The short answer
Low-pitch tiles are interlocking concrete tiles and clay pantiles whose makers publish a minimum pitch in the teens of degrees. In Marley's table the lowest are the Mendip 12.5 at 12.5 degrees, then the Mendip, Wessex and Lincoln clay pantile at 15. Anything shallower than the tile's stated minimum needs a continuous waterproof covering instead of tiles.
Why a low slope is hard on tiles
A tile roof sheds water by overlap, not by sealing. Each tile sits over the one below, and rain runs down the surface and across the joints. On a steep slope gravity does most of the work. On a shallow one the water moves slowly, and a strong wind can push it sideways or upwards under the laps, so water can travel further than the tile's design intended.
So every tile comes with a lowest slope that its maker will stand behind. The figure assumes the headlap, the underlay and the fixing are all as specified. Cross the line and the roof may look normal for a while, then fail in the first wet, windy spell. A low pitch leaves less room for error in the whole construction, not only in the tile itself.
The signs of a tile working below its limit are usually quiet ones: damp patches on the battens near the eaves, stained underlay, moss thick along the laps, or a ceiling mark that appears only in driving rain. Anything like that on a shallow roof is a reason to measure the pitch before blaming the tiles.
The Marley minimum pitch table
These figures come from Marley's guidance on the minimum pitch for roof tiles and slates. Always check the product's own data sheet for the exact tile and site.
| Tile | Type | Minimum pitch |
|---|---|---|
| Mendip 12.5 | Interlocking concrete | 12.5° |
| Mendip (smooth) | Interlocking concrete | 15° |
| Wessex | Interlocking concrete | 15° |
| Lincoln | Clay pantile | 15° |
| Edgemere, Modern and Duo (smooth) | Interlocking concrete | 17.5° |
| Double Roman, Ludlow Major, Ludlow Plus, Ashmore | Interlocking concrete | 22.5° |
The pattern is clear. Large, deeply profiled interlocking tiles manage the shallowest slopes. Plain tiles, which are small and rely on overlap alone, need at least 30 to 40 degrees on Marley's figures, so they are not low-pitch tiles at all.
Choosing between low-pitch options
When the pitch is low, the tile shortlist is short. A concrete interlocking tile gives the broadest choice of colours and the lowest minimum, and it is the usual answer on extensions, porches, bungalows and lean-to roofs. A clay pantile has the traditional S-shaped profile and suits houses where that look is part of the street. Our page on pantile roofs covers their faults and what to expect.
Matching the existing roof matters too. A low extension next to a steeper main roof often has to use a different tile from the main house, simply because the main-roof tile is not allowed at the lower angle. That is normal, and a good colour match makes it look intentional. Whatever you pick, sit comfortably above the minimum instead of exactly on it, because a roof that is only a degree or two over the line has no margin for exposed sites.
When a low pitch needs another covering
If the pitch is below the lowest tile, tiles are not the right answer. The covering has to be continuous: a rubber EPDM sheet or other single-ply membrane, a GRP fibreglass roof, lead or zinc sheet, or felt. Flat roofs rely on these, and they also serve a very shallow pitched roof. Natural slate is no help either, as the usual minimum for a 500 mm slate is 20 degrees, and hook fixings stop being an option below 25 degrees.
Even a nearly level roof needs a fall to drain. The code of practice, BS 6229:2018, recommends a finished minimum of 1:80, and designers aim for 1:40 to allow for building tolerances and deflection that would otherwise leave puddles. Ponding is the first fault to look for. If your roof sits right on the borderline, we measure it and tell you which side it falls on, and what that means for the covering.
Changing from tiles to a membrane is a substantial step, and the consent route depends on the work. The Planning Portal says a building control application is not normally needed for re-covering when less than 25 per cent of the total building envelope and less than 50 per cent of the roof is affected, and approval applies above those limits, so the scale of the job matters.
The parts around the tile
On a shallow roof the underlay, battens and flashings carry more of the weather load. A breathable underlay laid with correct drapes, batten sizes that match the tile, and lead flashing at abutments are all more important than on a steeper roof. Wind is the common enemy, and exposed locations such as a hilltop, an edge-of-town plot or a house with open fields beside it raise the stakes. Our page on tiles lifting in wind explains what happens when the fixing is not enough.
Ventilation changes at low pitches as well. Marley's guidance for BS 5250 asks for more eaves ventilation on pitches of 15 degrees or less than on steeper ones.
How we check your pitch
Our survey measures the real angle of each slope, reads the tile maker's data sheet and sets the two side by side. If a tile is working below its minimum, we explain whether re-laying with the right tile or a different covering is the sensible fix, and we favour the smaller job when it truly solves the fault. You are shown photographs of your own slopes, the price follows in writing, and the finished work is guaranteed for 10 years on paper.
For the wider picture of roof forms, see our guide to pitched roof types, or return to the pitched roofing hub.