In Ireland, planning permission and the Building Regulations are two entirely separate systems, and a renovation can need one, both or neither. Planning is about whether your project is acceptable for its location. The Building Regulations are technical construction standards. On top of those regulations sits BCAR, the Building Control (Amendment) Regulations 2014, which adds a layer of formal notification and certification for many building works. Confusing the three is one of the most common and costly mistakes homeowners make on a renovation.
A note before you start
This article is general guidance for homeowners, not legal or professional advice. Building control is administered by your local authority and the rules turn on the precise nature of your works. Always confirm your position with your local authority Building Control section and with a registered architect, chartered engineer or registered building surveyor before you start.
Planning permission versus the Building Regulations
Planning permission, granted by your local authority under the planning code, decides whether a development is the right one for its location: its use, scale, appearance and effect on neighbours and the wider area. Many smaller domestic works are exempted development and need no planning application at all.
The Building Regulations are a different thing entirely. They are a set of legal technical standards that apply to the design and construction of new buildings, and to extensions, material alterations and certain changes of use of existing buildings. Crucially, exemption from planning does not exempt you from the Building Regulations. A single-storey rear extension under the planning size threshold may need no planning permission, yet it must still be designed and built to comply with the regulations.
The Building Regulations and the Technical Guidance Documents
The Building Regulations are organised into parts, each lettered A to M, covering matters such as structure (Part A), fire safety (Part B), site preparation and moisture (Part C), materials and workmanship (Part D), sound (Part E), ventilation (Part F), hygiene (Part G), drainage (Part H), heat-producing appliances (Part J), stairs and guarding (Part K), glazing and conservation of fuel and energy (Part L), and access and use (Part M).
Each part is accompanied by a Technical Guidance Document (TGD), published by the Department of Housing. Following the approach set out in the relevant TGD is regarded as evidence of compliance with that part. You do not have to follow a TGD exactly, but if you depart from it you must be able to show you have met the regulation by another route.
BCAR step by step
For relevant works, BCAR sets out a defined process.
- Commencement Notice. Before relevant works begin, you must lodge a Commencement Notice with the Building Control Authority through the online Building Control Management System (BCMS). It must be lodged not less than 14 days and not more than 28 days before work starts, and works must then begin within that window or a fresh notice is needed.
- Appoint the certifiers. For works requiring full statutory certification you appoint a Design Certifier (who certifies the design complies with the regulations) and an Assigned Certifier (who oversees an inspection plan, inspects the works and certifies compliance during construction). The builder also signs undertakings.
- Certificate of Compliance on Completion. When the works are finished, a Certificate of Compliance on Completion is lodged and must be validated and entered on the statutory register before the building may be opened, used or occupied. The authority has 21 days to validate or reject it.
When is a Commencement Notice required?
The size of an extension is not enough to decide this. Dublin City Council explains that an extension of 40 square metres or less which requires planning permission may need a Commencement Notice without compliance documentation. Larger domestic extensions and other works can require a different notice or certification route.
Before appointing a builder, ask your designer and local Building Control office to confirm the notice type, required documents and submission dates for your actual project. Do not treat a planning exemption as an exemption from technical building standards. Local Government Ireland provides an overview of building-control procedures.
The opt-out route for houses and extensions
Since the Building Control (Amendment) (No. 2) Regulations 2015 (S.I. 365 of 2015), the owner of a new single dwelling on a single-unit development, or of a domestic extension, may opt out of the full statutory certification regime. To do so, the owner signs a “Declaration of Intention to Opt Out of Statutory Certification” when lodging the Commencement Notice on the BCMS.
Opting out means you do not have to appoint a Design Certifier or Assigned Certifier. It does not relax the standards: the works must still comply with the Building Regulations in full, and the Commencement Notice and other building control procedures still apply. Many owners still choose to appoint a professional to inspect the works voluntarily, because compliance remains the owner’s responsibility and the certification gives comfort to future buyers, lenders and solicitors. This matters for related works too, such as a full house rewire or an attic conversion, where compliance with the relevant parts is still required.
Who the certifiers are, and fees
The Design Certifier and Assigned Certifier must be a registered architect, a chartered engineer, or a registered building surveyor. Fees are not fixed and depend heavily on the size and complexity of the project, the inspection regime and your location, so the only reliable approach is to get several written quotes and compare what is included. Treat the certifier’s fee as part of your overall professional-fees budget alongside design, surveys and any planning application. For the wider sequencing of approvals and timelines on a domestic project, see our notes on the planning permission timeline and cost and on garden room planning permission.
Keep a project document checklist
Record the planning decision or exemption basis, the applicable building-control route, design drawings, contracts, inspection records and completion documents. Agree in writing who will prepare each document and when. This is easier before work starts than when a sale, insurance query or grant drawdown creates an urgent deadline.
For budgeting, compare the house-extension guide with the planning timeline. This article is general guidance; ask the relevant authority about your specific works.