Upgrading or replacing your windows is one of the most effective ways to improve comfort, energy efficiency, and property value. But before you start, it’s essential to understand what the law says about planning permission and building regulations.
Most window replacements qualify as exempted developments, meaning you don’t need planning permission. However, there are clear exceptions, especially if your home is listed in a conservation area, or if you’re changing the appearance of your property.
At Fairco, our products and installation process are designed with full compliance in mind, helping homeowners modernise efficiently and legally.
When planning permission is not required
In the majority of cases, replacing existing windows with similar ones doesn’t require planning permission. According to Planning Leaflet 8: A Guide to Doing Work Around the House, such work is considered exempted development under Irish planning law.
This exemption generally applies when:
- You are replacing windows of the same size, shape, and appearance.
- The work does not materially alter the external look of your home.
- The replacement does not affect protected or designated structures.
These exemptions are outlined under the Planning and Development Act and accompanying Regulations available via gov.ie.
If you’re unsure whether your plans qualify, you can request a Section 5 Declaration from your local planning authority. This provides a formal decision confirming if your project counts as exempt development.
When you do need planning permission
While many upgrades are exempt, several scenarios require planning consent or special permissions:
- Adding or altering window openings
If you’re adding new windows, changing window size, or installing features like bay windows that project outward, you will likely need permission. Such works are considered to materially alter the structure’s external appearance.
- Protected and conservation properties
For protected structures or homes in architectural conservation areas, even replacing existing windows often requires formal consent. This ensures the visual character of heritage areas remains intact.
- Special local restrictions
Some local councils enforce special restrictions, removing permitted development rights. If your property is covered by one, changes that would normally be exempt, such as replacing windows, may require permission.
- Converting windows into doors
Transforming a window opening into a door typically demands planning approval, as this alters both the façade and structure. - Proximity to boundaries and privacy concerns
Certain distance and height rules apply, particularly for upper-floor windows. For example, Wexford County Council’s exempted development guide notes that upper-storey windows must be at least 11 m from a boundary line. Local authorities may interpret this differently, so always confirm locally.
Building regulations still apply to all replacements
Even when planning permission isn’t needed, Building Regulations still apply to every window installation. These ensure safety, structural integrity, and energy efficiency.
The most relevant requirements come from Technical Guidance Document Part L, which deals with the conservation of fuel and energy. Windows must meet minimum performance standards, including:
- U-values: Replacement windows must achieve specific thermal performance targets to limit heat loss.
- Ventilation: Modern regulations require adequate airflow. If your old windows didn’t include trickle vents, new ones must.
- Safety glazing: Toughened or laminated safety glass must be used near doors, low sills, or high-traffic areas.
- Compliance documentation: Installers should provide certification confirming adherence to regulations.
You can review the official standards in Technical Guidance Document L.
How Fairco ensures full compliance
At Fairco, compliance isn’t an afterthought; it’s built into everything we do. Our process ensures your upgrade meets both planning and building regulation requirements from the outset.
- Design assessment: We evaluate whether your project falls under exempt development and design replacements that align with the existing structure.
- Aesthetic continuity: Our systems replicate original proportions and finishes, reducing the likelihood of planning complications.
- Certified performance: All Fairco windows are engineered to exceed Irish energy and safety standards, achieving low U-values and high durability.
- Regulation-ready installation: Every installation is completed by trained professionals following Technical Guidance Documents, ensuring peace of mind and legal compliance.
Heritage Sash, designed for conservation
Fairco’s Heritage Sash windows are ideally suited for conservation areas and protected structures because they are designed to respect the architectural character while meeting modern performance standards. Our sash profiles, slim rails, and run-through horns mirror traditional design details, which aligns with the approach set out in the Architectural Heritage Protection Guidelines for Planning Authorities guidance that emphasises minimal intervention and the retention of original proportions and features in conservation areas. Under these guidelines, any alteration to windows in Architectural Conservation Areas (ACAs) or protected structures must preserve the “character and special interest” of these buildings. By combining faithful aesthetic replication with energy-efficient glass, secure frames, and precise installation, Heritage Sash offers a balance: you maintain regulatory compliance while achieving thermal performance and durability.
Read more about Fairco Heritage Sash in this blog or explore the range here.
The Fairco difference
For most Irish homes, replacing like-for-like windows doesn’t require planning permission. However, once you alter window dimensions, introduce new openings, or work on protected structures, permission or heritage consent becomes necessary. Regardless of planning requirements, Building Regulations always apply.
Fairco helps homeowners navigate this process confidently, combining compliance expertise with premium energy-efficient window systems that enhance performance, comfort, and value.
Thinking about upgrading? Contact Fairco today for expert advice on compliant, high-performance window replacements.
