Interior Design for House Extensions in Ireland: A Practical Guide to Planning a Space You’ll Love

When you’re building a house extension in Ireland, it’s easy to get consumed by square metres, drawings, and planning permissions. But it’s what you do inside the new space that makes it genuinely life-changing. Interior design isn’t just colour charts or Pinterest boards — it’s the plan for how your family will live, move, cook, relax, study, and entertain, now and in the future.

Whether you’re opening up a bright kitchen-diner in Rathfarnham or creating a cosy living space in Knocklyon, this guide walks you through the big decisions that turn floor area into a beautiful, hard-working extension.

1) Define Purpose & Functionality (Before You Touch Paint or Tiles)

Every successful interior starts with a clear purpose. Ask:

• Primary function: Kitchen-diner, family room, playroom, home office — or a flexible combination?

• Daily life: Quiet weeknights, messy breakfasts, weekend entertaining — what has to work brilliantly?

• Storage & circulation: Where do bags, coats, toys, bins, laundry actually live?

• Future-proofing: Today’s toddler zone might be a teen hangout, a second office, or a studio in five years.

Pro tip: Write a short room brief (3–6 bullet points) that your designer and builder can reference. It keeps every layout choice honest: Does this decision serve the brief?

2) Choose a Style That Reflects Your Home (and You)

A great extension feels like a natural evolution of your home — not a bolt-on. That doesn’t mean “match everything”; it means considered continuity.

• Complement the existing architecture: Echo a few materials, profiles, or tones so old and new sit comfortably together.

• Balanced contrast: A modern, glazed rear extension can look superb on a period house if details (floor heights, skirting lines, cornice transitions) are handled with care.

• Reference libraries: Build a mood board from Pinterest/Houzz/Instagram and narrow to 2–3 words (e.g., warm minimal, Scandi rustic, modern cottage) to guide choices.

• Edit ruthlessly: Too many feature elements fight each other. Choose one hero (island, wall, light) and let supporting finishes stay calm.

3) Plan the Layout & Flow (Test It in Real Space)

Your extension should be effortless to move through. Think in zones:

• Cook / Prep / Clean: Triangle between hob, sink, fridge. Keep bin & dishwasher adjacencies sensible.

• Eat / Chat: Position table to enjoy light and views; allow chair pull-back and circulation behind.

• Soft seating: Avoid breaking sightlines with the sofa back; define with rugs and lighting rather than walls.

• Garden connection: Frame the view. Align doors/windows with an external axis (path, tree, patio).

• Practical routes: Coat storage by the door, a charging drawer near the table, dog bed out of the walkway.

On-floor testing: Use masking tape or cardboard templates to mark island footprints, dining clearances, or sofa depths. Physically walk the circulation: can two people pass while a dishwasher door is open?

4) Materials & Finishes (Durable First, Beautiful Always)

In family spaces, the order of priority is durability → comfort → style.

• Floors:

  • Engineered wood for warm, timeless character (choose a tough lacquer).

  • Porcelain tile in heavy-use areas (matte or honed finishes hide marks).

  • LVT offers robust, water-resistant performance with softer underfoot feel.

• Worktops:

  • Quartz for low-maintenance durability; sintered stone/porcelain for heat & stain resistance; solid wood for warmth (accept patina).

• Cabinetry & paint:

  • Mid-sheen paints resist scuffs; use scrubbable emulsions in high-traffic zones.

  • Mix closed storage (hide the chaos) with open shelves (display personality).

• Hardware & details:

  • Handles, taps, ironmongery, and door profiles quietly set the tone. Cohesive metals (brass, black, stainless) look considered.

• Acoustics:

  • Hard surfaces amplify noise in open plans. Add soft rugs, curtains, upholstered seating, and acoustic panels where needed.

5) Daylight, Lighting & Mood (Design All Three)

Daylight:

• Borrow light from above (rooflights) and across (wide sliders); design for morning vs. evening use.

• Consider shading to prevent summer glare; specify low-g or solar glass if needed.

Artificial lighting (layered plan):

• Ambient: Ceiling grid or track for general light.

• Task: Pendants over island, under-cabinet strips, reading lamps.

• Accent: Wall washers, shelf LEDs, picture spots to add depth.
  All on separate circuits with dimmers so the room adapts from breakfast bustle to calm evenings.

