Without cavity insulation, your walls act more like sieves than shields — letting warmth in and out with little resistance. Installing cavity wall insulation helps regulate your indoor temperature, so your home stays cosier for longer.
Why It Pays to Act Now
Insulating your cavity walls is one of the fastest, lowest-disruption upgrades you can make. The installation process is usually completed in a day or two, and the difference is often felt almost immediately.
Plus, with SEAI grants of up to €1,700, and potential savings of several hundred euro a year, the upgrade often pays for itself within just a few winters.
How REIL Can Help
At Retrofit Energy Ireland Limited (REIL), we help homeowners take the guesswork out of energy upgrades. As an SEAI-registered One Stop Shop, we manage the entire process for you — from your Home Energy Assessment to grant application, insulation installation, and final BER certification.
We work with SEAI-approved contractors, and we deduct your grant upfront, so you don’t have to wait to claim it back. It’s a smoother, simpler way to get the energy-efficient home you want — with none of the hassle.
