Minimum pitch for a metal roof: what each type needs

The minimum pitch depends on the roof covering: BELPROFILE metal roof tiles need at least 14°, click roofing sheets at least 12°, and standing seam roofing is also installed on low pitches, from 3.5°. Below the minimum pitch, water runs off too slowly and can get through at the joints. For a mono-pitch roof, which usually has a low pitch, the choice is standing seam roofing.

The minimum pitch, by type of roofing sheet

How do you convert degrees to a percentage?

The percentage shows how many centimetres the roof rises for every metre measured horizontally. A pitch of 25% rises 25 cm over one metre and means 14°. A pitch of 100% rises one metre over one metre and means 45°. The pitch is written either in degrees or as a percentage: check which of the two yours is written in.

What is the minimum pitch of a mono-pitch roof?

A mono-pitch roof has a single roof slope and, most of the time, a low pitch. The roof covering is chosen by its pitch:

• from 14° upwards: any of them, including metal roof tiles;
• between 12° and 14°: click roofing sheets or standing seam roofing;
• below 12°: standing seam roofing.

Why does standing seam roofing work on low pitches?

Because it has no crosswise joints and no holes. The panels run in one piece from the eaves to the ridge, up to 12 m, and are closed to one another by a seam. On low pitches a double lock seam is made: the installation principles require it from 5° upwards, and below this pitch special sealing elements are added. The single lock seam is used only from 25°.

What happens below the minimum pitch?

Water stays on the roof longer, and the wind can push it back under the overlaps. Snow melts slowly and its water rises at the joints. A roof installed below the minimum pitch of its roof covering can leak even if the sheets are good.

And the slope of the gutter?

The gutter has a slope too, towards the downpipe: when the gutter brackets are marked out, 2.5–5 mm are allowed for every metre of eaves.

In short

14° for metal roof tiles, 12° for click roofing sheets, from 3.5° for standing seam roofing, between 22° and 45° for metal shingles. Measure the pitch before you choose the roof covering, not after. If you are not sure what fits, request a quote with the roof plan: the advice is free.