6) Energy Efficiency & Sustainability (Comfort that Pays You Back)

Great design runs smart. Plan performance at concept stage:

• Fabric first: Insulate floors/walls/roof beyond the minimum where feasible; aim for airtightness and controlled ventilation (meet Part L/Part F).

• Glazing: Choose high-performance units; balance big panes with thermal performance and shading.

• Heating: UFH pairs well with heat pumps; in radiators, specify correct sizing and zoning.

• Lighting: LED throughout with sensible colour temperature (2700–3000K warm white in living areas).

• Controls: Smart thermostats and zoned heating reduce bills.

• Grants: Check SEAI schemes for insulation, heat pumps, and solar PV; improvements can lift your BER and resale value.

7) The Finishing Details That Transform Living

• Storage: Build it in now — bench seating with lift-up lids, shallow cupboards along unused walls, a proper utility or pantry if you can.

• Inside–outside flow: Continue floor tones to the patio; align thresholds; plan an outside light, tap, and sockets.

• Personal layers: Art, textiles, plants, and books make the space yours. Design a couple of “moments” (niche, shelf, gallery wall) for character.

• Noise & privacy: Soft linings and pocket doors can create quiet zones within open plans.

• Maintenance: Specify wipeable paints near doors, removable covers on banquettes, and cleanable grout/sealant details.

Irish Rules & Practicalities (What to Know Before You Build)

• Planning permission: Rear extensions up to 40 m² can be exempt, but conditions apply (height, garden amenity, previous extensions, overlooking). Always check with your local council; what’s exempt in principle can still be restricted by site context.

• BC(A)R compliance: New dwellings and many extensions require a Commencement Notice, with roles for Design Certifier, Assigned Certifier, and the Builder’s declaration, ending with a Certificate of Compliance on Completion.

• Building Regulations: Expect to address Part A (Structure), Part B (Fire), Part E (Sound), Part F (Ventilation), Part L (Energy), Part M (Access).

• Professionals: Use properly qualified and insured teams (RIAI/Engineers Ireland for design; Safe Electric/RECI for electricians; RGI for gas; reputable, insured builders).

• Neighbour relations: Plan glazing, boundary walls, and overshadowing with courtesy; good drawings and early conversations avoid objections.

• Insurance & safety: Ensure site insurance, HSA-compliant safety, and waste management plans are in place.

Costs, Fees & Timelines (So You Can Plan Calmly)

• Architectural drawings: Often €1,500–€3,000+ depending on complexity; 3D visuals and engineering add costs but reduce risk.

• Construction: Varies widely by scope/spec; add 10–15% contingency for unknowns.

• Timeframes:

  • Small rear extension: ~10–14 weeks

  • Medium renovation/open-plan reconfiguration: ~12–24 weeks

  • Whole-house refurb + extension: 6–12 months
    Expect weather, supply, and certification checks to influence schedules; build some flexibility into move-in dates.

PAA-Style FAQs (What Homeowners Ask Most)

How do I get plans drawn up for an extension?
Hire an architect or a design-and-build contractor. Start with a site survey and a design brief meeting; progress to sketches, planning strategy (if required), and technical drawings for quotes and construction.

What are the rules for planning extensions in Ireland?
Rear extensions up to 40 m² can be exempt if they meet criteria on height, boundaries, and private open space. Front/side changes, protected structures, or previous additions can alter requirements. Always confirm with your local authority.

How much do drawings cost?
Basic drawings typically €1,500–€3,000+; add for planning applications, structural engineer input, detailed schedules, or 3D modelling.

Do I need architect drawings for an extension?
Not always legally — but they’re strongly recommended. Good drawings enable accurate pricing, compliance, and smoother builds with fewer variations.

How do I make interiors energy-efficient?
Invest in insulation/airtightness, high-spec glazing, efficient heating (UFH/heat pumps), LED lighting, and smart controls. Explore SEAI grants.

Final Thoughts: Make Space That Works as Hard as You Do

Interior design is the soul of your extension. Done well, it turns extra square metres into the best-loved part of your home — bright mornings, messy creativity, quiet evenings, effortless entertaining. Take your time to plan purpose, flow, finishes, and performance; the payoff is a space that feels right on day one and keeps working for years.

Ready to Plan Your Extension?

EverBuild can help you shape the vision, the drawings, the compliance, and the build — and we’ll sweat the interior details that make everyday life easier and better.

📞 Get in touch with EverBuild for a friendly consultation, a clear timeline, and a transparent quote. Let’s design an extension that looks beautiful — and lives brilliantly.