Why Period Homes Are Different
Homes built before 1940 (and many up to the 1960s) were constructed with solid walls of stone, brick, or mass concrete. These walls manage moisture by absorbing and releasing it through the wall fabric. They "breathe."
Modern insulation materials like EPS (expanded polystyrene) and spray foam are vapour-closed. They trap moisture inside the wall, which can cause damp, mould, structural decay, and even timber rot. Using the wrong insulation on a period home is one of the most expensive mistakes a homeowner can make.
Insulation Options for Period Homes
Breathable insulation (recommended)
These materials allow moisture to pass through while still providing good thermal performance:
- Wood fibre boards (internal or external). Excellent moisture buffering. Cost: €30–60/m² for materials plus installation.
- Sheep's wool. Natural, breathable, and good for attic insulation. Cost: similar to mineral wool.
- Hemp-lime. Applied as a render. Good for uneven stone walls. Cost: €50–80/m².
- Mineral wool (semi-rigid). Breathable if used with a vapour-open membrane. Widely available and more affordable.
- Calcium silicate boards. Internal insulation that actively absorbs and releases moisture. Good for damp walls.
Materials to avoid on period homes
- EPS (expanded polystyrene) on solid stone or brick walls
- Spray foam insulation in attics with timber rafters
- Non-breathable external render over stone walls
- Vapour barrier membranes on the warm side of solid walls
Protected Structures and BER
If your home is a protected structure (listed by your local authority, typically Georgian, Victorian, or other heritage buildings), it is legally exempt from the requirement to have a BER certificate when selling or renting.
However, this doesn't mean you can't upgrade it. You can still get a voluntary BER assessment, apply for SEAI grants, and improve comfort. The key is working with specialists who understand heritage construction.
What Works in Period Homes
| Upgrade | Suitability | Notes |
|---|---|---|
| Attic insulation | Excellent | Mineral wool or sheep's wool between and over joists. Check for ventilation at eaves. |
| Internal wall insulation (breathable) | Good | Wood fibre or calcium silicate boards. Requires careful detailing around windows. |
| Secondary glazing | Good | Keeps original windows while improving thermal performance. Often preferred over replacement for heritage. |
| Draught-proofing | Excellent | Sealing gaps around windows, doors, floors, and chimneys. Low cost, high impact. |
| Heating controls upgrade | Excellent | Thermostatic radiator valves and programmable controls. €700 SEAI grant. |
| Heat pump | Depends | Needs good insulation first. Works well with underfloor heating if floors are being replaced. |
| Solar panels | Usually good | Planning may be needed if the roof faces a public road or if the building is protected. |
| External wall insulation | Not suitable | Alters the building's appearance. Not appropriate for stone-faced period buildings. |
Finding a Specialist
Standard insulation contractors may not have experience with breathable systems. Look for:
- Contractors certified in heritage building retrofit
- Members of the Irish Georgian Society or RIAI conservation architects
- Experience with lime-based renders and breathable insulation systems
- References from similar period property projects
A BER assessment for a period home identifies which upgrades are safe and effective for your building type. Homerating.ie has experience with older and heritage properties across Ireland. Book a BER with Homerating.ie →
Frequently Asked Questions
Yes. SEAI grants apply to all homes built before the relevant cut-off dates. However, you must use appropriate materials. Using non-breathable insulation on a solid stone wall could damage the building and may void your grant.
Protected structures and national monuments are exempt from the legal requirement to have a BER when selling or renting. However, you can still voluntarily get a BER assessment and apply for SEAI grants.
Materials like wood fibre, sheep's wool, hemp, or mineral wool that allow moisture vapour to pass through rather than trapping it. Older stone and brick walls need to "breathe" to prevent damp and structural damage.