The short answer
Not always. Planning law treats work that leaves a building's outward look materially unchanged as falling outside development, so a like-for-like replacement may need no permission. A change of material, colour, profile or height, or new rooflights, can alter the look. The householder rights for houses do not cover commercial buildings, so put the question to Somerset Council's planning team before you commit.
Re-covering a shop, unit or barn is often straightforward, but the planning rules differ from those for a house. The question is whether the building looks different afterwards.
The appearance test
The Town and Country Planning Act 1990, in section 55(2)(a), says that maintenance, improvement or alteration of a building is not development if it leaves the external appearance materially unchanged. That sentence is where every commercial roof question starts, and the rest of this page follows from it. Nothing in it mentions cost or size, only the look of the finished building.
What counts as materially different?
The word is a matter of judgment, and the planning authority makes that judgment. Swapping like for like, with the same profile, a very close colour and the same height, is the clearest case of no material change. Moving from clay pantiles to flat metal sheets, from natural slate to a profiled steel sheet, or raising the ridge to gain headroom is a change someone will want to look at.
Added features matter too. New rooflights, plant, flues or solar panels alter what a passer-by sees on the skyline. Where the building sits somewhere its outward appearance is already protected, the answer gets more cautious again, and the third section below covers those places. A rear roof hidden from every public view is still part of the building, so do not assume it is exempt.
Why the house rules do not apply
People often quote permitted development for roofs, and that sentence is about houses. Class C of Part 1, Schedule 2 of the General Permitted Development Order is headed by roof alterations to a dwellinghouse, and in the Order that word leaves out any building containing flats.
So what applies to a shop or unit?
The householder class is not available. That does not mean permission is needed for a roof replacement. It means the appearance test above does the work, and any other permitted development right for a particular type of building has to be checked on its own terms. Agricultural, industrial and retail buildings each have separate rules that lie outside what we advise on.
The practical step is to describe your project to Somerset Council's planning team and ask directly. A short enquiry with photographs of the building and a note of the new covering gets to the point faster than a long exchange of letters. We supply that detail from the survey, including the existing profile and colour, so the enquiry is specific from the first email.
Places where the answer changes
Some buildings carry extra protection, and a roof is among the first things to change how they look.
What changes for a listed building or a conservation area?
A listed building needs listed building consent for any alteration that would touch its special architectural or historic character, and a roof forms a large share of that appearance. A conservation area, designated by the council, adds scrutiny to changes anyone can see from a public road. Somerset Council keeps a table of Taunton's conservation areas with their designation dates, and an Article 4 direction, which withdraws permitted development rights in a defined area, is listed for some places in the former Taunton area. What any particular direction covers is something to put to the planning team, which holds the notices.
Inside Exmoor National Park, planning decisions sit with Exmoor National Park Authority and not with Somerset Council. Church and chapel buildings follow their own consent routes, and a scheduled monument needs scheduled monument consent. In every case, ask before ordering materials.
How to ask, and what we do
A planning enquiry costs little time, and a wrong assumption can cost a roof. Ask Somerset Council's planning team, or Exmoor National Park Authority inside the Park, whether permission is needed for your exact change.
What do you need for the enquiry?
Send the building's address, its use, the existing covering and the proposed one, any change in height or rooflights, and photographs. Ask for the council's reply by email or letter and file it with the building's deeds and maintenance records, so a later owner or buyer's solicitor can find it. A formal route exists for getting a legally binding answer, and the planning team can explain it.
On our side, the survey records the existing covering, profile and colour with photographs, and the written price is fixed as one total after the survey. Related reading: Building Regulations for commercial re-roofing, roof overcladding and insulated roof panels, within our commercial roofing service. Start by sending the address and the covering you have in mind.
More on commercial roof planning
Does a colour change count as a material change?
It can. A colour that stands out against its surroundings changes the look from the road, and a planning authority may treat that as material. A near match for the old covering is safer. If you want a different colour, send the planning team a photo of the building and a sample, and ask before you order.
Are extra rooflights in a replacement commercial roof a planning matter?
Adding rooflights changes the roof's appearance, so put it to the planning team whether the building is a unit, a barn or a shop. Replacing existing rooflights in the same positions is a smaller change. Either way, tell us during the survey so the positions and sizes are in the plan you take to the council.
The full picture: Commercial roofing in Taunton ยท More short answers