Question answered
Shop flat roof repairs
The short answer
A shop flat roof leak is traced to its source first, because the mark inside is seldom beneath the fault. Typical repairs are patches, renewed upstands or outlet work, while a worn-out membrane needs re-covering. In a mixed-use building, check who owns and maintains the roof under the leases, and ask building control which rules apply to the flats above.
A flat roof over a shop often serves more than one party: the shopkeeper below, perhaps flats above, and a landlord. Finding the leak and sorting out responsibility are as much a part of the job as the repair.
Where shop roofs leak
Most shop flat roofs are asphalt, felt, single-ply or a liquid-applied covering over a deck, with parapet walls on the street side and a rear upstand against the next building. The faults repeat. Water gets in where the membrane meets the parapet, around rooflights and pipes, at outlets blocked by leaves and litter, and wherever the covering has blistered or split.
Ponding is a clue. Water that stays on the surface a day or two after rain means the falls are poor or the deck has sagged. For a new or refurbished flat roof, IKO, citing the 2018 edition of BS 6229 (since revised), gives a recommended minimum fall of 1:80 and says to design to 1:40 to allow for tolerances.
Inside, the stain on the ceiling may be several metres from the hole, because water runs along the deck or a joist before it drips. We follow the marks back to the cause before pricing anything, and the photographs you receive show your own roof.
Repair or renew
A fault in one spot justifies a repair in one spot, such as a patch, a renewed upstand or a new outlet. Repeated patching, widespread blistering or a deck that feels soft underfoot points towards re-covering. MyBuilder puts a flat roof's typical life at 15 to 30 years, depending on the material, so age helps decide.
Approved Document L Vol 1 lists replacement of a dwelling's whole flat roof waterproofing as renovation of a thermal element, which can bring a requirement to upgrade the insulation too. Where the flats sit above the shop, ask building control which volume of Part L applies to the mixed building rather than guessing.
Our guidance on commercial flat roof refurbishment explains the options for a full renewal, and the commercial roof cost page covers what moves the price. The written quote follows our survey.
Flats above the shop
A parade of shops with flats over them raises questions about ownership. Often one freeholder owns the building and grants leases, and the roof may be shared between lessees through a service charge. Read the leases, or ask the managing agent, to find out who is responsible for the roof and who instructs the work. Do not start without that answer, or you risk paying for work on a roof that is not yours.
Planning rights differ too. The householder rights in Class C of the General Permitted Development Order are for a dwellinghouse, a term the Order defines so as to leave out any block with flats in it and any flat inside one. A flat over a shop therefore cannot lean on those rights for roof alterations, so ask the Adur & Worthing planners before you change how the roof looks.
Mending a roof with the same materials seldom calls for planning permission, though listed buildings and Article 4 areas carry their own caveats. The leaseholders below, and the shop beneath, should all be told before work starts.
Access, scaffolding and trading hours
A flat roof over a shop has no side access, so the route is either the stairs, an external ladder, or scaffolding from the street. Where scaffolding stands on the footway, the scaffold firm applies to the highway authority for a licence under section 169 of the Highways Act 1980. Across Worthing and Adur the county council is the highway authority, and it asks for a minimum of 10 working days' notice.
That lead time matters when the leak is live. With an active leak, the first visit is about stopping the water, and the permanent repair is then planned around the licence.
Shops have to open. Pavement hoarding, deliveries and customer entrances all need planning, and our page on roof work while the business stays open deals with that in detail. With an older parade, ask about asbestos in the roof: HSE's starting point is that a pre-2000 building may contain it, and a survey should settle the question.
Tell the neighbours with a party wall or a shared parapet before work begins, too.
Before you instruct anyone
Photographs of the roof surface, the parapet, the outlets and the underside of the deck show the problem more clearly than any description. Keep a dated record of leaks, with the weather that day, because it helps trace the cause and supports a landlord or insurer discussion.
Ask the contractor what the quote covers: the scaffold, the repair, the waste and whether VAT is included. You receive the quote in writing with a single total, which a managing agent can approve in one go.
If a metal canopy or corrugated section is part of the building, see liquid coatings for metal roofs. At the end of a tenancy, repair duties also arise; roof dilapidations at the end of a lease sets out the practical steps. For churches and halls with similar flat extensions, see church and village hall roof repairs. All of it sits within our commercial roofing work.
Roofs over shops: two more questions
Can the roof be repaired from inside the shop?
Rarely. A repair works on the weather side of the deck, and the inside can show only where water emerges. Getting into the ceiling void helps a survey, because tide marks and wet timber point to the entry point, but the fix is made from the roof.
Do I need a new roof if the lease says I repair it?
Not necessarily. A repairing lease asks you to keep the roof in repair, which a sound patch can satisfy, while a re-cover is a larger decision. Show your landlord's agent the survey photographs and written quote before choosing, and take advice on the lease wording from a solicitor.
Tell us about your roof
Describe what is happening and we will call you back to arrange a visit.
- Photographs of what we find
- A written quote with one total price
- Or call 01903 299063
10-year workmanship guarantee, in writing.