architectureHouse Extension Dublin
Two-Storey Extensions in Dublin
Home/Services/Two-Storey Extensions

Two-Storey Extensions in Dublin

Double your extra floor area with a full second storey. We build new two-storey extensions from the ground up, and add a full first floor over an existing single-storey extension where the structure allows.

Get Free QuotecallCall +353 1 265 8524

Full First-Floor & New Second-Storey Extensions

A two-storey extension is usually the next step when a single-storey extension or attic conversion can't deliver enough space — typically because the brief calls for more than one extra room, or the existing roof pitch doesn't leave enough headroom to convert. We build both new two-storey extensions and full first floors added on top of an existing ground-floor extension.

Every project includes structural engineering, full planning support and any party-wall agreements your neighbours require, managed by the same project manager from site survey to snag walk-through.

See related work: kitchen extensions, home renovations, or browse all services.

At a Glance

  • schedule
    Typical Build Time16 - 22 Weeks
  • straighten
    Typical Floor Area30sqm - 50sqm
  • location_on
    CoverageAll Dublin City & County

Two Ways to Add a Second Storey

New-build two-storey extension — a fresh extension built from new foundations up, ground and first floor together. Gives the most design freedom, since nothing is constrained by an existing structure.

Full first floor over an existing extension — if a previous single-storey extension's foundations and roof structure can carry the extra load (or can be reinforced to), we build straight up on top of it. This is usually faster and cheaper than a new-build two-storey extension, since the ground-floor structure and groundworks are already done.

We assess which option fits your home at the free site survey, including a structural check of any existing extension you're looking to build over.

Two-Storey Extension Cost in Dublin

Budget EUR 130,000 to EUR 220,000 turnkey for 30 to 50 sqm of new floor area split across both floors. Building a full first floor over an existing single-storey extension typically comes in at the lower end of that range, since the ground-floor structure and foundations already exist.

Every quote is fixed-price, confirmed after a free site survey and structural assessment. See how this compares to other project types in our cost guide.

Planning Permission for Two-Storey Extensions

Most two-storey extensions need full planning permission. Exempted development only covers two-storey rear extensions up to 20 sqm — smaller than most homeowners want, and any extension to the side or front, or over that size, needs a full application regardless.

We prepare and submit the planning application as part of the project, and factor the statutory 8-week decision period — commonly 12 to 16 weeks once further-information requests are accounted for — into your overall timeline from the start. Where your extension sits on or near a shared boundary, we also manage the party-wall agreement with your neighbour.

More cost & planning answers on our FAQ page.

Common Questions

Quick answers homeowners ask before they book a site visit.

How much does a two-storey extension cost in Dublin?expand_more
Budget EUR 130,000 to EUR 220,000 turnkey for 30 to 50 sqm of new floor area split across the ground and first floors. Adding a full first floor on top of an existing single-storey extension is usually cheaper than a new two-storey extension built from foundations up.
Do you need planning permission for a two-storey extension?expand_more
Almost always, yes. Two-storey rear extensions are capped at 20 sqm under exempted development in Ireland - above that, or for anything other than a strict rear extension, you need full planning permission. We confirm exemption in writing before quoting and handle the full application where one's needed.
Can I add a second storey on top of my existing extension?expand_more
Often, yes - if the original extension's foundations and roof structure were built to carry the extra load, or can be reinforced to. We assess this at the free site survey; where it works, it's normally cheaper and faster than building a new two-storey extension from the ground up.
How long does a two-storey extension take?expand_more
Construction typically takes 16 to 22 weeks, on top of planning permission lead time - budget an extra 2 to 4 months for design and a planning decision if full permission is required, since the statutory decision period is 8 weeks but further-information requests are common.
Do I need a party wall agreement for a two-storey extension?expand_more
If your extension sits on or near a shared boundary wall with a neighbour, yes. We manage the party-wall agreement as part of the project, working with your neighbour's own surveyor where one is needed.

Ready to Get Started?

Free site survey, fixed-price quote, fully insured. Call our Dublin 2 team today.

Get Your Free Quotecall+353 1 265 8524