Commercial roofing in Bognor Regis

A flat roof is never truly flat: it needs a fall to the outlets, a sound deck and a covering matched to the building.

Flat roofs sit over the rear extension of a shop, the workshop unit, the small office building and the top floor of a block of flats. Failure tends to follow a pattern. Old felt splits and blisters, laps open at the edges, and an upstand, the short vertical return where the covering climbs a wall or parapet, peels away. Outlets silt up with grit, so rain stands where it ought to drain. Because a commercial flat roof can cover a wide area, and the rooms beneath it are in daily use, one small fault can send water into a suspended ceiling, a stockroom or the flat below before anyone notices a mark from outside.

1.1 Felt, EPDM and GRP on a commercial roof

Built-up felt is bitumen sheet melted onto the deck by gas flame, in layers. The guide site Less, updated March 2026, quotes 10 to 20 years for it and adds that a poorly laid roof might fail within ten. EPDM is a rubber membrane supplied as a single sheet, with an expected service life of 20 to 30 years according to GreenSpec. GRP, short for glass-reinforced plastic and better known as fibreglass, is laid as a resin laminate, and Less puts it at 25 to 40 years. A repair has to use the same family of material as the covering around it, since a felt patch will not bond to rubber or resin. Our guide to commercial flat roof systems compares the three, and the page on built-up felt explains why the older system still turns up on buildings today. A roofing solution that suits one building rarely suits the next, so the covering is chosen to suit the building, its foot traffic and the budget, never because it is what we happened to have in stock.

1.2 Falls, ponding and the deck underneath

Pools that linger after rain mean the roof was laid with too little fall, the gentle gradient that sends water to the outlets. BS 6229:2025, current since December 2025, sets a minimum finished fall of 1:80, and designers normally aim nearer 1:40 so that the roof still drains after the structure has moved a little. When ponding spreads across the middle, patching the low spot rarely holds, and tapered firring strips may have to go under a new covering to create the gradient. Beneath the membrane, the deck matters just as much. Soft boards or damp insulation turn a patch into a short-term fix at best. We press, probe and photograph before we say which situation you have, and the plain verdict names it. For the replacement work in full, see our flat roofing service.

Offices, flats and halls often sit under tile or slate, and the ridges, edges and lead are where those roofs let go.

Not every commercial roof is flat. Offices in converted houses, the floors above a row of shops, blocks of flats, halls and some older workshops sit under pitched roofs of tile or slate. The repair logic matches a house, with two differences: the roof is usually bigger and higher, and access costs more. A scaffold or a tower often earns its place because it lets the work be done properly in one visit instead of being patched from a ladder.

3.1 Tile, slate and the fixings that hold them

Catch a slipped or cracked tile early and the fix is modest. Tiles hang on timber battens, and slipping usually traces back to a snapped nail, a broken nib or a batten gone soft. Slate has a habit of its own: once the nails holding the slates have rusted through, slates slide down a whole slope, and replacing them singly stops making sense. When a re-roof is justified, the new roof covering can be tile, slate or another material, and the choice should suit the building, the street and the budget, and the survey says which materials the structure can carry. Marley expects concrete tiles to last around 60 years but is clear that this is not a guarantee or warranty of longevity, while the Confederation of Roofing Contractors puts well-maintained slate at 100 years or more.

3.2 Ridges, verges and exposure

At the apex runs the ridge, hips are the sloping outer corners of a hipped roof, and a verge is the sloping edge where tiles end at a gable wall. These are the places the wind attacks first. Under BS 5534, the British Standard for slating and tiling, revised in 2014, ridge and hip tiles are held by mechanical fixings as well as their mortar bed, which is how we fix them. Marley warns that on pitches under 30 degrees the windward slope can suffer severe suction, a point that counts for low-pitched roofs near the sea. Sea weather, gales and driving rain work on every edge, and a dry-fixed ridge or verge tested to BS 8612:2018 is one answer on an exposed gable. Whatever is chosen, the workmanship matters as much as the product, because a good tile badly fixed lets go in the first strong gale.

3.3 Matching materials on older buildings

Commercial buildings in Bognor's conservation areas can keep original slate or clay tile. Where a repair involves two materials, we match the colour, size and laying pattern so the roof still reads as a single roof from the street.

There is no single price for a commercial roof, because area, access and covering vary widely from one building to the next.

Search for a price and you will find domestic cost guides, not commercial ones. That is because commercial roofs differ too much to share a rate: a single-storey shop extension and a three-storey block of flats have little in common beyond the word roof. What moves the price is the same list on every job, and knowing it helps you read any quote you are given, ours included.

5.1 What sets the price

Area comes first, then height and access, because work slows wherever the roof is hard to reach. Next is the covering and its quality, because material choice sets both the first cost and the years you can expect from it: felt, EPDM, GRP, slate and clay tile all differ in what they cost to supply and fix. Then comes whatever the survey finds once the roof is opened up, such as wet insulation or a soft deck. Working hours matter too. A job planned around trading hours, or squeezed into short winter days, takes longer than one done in a clear week, and a roof that must stay in use throughout needs more careful phasing. Checkatrade gives roofers' rates as around £35 to £45 an hour or £280 to £360 a day, which is why a one-day patch and a two-week re-roof sit so far apart. The standard rate of VAT is 20 per cent, so check whether any quote you receive includes it.

5.2 Scaffold, access and licences

Checkatrade's scaffolding guide, table updated October 2026, lists about £875 a month for a semi-detached house of two storeys and about £1,000 for a detached bungalow. A commercial frontage can need a different set-up altogether. If the scaffold sits over the footway or carriageway, a licence from the highway authority is needed under the Highways Act. West Sussex County Council asks for at least 10 working days' notice and charges £266 for one month, and Hampshire County Council, which covers Havant, asks for ten clear working days. That lead time belongs in your plan before a start date is fixed.

5.3 Reading a commercial quote

Check what the one total covers: scaffold, waste removal, VAT and any insulation work. Ask who stands behind the workmanship, for how long, and whether that is in writing, and whether a membrane carries a manufacturer's warranty on top. A warranty is not a lifespan. Our guide to commercial roof replacement costs goes into more detail.