Two-storey extensions for end-of-terrace houses in County Londonderry

County Londonderry at a glance

Nation: Northern Ireland
Price region: Northern Ireland
Postcode areas: BT
Towns covered: 11 listed below, plus surrounding villages
Approval route: Planning permission is needed: permitted development side extensions in Northern Ireland can't be more than 4 m high, which rules out two storeys.
Site visits: Free, no obligation

What a two-storey extension for an end-of-terrace house involves

This service suits you if you own an end-of-terrace house with land to the side or a reasonable rear garden.

Towns in County Londonderry include Derry (BT48), Coleraine (BT51), Limavady (BT49), Magherafelt (BT45), Portstewart (BT55) and Portrush (BT56). If yours isn't listed, we still cover it.

Guide price in Northern Ireland

Using our Northern Ireland rates, a two-storey extension for an end-of-terrace house with a 3 m × 7 m footprint on two floors (42 m² of new floor space) comes to about £76,000–£101,500, including VAT. Bigger or more glazed designs cost more per m². Design fees, structural calculations and approval fees are separate and listed on our prices page.

Spec	Per m²	Typical project
Essential	£1,660–£2,230 per m²	£69,500–£93,500
Standard	£1,800–£2,420 per m²	£76,000–£101,500
Premium	£2,160–£2,900 per m²	£91,000–£122,000

Rules in Northern Ireland

In Northern Ireland, a two-storey rear extension can be permitted development if it goes no more than 3 m beyond the original rear wall and stays 7 m from the rear boundary, with height, materials and roof pitch conditions. A two-storey side extension normally needs a planning application costing £347 per dwelling. There is no Party Wall Act.

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.

There is no Party Wall Act in Northern Ireland. Shared walls and boundaries are a matter of title and common law, so we agree access and record conditions with neighbours before work starts.

Getting the design right

Older walls and foundations

Many terraces are older, with shallow footings and solid walls. Tying a new two-storey extension into them needs a careful structural design and sometimes movement joints, and we check the gable wall and its foundations before the design is fixed.

Continuing the terrace roof

A side extension on an end-of-terrace house usually continues the roofline of the row, so the pitch, eaves height and tiles must match. A small step down in the ridge and a set-back at the front often help the extension read as an addition rather than an extra house.

How we work in County Londonderry

Visit and first ideas
One of our team visits your house in County Londonderry, checks the walls, roof and drains, and sketches out options with you.
Drawings and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering County Londonderry.
Technical design
We prepare the building regulations drawings, structural calculations and specification so the build price can be fixed.
Build and hand over
We manage the build from groundworks to decoration-ready finish and hand over with the completion paperwork.

Towns we cover in County Londonderry

Two-storey extensions for end-of-terrace houses in County Londonderry: questions

How much does a two-storey extension for an end-of-terrace house cost in County Londonderry?

In Northern Ireland our guide is £1,800–£2,420 per m² including VAT, so about £76,000–£101,500 for a 3 m × 7 m footprint on two floors (42 m² of new floor space). Essential and Premium specs move that by roughly 8% down or 20% up.

Can I build a two-storey side extension on a corner plot?

Often, but it needs planning permission and careful design. Councils protect the openness of corners and the view along the road, so they usually expect a gap to the pavement, a set-back from the front and a side wall with windows rather than a blank wall. We check local guidance and nearby examples first.

Are old terrace foundations strong enough to extend next to?

Usually, but they need checking. Older terraces often have shallow brick footings, and a new two-storey extension sits on deeper, modern foundations alongside them. The structural engineer designs the junction so the two can move slightly without cracking, and we dig trial holes to see what is there before the design is fixed.

Will my end-of-terrace extension look like a new house on the end?

It should not, if it is designed well. A slightly lower ridge, a set-back from the front wall and a different front door position help it read as an extension. Councils often ask for this to avoid an extension that looks like an extra terraced house.

Will I need planning permission in County Londonderry?

County Londonderry is in Northern Ireland. Planning permission is needed: permitted development side extensions in Northern Ireland can't be more than 4 m high, which rules out two storeys.

Neighbouring areas

All extension services in County Londonderry · About two-storey extensions for end-of-terrace houses