- Guide price
- £2,450–£4,300
- Survey
- Free for new and replacement roofs
- Quote
- Fixed, in writing
- Coverage
- England, Wales, Scotland, NI
Belfast at a glance
- Largest towns
- Belfast
- Postcode areas
- BT
- Building control
- Belfast City Council
- Neighbouring areas
- County Down · County Antrim · County Armagh · County Tyrone
- Guide price region
- Northern Ireland (−12% on West Midlands rates)
How much does a warm roof upgrade cost in Belfast?
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), EPDM with sedum green roof | £3,900–£7,100 |
Which flat roofs are common in Belfast?
Flat roofs in Belfast sit on lock-up garage blocks on estates, 1960s and 1970s link-detached houses with flat-roofed garages and porches and terraced streets with flat-roofed rear kitchens and bathrooms. 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 Belfast the application goes to Belfast City Council. More on the rules.
How long does a warm roof last?
The insulation in a warm roof should last for the life of the waterproofing above it, as long as it stays dry. Rigid PIR boards don't settle or slump in the way some loose insulation can.
The waterproofing is what sets the timescale. EPDM is typically quoted at 25 to 50 years, GRP at 20 to 40 years and modern torch-on felt at 15 to 25 years with good specification and care. A warm build-up also helps the deck, because keeping it warm and dry lowers the risk of condensation rot. If the waterproofing fails and water gets into the insulation, the wet boards should be replaced, so leaks need prompt attention. The lifespan guide compares the systems.
Can a cold flat roof be converted to a warm roof?
Yes, and it is the usual approach when an older cold roof is re-covered. The old covering is stripped, the deck is checked and replaced where needed, and the vapour control layer, insulation and new waterproofing go on top.
The existing insulation between the joists is assessed at the same time. Leaving it in place can create a cold, unventilated gap that traps moisture, so it is often removed or the build-up is designed so that most of the insulation sits above the deck. We decide this case by case once we can see inside the roof. If the covering is still sound and you are only patching it, the upgrade isn't usually required, and our repair or replace guide explains how to decide between the two.
Which towns in Belfast do we cover?
Warm roof insulation upgrades in Belfast: questions
Which towns in Belfast do you cover?
All of Belfast. 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 warm roof upgrade cost in Belfast?
£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 council handles building control for a flat roof in Belfast?
It depends on where the roof is: in Belfast that's Belfast City Council. 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. We confirm which applies at the survey.
Does a warm roof stop condensation?
It greatly reduces the risk by keeping the deck warm and placing a vapour control layer on the warm side. Good ventilation in kitchens and bathrooms below still helps.
Is a warm roof worth it on a garage?
On a detached, unheated garage, usually not, as there is no heated space to protect and the thermal rules don't normally apply. On an integral or heated garage, or one being converted into a room, it is.
Will a warm roof make my room warmer?
Usually, yes. A room under a poorly insulated flat roof loses less heat once the roof is upgraded and tends to feel more even in temperature. How much difference you notice depends on how the roof was built before.
Everything about warm roof insulation upgrades → · All flat roofing in Belfast →