What Is the Minimum Pitch for Roof Tiles?

A tiled roof sheds water by overlap, not by being sealed. Rain runs down the face of each tile and over the head of the one below. On a steep slope that is quick and sure. On a shallow slope water moves slowly and wind can push it uphill, so the laps have to be deeper or the tile shaped to resist it.

What decides a tile's minimum pitch?

The profile, the headlap and the exposure of the site. Headlap is how far each tile overlaps the course two rows down. A deep interlocking concrete tile with side channels can work at a lower angle than a flat plain tile. Marley states a minimum for each tile in its range and tells you to check the data sheet.

Pitch is measured in degrees from horizontal, and a roof that looks steep from the road may be only 30 degrees. Your roofer measures it on site, or from the drawings, before choosing a tile. If the pitch falls below the tile's limit, the choices are a different tile, a larger headlap if the maker allows one, or a different kind of covering altogether, such as a membrane. Guessing from the street is the one method that does not work.

These are Marley's published minimums (Marley, accessed Oct 2026). They are a guide and not a substitute for the data sheet for your tile.

What does smooth mean in that table?

Marley gives some minimums for the smooth finish, and a different figure may apply to other finishes of the same profile. A name alone is therefore not enough: check which tile and which finish you have, and read the sheet for that exact product.

The Double Roman has a Somerset connection through Bridgwater's tile works, and the modern concrete version carries the 22.5 degree minimum shown above.

Natural slate follows its own figures. The slate maker Cupa says BS 5534 indicates a minimum roof pitch of 20 degrees for natural slate. Below that angle a slate roof is a poor bet, however carefully it is laid.

Does slate pitch affect how slates are fixed?

Yes. Cupa adds that hook fixings are not suited to slopes under 25 degrees. A slate roof at 22 degrees might therefore take nailed slates but not hooked ones. When a single slate has to be replaced on a shallow slope, it is held at the tail by a metal strip nailed to the batten and folded over, in preference to a hook, a point covered in the answer on replacing a single slate.

Natural slate also needs a sensible headlap, and the lower the pitch, the more the fixing and the headlap matter. Exposure pushes the same way. A plan to slate a shallow extension roof should therefore be checked with the slate supplier before anything is ordered. If slate is the covering you want, our slate roofing page covers the work. Clay and concrete tiles follow the table above instead.

Measuring is cheap, and re-laying a failed roof is not.

You can estimate pitch from the ground with a phone app that measures angles, but a roofer's reading from a ladder or from the loft is better. In the loft, a protractor or pitch finder held against the edge of a rafter gives a clean figure, as long as you stay on the joists.

What if the roof is below the tile's minimum?

Do not fit the tile and hope. A tile used below its minimum can let water in during wind-driven rain, and the maker's warranty may be affected. The fix is a covering suited to the pitch, such as a lower-pitch tile from the table or a continuous membrane, or a change to the roof structure, which the answer on changing a flat roof to a pitched one looks at.

On an existing roof, the tiles already there were chosen for its pitch, so a like-for-like replacement is sensible. The roof tile profiles answer helps you identify yours, and the pitched roofing page covers the wider work. A survey records the pitch and the tile type, and you receive the photographs and the measurements. One written price then follows, based on what the survey finds.