Extending a Home in Ireland: Planning, Exemptions & Budget

Extensions are one of the most common jobs we do, and they're genuinely good value: you're adding usable space and property value without the cost of moving. But two things catch people out — planning and the budget beyond the build itself. Let's take them in turn.

Do you even need planning permission?

In Ireland, certain rear extensions can be built as "exempted development" — meaning no planning application — as long as they stay within set limits. The key conditions usually involve:

• A cap on the floor area of the extension (measured in square metres)
• Not reducing your remaining private open space below a minimum
• Height limits, especially relative to neighbouring boundaries
• Whether the house has been extended before — previous extensions count toward the limit

Go beyond those limits — a large extension, a front extension, extra height, or building close to boundaries — and you'll generally need full planning permission. That's not a problem, it just adds time and drawings to the front of the project.

Exempt doesn't mean rule-free

Even an exempt extension still has to comply with Building Regulations — structure, fire, insulation, ventilation and so on. Exempt from planning is not exempt from building properly. This is where a good builder earns their keep.

The costs people forget

Homeowners often budget for "the build" and get surprised by everything around it. On a typical extension, plan for:

• Design and drawings — and, if planning is needed, the application and any fees
• Groundworks and foundations — the great unknown until you dig; poor ground costs more
• Connecting old to new — knocking through, matching floor levels, re-routing services
• Making good the existing house — where the extension meets it, the old part often needs work too
• Finishes — kitchens, glazing, flooring and heating are where budgets quietly balloon

The extension itself is rarely the expensive surprise. It's the foundations you couldn't see and the finishes you upgraded once you saw the space.

Single-storey, two-storey, or attic?

Each route suits a different problem:

• Single-storey rear extension — best for opening up kitchen/living space; most likely to fall under exemption limits
• Two-storey extension — adds bedrooms and bathrooms, better cost-per-square-metre, but almost always needs planning
• Attic conversion — often the cheapest extra bedroom if the roof structure and head height allow it, though a proper habitable conversion has its own regulations

How we run an extension

We quote in writing, itemised, so you can see where the money goes. We flag likely groundwork risks early rather than as a mid-job surprise, give you a real schedule with milestone dates, and keep the site tidy while you're living alongside it. And we'll tell you honestly whether your idea is likely exempt or headed for a planning application before you spend on drawings.

Thinking about adding space to your home in Munster? Talk to us early — the best time to get advice is before the design is locked, not after.