Extra bedroom and en-suite extensions in Crumlin (County Antrim)

Before you start in Crumlin (County Antrim), here's what applies.

Postcode districts: BT29
County / area: County Antrim, Northern Ireland
Price region: Northern Ireland
Guide price: £49,500–£66,500 (£1,760–£2,380 per m²), plus £5,500–£11,000 for the en-suite
Approval route: It may be permitted development if it goes no more than 3 m beyond the original rear wall and stays 7 m from the rear boundary.
Nearest towns: Antrim (6.7 miles), Randalstown (9.6 miles), Moira (9.7 miles)
Distance to Belfast: about 11.7 miles
First visit: Free, no obligation

About an extra bedroom and en-suite extension

An extra bedroom and en-suite extension is a two-storey extension planned around a new double bedroom with its own shower room on the first floor, with a ground-floor room below. It is one of the most effective ways to add space for a growing family. Nationwide's 2025 research linked adding a double bedroom and bathroom to a three-bed, one-bathroom house with value gains of up to 24%.

Around Crumlin (County Antrim) we also work in Antrim, Randalstown and Moira, and across the rest of County Antrim. Postcode district in and near Crumlin (County Antrim): BT29.

What it costs in Crumlin (County Antrim)

Our guide for Northern Ireland is £1,760–£2,380 per m² including VAT. On a project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space), that puts an extra bedroom and en-suite extension in Crumlin (County Antrim) at roughly £49,500–£66,500 (plus £5,500–£11,000 for the en-suite). Kitchens, bathroom fittings and flooring are priced separately so you can compare like with like.

Spec	Per m²	A 4 m × 3.5 m footprint on two floors (28 m² of new floor space)
Essential	£1,620–£2,190 per m²	£45,500–£61,000
Standard	£1,760–£2,380 per m²	£49,500–£66,500
Premium	£2,110–£2,850 per m²	£59,000–£80,000

Planning and building control in Crumlin (County Antrim)

In Northern Ireland, a rear extra bedroom extension can be permitted development within 3 m of the original rear wall and 7 m from the rear boundary. Upper side windows within 15 m of a neighbouring boundary must be obscure-glazed and non-opening. Other designs need a planning application costing £347, plus building control approval.

Approval in Northern Ireland: Planning application for works to a house: £347. Councils aim to decide local applications within an average of 15 weeks; many take longer.

Building control: Building control approval from the local council under the Building Regulations (Northern Ireland), using the Technical Booklets.

Design points for Crumlin (County Antrim) homes

Connecting to the landing

The new bedroom must be reached from the existing landing, usually through a new opening in the outside wall or by taking part of an existing bedroom as a corridor. We look at the stairs and landing first, because a poor connection can waste much of the new space.

Sound and privacy

Bedrooms above a kitchen or family room benefit from an insulated floor to reduce noise. Side-facing upstairs windows usually have to be obscure-glazed, so we place the main bedroom window to the rear and the en-suite window to the side where possible.

How we'd run your project

Look at the house
We start in Crumlin (County Antrim) with a free visit: measurements, photos, a look at the loft and drains, and a frank chat about budget.
Drawings, then consent
We draw the scheme, check it against the rules in Northern Ireland, and take it through the right consent with the council.
Fixed price in writing
With approved drawings and calculations, we give you a fixed build price and a programme you can plan around.
Build and sign-off
Vetted teams working under S&K build the extension, and we arrange the building control completion certificate at the end.

Questions about extra bedroom and en-suite extensions in Crumlin (County Antrim)

Who handles building control for a project in Crumlin (County Antrim)?

We handle it as part of the project. What's needed in Northern Ireland: building control approval from the local council under the Building Regulations (Northern Ireland), using the Technical Booklets. We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.

Do I need planning permission for an extra bedroom and en-suite extension in Crumlin (County Antrim)?

Crumlin (County Antrim) is in Northern Ireland. It may be permitted development if it goes no more than 3 m beyond the original rear wall and stays 7 m from the rear boundary.

How long does an extra bedroom and en-suite extension take?

Allow 4 to 8 weeks for survey and design, then the approval period (councils aim to decide local applications within an average of 15 weeks; many take longer), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.

Does an extra bedroom add value to my house?

It usually does, though not always by the full cost. Nationwide's 2025 research found that adding a double bedroom to a two-bed house was linked to about 13% higher value, and a double bedroom and bathroom on a three-bed, one-bathroom house up to 24%. Local ceiling prices still apply.

What goes on the ground floor below a new bedroom?

Whatever suits you: a bigger kitchen, a family room, a study, a utility or a downstairs shower room. The ground floor usually costs about the same whatever it is used for, apart from kitchen units and bathroom fittings, which are priced separately.

Nearby

Close to Crumlin (County Antrim)? We work across the area, including:

Other extensions in Crumlin (County Antrim)

All two-storey extension services in Crumlin (County Antrim) · Extra bedroom and en-suite extensions across County Antrim

Book a free site visit in Crumlin (County Antrim) and we'll tell you what's possible, what approvals you need and what the design stage would cost.