The short answer
Usually not, if the new roof looks the same as the old one. Under section 55 of the Town and Country Planning Act 1990, work that leaves a building's outside appearance materially unchanged is not development, so a like-for-like covering needs no application. Raising the roof, adding a parapet or changing its look is a question for the council.
Swapping one flat roof covering for another is routine. Planning only becomes a live question when the roof changes shape, height or appearance, or the building is protected.
Like-for-like work is not development
Planning permission is needed for development, and the law defines that word. Section 55(2)(a) of the Town and Country Planning Act 1990 excludes work which leaves the exterior looking materially the same as before. Stripping a worn felt or rubber covering and laying a new one at the same height and with the same outline sits comfortably inside that wording. The rule looks at appearance, not at the material underneath.
What about a different covering?
Class C of Schedule 2, Part 1 of the General Permitted Development Order 2015 is the national rule covering roof alterations to a house, and re-roofing is one of them. A change from felt to EPDM, a synthetic rubber sheet, or to GRP, glass-reinforced plastic, is normally permitted development on a house. That phrase means national rules already grant permission, so nobody files an application.
Flats are treated differently. The Order excludes a building containing flats, and a single flat inside one, from the meaning of dwellinghouse. If the roof belongs to a flat, ring Somerset Council's planning team first, and only then place an order for materials.
When to ask the council first
Some jobs go beyond swapping a covering. Whenever the finished roof would look different from the street or a neighbour's window, the sensible move is a quick conversation with the council, ahead of buying anything. That costs nothing and avoids a roof that has to come off again.
Does raising the roof height need permission?
It can. Under Class C.1(b), an alteration that protrudes more than 0.15 metres past the original roof surface falls outside permitted development. A deep build-up of insulation, a new parapet wall or a taller edge detail can cross that line. Thicker insulation is the usual cause. The survey tells you how far the finished surface will rise, measured against the walls, windows and doors around it.
Adding a rooflight, fitting railings to make a terrace, or building a kerb for a lantern also changes the outline or the use of the roof. A short email to the planning team at Somerset Council, with a sketch and a description, usually gets a clear reply. For a house inside Exmoor National Park, ask Exmoor National Park Authority, which holds the planning role there.
Our page on flat roof Building Regulations covers the separate insulation and fire rules, which apply whatever planning says. The wider range of work is on the flat roofing page.
Conservation areas and listed buildings
Protected buildings add a second layer of consent, and the two layers work differently.
Does a listed building need consent for a flat roof?
If the work affects its character, yes. Listed houses keep their Class B and Class C permitted development rights, but they also need listed building consent for works that alter the building in a manner that touches its special interest (Planning (Listed Buildings and Conservation Areas) Act 1990, section 7). A flat roof over an old extension, a lead-covered porch or a roof tucked behind a parapet may all count. Ask before anything is stripped.
What changes in a conservation area?
A conservation area is Article 2(3) land. Class C has no exclusion for it, so a like-for-like covering on a house normally remains permitted development, whereas dormers do not. An Article 4 direction can take rights away locally; Somerset Council lists them for places such as Staplegrove Road in Taunton, and the planning team confirms what each one covers. The Quantock Hills, Blackdown Hills and Mendip Hills National Landscapes bring the same dormer limit. See flat roofs in conservation areas for more.
Planning is not the only permission
People often ask about planning when the rule that bites is a different one. Building Regulations are a separate system, and a flat roof replacement can trigger them even when planning is not involved at all.
Who checks the Building Regulations side?
Approved Document L treats a fresh membrane laid on a flat roof as renovation, so the insulation standard comes into play. The Planning Portal's re-roofing test asks two things: is less than 25 per cent of the building envelope affected, and is less than 50 per cent of the roof affected? A whole new roof over an extension or garage affects all of its own roof, so building control is normally involved. In Taunton that means Somerset Building Control, on 0300 303 7790.
Working out which consents apply is part of the survey. If the council does need asking, we raise it with you before any start date is agreed, because a refusal or a delay is cheaper to learn about early. Our answer on insulating a flat roof when replacing it explains the energy side, and the written price comes after the scope is settled.
More on flat roofs and consent
Do I need a certificate to prove a flat roof was allowed?
For planning, a like-for-like replacement leaves nothing to certify. For Building Regulations, a notifiable job should end with a completion certificate from the building control body, and Somerset Building Control keeps copies of them for 15 years. A buyer's solicitor often asks for it, so file it with the house papers.
Can a rooflight be added when the flat roof is renewed?
Often yes, but it is an alteration, so the same questions apply: how it looks from outside, whether it is a listed building or inside a conservation area, and the Approved Document L figure for a rooflight (2.2 W/m²K). Decide before the covering goes down, because cutting in later means opening up a brand new roof.
The full picture: Flat roofing in Taunton · More short answers