Why Insulate an Old Irish House?
Many homes across Ireland were built before modern building regulations required energy-efficient materials. Without sufficient insulation, these homes suffer significant heat loss, making them harder and more expensive to heat. Proper insulation can:
- Cut energy bills by up to 30%
- Increase indoor comfort during winter and summer
- Improve your home’s Building Energy Rating (BER)
- Increase property value
- Lower your carbon footprint
Assessing Your Property: What Type of Walls Do You Have?
Cavity Walls
Homes built after the 1930s in Ireland often have cavity walls—two layers of brick or block with a gap (cavity) in between. This cavity is ideal for blown-in insulation, a relatively inexpensive and non-invasive option.
Solid Walls
Older homes typically have solid walls with no cavity. These are common in properties built before 1930. Insulating solid walls requires more complex solutions such as external wall insulation (EWI) or internal wall insulation (IWI).
Timber Frame Walls
Less common but present in some rural Irish homes, timber frame construction can be retrofitted with insulation, though it requires careful moisture management.
Roof and Attic Insulation
Why It Matters
Up to 25% of heat in an uninsulated home is lost through the roof. Attic insulation is one of the easiest and most cost-effective upgrades.
Attic Insulation Options
Mineral Wool Rolls
- Pros: Cost-effective, widely available, good thermal performance
- Cons: Bulky, can irritate skin and lungs during installation
Blown Cellulose
- Pros: Great for irregular attic spaces
- Cons: Can settle over time, dusty installation
Rigid Foam Boards
- Pros: High insulation values, good for sloped roof rafters
- Cons: More expensive, harder to cut and fit
Spray Foam
- Pros: Airtight, high R-value
- Cons: Expensive, difficult to reverse, may cause ventilation issues if not installed correctly
Cold vs Warm Loft
- Cold Loft: Insulation placed on attic floor; easier to install, but the attic remains cold
- Warm Loft: Insulation installed under the roof; attic stays warm, useful for storage or conversion
Wall Insulation Strategies for Old Homes
Internal Wall Insulation (IWI)
Best suited for solid wall homes where external insulation is not possible (e.g., protected structures).
Options:
- Rigid Insulation Boards: High thermal resistance, thin profile
- Wood Fibre Boards: Breathable, good for historic buildings
- Calcium Silicate Boards: Excellent breathability, ideal for damp-prone walls
- Insulating Lime Plasters (e.g. Diasen Diathonite): Best for uneven or curved surfaces, though more labour-intensive
Considerations:
- Reduces room space slightly
- Can disrupt interiors during installation
- Risk of internal condensation if poorly designed
External Wall Insulation (EWI)
A highly effective method, especially for detached homes.
Advantages:
- Keeps the thermal mass of the walls within the insulated envelope
- Protects against damp
- Can improve exterior aesthetics
Common Materials:
- Expanded Polystyrene (EPS)
- Phenolic Foam
- Mineral Wool
Drawbacks:
- Changes the façade—may not suit heritage properties
- Higher initial cost
Cavity Wall Insulation
Ideal for homes with unfilled cavities, usually built between the 1930s and 1980s.
Common Fill Materials:
- Polystyrene beads
- Mineral wool fibre
- Foam insulation
Process:
- Small holes drilled in exterior walls
- Insulation pumped in
- Holes sealed afterward
Floor Insulation for Irish Homes
Suspended Timber Floors
Found in many pre-1960 homes, these floors are ideal candidates for underfloor insulation.
- How it’s done: Floorboards are lifted, and mineral wool or sheep’s wool is fitted between joists with netting to hold it in place.
Solid Concrete Floors
More complex to insulate unless replacing or refurbishing the floor. Options include:
- Adding rigid foam insulation over the slab with a new screed layer
- Installing a floating floor with insulation and vapour barriers
Windows and Doors: Plugging Draughts
While not insulation in the traditional sense, improving airtightness through upgraded windows and doors significantly boosts energy efficiency.
- Consider upgrading to modern double or triple glazing
- Install airtightness tape around frames
- Use heavy curtains or thermal blinds during winter
The Importance of Ventilation
When upgrading insulation, especially with IWI or spray foam, ventilation becomes critical to avoid moisture build-up, damp, and poor air quality. Solutions include:
- Trickle vents in windows
- Mechanical Ventilation with Heat Recovery (MVHR) systems
- Passive stack ventilation in attics or bathrooms
Special Considerations for Historic Irish Homes
If you live in a listed or protected structure, always consult with a conservation architect or local planning authority before beginning work.
Breathable Materials
Old stone and brick walls were built to absorb and release moisture. Use vapour-permeable materials like:
- Lime-based plasters
- Wood fibre boards
- Calcium silicate boards
Avoid non-breathable modern materials (e.g., PIR foam with foil facing), which can trap moisture and cause decay.
Visual Impact
Internal insulation is often preferred to preserve the external appearance of the building. However, careful detailing is needed to retain skirting boards, cornices, and window reveals.
Home Insulation Grants in Ireland
The Sustainable Energy Authority of Ireland (SEAI) offers several grants under the Better Energy Homes Scheme.
| Insulation Type | Detached House | Semi-detached | Mid-terrace | Apartment |
| Attic | €1,500 | €1,300 | €1,200 | €800 |
| Cavity Wall | €1,700 | €1,200 | €800 | €700 |
| Internal Wall | €4,500 | €3,500 | €2,000 | €1,500 |
| External Wall | €8,000 | €6,000 | €3,500 | €3,000 |
Eligibility: Homes must be built and occupied before 2011 and not previously availed of a grant for the same type of insulation.
Budgeting for an Insulation Retrofit
| Upgrade | Estimated Cost | Notes |
| Attic Insulation | €800–€2,000 | Most affordable |
| Internal Wall Insulation | €3,000–€10,000 | Depends on material and wall area |
| External Wall Insulation | €8,000–€15,000+ | Effective but pricier |
| Floor Insulation | €5,000–€9,000 | More complex for solid floors |
| Draught Proofing | €500–€1,500 | Excellent ROI |
Step-by-Step Guide: How to Begin
- Get a BER assessment: Understand where heat is lost in your home.
- Choose a certified contractor: Look for SEAI-registered installers.
- Apply for SEAI grant: Secure financial support before work begins.
- Start with attic or cavity walls: These offer the highest return on investment.
- Upgrade heating system and ventilation: A condensing boiler or heat pump can complement insulation upgrades.
Conclusion: Make Your Old Home Warm and Efficient
Retrofitting insulation in an older Irish home doesn’t just save money—it preserves your property’s value and enhances comfort. Whether you live in a stone cottage, 1960s bungalow, or Georgian townhouse, the key is to choose the right materials and method for your specific building.
Pair your insulation upgrade with SEAI grants and expert guidance, and you’ll enjoy a cosier home all year round—without compromising its historic charm.
To make the process easier, OSBER offers expert insulation services across Dublin, Kildare, Meath, and Wicklow, with a strong focus on quality, affordability, and SEAI grant support. Contact us today to explore your options and take the first step towards a warmer, more energy-efficient home.