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Planning a house extension in Dún Laoghaire is one of the most effective ways to create open-plan living, expand your kitchen, or add master bedroom suites without the expense of relocating. With property values in South Dublin among the highest in Ireland, a well-executed home extension adds substantial long-term value.
Constructors.ie is Ireland's vetted construction directory. We connect property owners in Dún Laoghaire with verified, fully insured building contractors who specialize in architect-led extensions, side-returns, and open-plan kitchen renovations.
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Extensions in Dún Laoghaire range from single-storey rear glass-box extensions on Classic 19th-century Georgian and Victorian coastal terraces (George's Street, Corrig Avenue, Tivoli Terrace) transitioning into mid-century residential estates towards Sallynoggin and York Road. Common projects include:
Under Irish planning regulations, you can construct a ground-floor extension to the rear of your home in Dún Laoghaire without planning permission, provided:
DLR Architectural Conservation Areas (ACA): Parts of Dún Laoghaire fall within designated Architectural Conservation Areas (Dún Laoghaire Harbour & Marine Road ACA, Corrig / Crosthwaite Park ACA, Tivoli Road ACA). While standard rear and side elevations are frequently exempt, modifying front-facing Victorian brickwork, decorative granite quoins, or street-facing façades may require planning permission or a Section 5 Declaration of Exemption from Dún Laoghaire-Rathdown County Council (DLR). Always verify boundary clearances and front elevations with your contractor prior to ordering materials.
Construction costs in South Dublin reflect high material quality and structural standards. Below are typical square-metre rates from vetted contractors serving Dún Laoghaire:
| Extension Type | Cost per Sq. Metre | Typical 30m² Build | Typical 40m² Build |
|---|---|---|---|
| Standard Single-Storey Rear | €2,400 – €2,900 / m² | €72,000 – €87,000 | €96,000 – €116,000 |
| Architectural High-Spec (Large Glazing/Alu-Clad) | €2,900 – €3,600 / m² | €87,000 – €108,000 | €116,000 – €144,000 |
| Two-Storey Extension | €2,600 – €3,200 / m² | €130,000 (50m²) | €180,000+ (60m²+) |
In Dún Laoghaire, house extensions typically cost between €2,400 and €3,200 per square metre for standard builds, and up to €3,600+ per sq. m. for bespoke architectural designs featuring floor-to-ceiling glazing. A standard 30 sq. m. rear extension costs approximately €72,000 to €95,000 excluding bespoke kitchen cabinetry.
Yes, ground-floor extensions up to 40 square metres (430 sq. ft.) to the rear of your home in Dún Laoghaire are generally exempt from planning permission under DLR regulations, provided you retain at least 25 sq. m. of rear garden and comply with height and boundary limits.
A standard 30–40 sq. m. single-storey extension takes between 10 and 16 weeks from ground excavation to turnkey handover. More complex two-storey extensions or full ground-floor structural reconfigurations take 16 to 24 weeks.
For planning-exempt extensions under 40 sq. m., many homeowners work directly with experienced design-and-build contractors who provide in-house structural engineering and architectural drawings. For complex sites, protected structures, or planning applications in Dún Laoghaire, engaging a RIAI-registered architect alongside a vetted builder is recommended.