County Antrim
Flat-roof rear extensions in County Antrim
Warm flat roofs with lanterns, parapets and long-life membranes. Rear extensions in County Antrim: we cover 7 towns including Belfast, Lisburn and Newtownabbey, with design, approvals and the build under one contract.
Flat roofs are the usual choice for rear extensions because they stay below first-floor windows and take a lantern neatly. County Antrim has terraces near the centre, semis on the edges and many detached houses and bungalows in the surrounding countryside, where plots are often generous.
How much does a flat-roof rear extension cost in County Antrim?
In County Antrim, our guide for a flat-roof rear extension is £1,650–£2,700 per square metre including VAT for a standard specification. Northern Ireland prices are the lowest in our range.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £20,000–£32,500 |
| 4 m wide × 5 m deep (20 m²) | £33,000–£54,000 |
| 4 m wide × 6 m deep (24 m²) | £39,500–£64,500 |
These are guide ranges; the written quote after the survey is the figure that counts.
Do you need planning permission in County Antrim?
In Northern Ireland the Planning (General Permitted Development) Order (Northern Ireland) 2015 allows a single-storey rear extension of up to 3 metres on an attached house or 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres within 2 metres of a boundary. Building control approval from the council is still required.
Insulation and glazing follow Technical Booklet F1 in Northern Ireland, checked by council building control.
Conservation areas, Areas of Outstanding Natural Beauty and listed buildings restrict permitted development in Northern Ireland.
Where in County Antrim do we work?
FAQ
Questions people ask
How long does a flat roof last?
A well-built single-ply or GRP warm roof typically lasts 25 years or more.
Is a flat roof really flat?
No; it is built to falls so water drains to outlets or gutters.
Can I walk on it?
Not as a balcony without planning permission and a guarding design; it can be accessed for maintenance.
Do you cover all of County Antrim?
We cover 7 towns and districts in County Antrim, including Belfast, Lisburn and Newtownabbey.
Who builds the extension?
Vetted building teams working under contract to us; your contract is with S&K Property Investments and Improvement Ltd.