- Guide price
- £2,450–£4,300
- Survey
- Free for new and replacement roofs
- Quote
- Fixed, in writing
- Coverage
- England, Wales, Scotland, NI
County Down at a glance
- Largest towns
- Bangor, Newtownards, Newry, Banbridge
- Postcode areas
- BT
- Building control
- Ards and North Down Borough Council, Newry, Mourne and Down District Council, Armagh City, Banbridge and Craigavon Borough Council and 1 other council
- Neighbouring areas
- Belfast · County Antrim · County Armagh · County Tyrone
- Guide price region
- Northern Ireland (−12% on West Midlands rates)
How much does a new extension roof cost in County Down?
Guide prices including VAT at Northern Ireland rates. The fixed price comes after a free survey for new and replacement roofs.
| Job | Guide price inc VAT |
|---|---|
| Extension (20 m²), EPDM, new deck + insulation | £2,450–£4,300 |
| Extension (20 m²), GRP, new deck + insulation | £2,650–£4,750 |
| Extension (20 m²), EPDM, insulation + 1 rooflight upstand | £2,650–£4,600 |
| Single garage (18 m²), EPDM rubber | £1,400–£2,450 |
Which flat roofs are common in County Down?
Flat roofs in County Down sit on shops with flat-roofed rear stores below flats, 1960s and 1970s link-detached houses with flat-roofed garages and porches and lock-up garage blocks on estates. Northern Ireland averages roughly 1,150 mm of rain a year, spread over many wet days, so a roof that sheds water quickly to clear outlets lasts far longer than one that holds puddles. Approximate 1991–2020 regional averages based on Met Office data.
Building control in Northern Ireland
In Northern Ireland, renovating or replacing a roof over a heated room usually means meeting Technical Booklet F1, and building control should be contacted before work starts. Technical Booklet F1 sets roof insulation at 0.18 W/m²K when a roof over a heated room is renovated or newly built, where feasible. In County Down the application goes to Ards and North Down Borough Council, Newry, Mourne and Down District Council, Armagh City, Banbridge and Craigavon Borough Council and 1 other council. More on the rules.
Which flat roof system suits a kitchen extension?
On a plain rectangular extension, EPDM rubber is a strong, quiet choice that can often be laid in one sheet. It handles the slight movement between an extension and the house well.
Where the roof has a lantern, several rooflights or an internal corner, GRP fibreglass forms neat, rigid details around each one. Torch-on felt is a proven layered system and keeps costs down, though near timber cladding or at fragile junctions we may prefer a cold-applied method. If the extension is overlooked from upstairs windows, a sedum green roof is worth considering, provided the structure can take the extra load.
Whatever the membrane, the insulation sits above the deck as a warm roof. Our warm vs cold roof guide explains why.
Which towns in County Down do we cover?
- Bangor
- Newtownards
- Newry
- Banbridge
- Dundonald
- Holywood
- Downpatrick
- Comber
- Carryduff
- Warrenpoint
- Newcastle
- Donaghadee
Extension and kitchen roofs in County Down: questions
Which towns in County Down do you cover?
All of County Down. The main towns have their own pages below, and if yours isn't listed we still cover it: send your postcode and we'll confirm.
How much does a new extension roof cost in County Down?
£2,450–£4,300 for a 20 m² extension roof in EPDM with a new deck and insulation, at Northern Ireland guide rates including VAT. The fixed price comes after a free survey for new and replacement roofs.
Which postcode areas do you cover in County Down?
All of County Down, including the BT postcode areas. Send your full postcode and we'll confirm.
Can a sedum roof go on my extension?
Possibly, if the structure can carry the extra weight and the roof has suitable falls and drainage. We check the joists at survey before recommending it.
How do I know my extension roof needs replacing rather than repairing?
Repeated leaks, a soft deck, wet insulation or widespread cracking point to replacement. A single defect on a dry, sound roof can usually be repaired.
Why does my extension ceiling get damp in winter if the roof isn't leaking?
That is often condensation in a cold roof, where warm, moist air reaches the cold underside of the deck. A warm-roof replacement with a vapour control layer usually solves it.
Everything about extension and kitchen roofs → · All flat roofing in County Down →