UK Minimum Roof Pitch: What Approved Document C Doesn't Set

The requirement

Here’s the honest answer: Approved Document C sets no minimum roof pitch at all. Not for tile, not for slate, not for sheet roofing. There is no clause or table to cite for the flattest you can lay. The real numbers come from BS 5534 and your roofing maker’s own data sheet.

Approved Document C is the guide to Part C of the Building Regulations 2010. Its full title is “Site preparation and resistance to contaminants and moisture”. It covers ground damp under the slab, damp in outside walls, and roofs keeping the weather out in general terms. A full search of the current document finds one pitch figure, and it is not a minimum. One stray insulation rule treats a roof pitched at 70 degrees or steeper as a wall. That rule is not about pitch. That is its only pitch number.

What Approved Document C covers	What it doesn’t cover
Ground moisture and contaminants below a solid floor	A minimum pitch for tile, slate or sheet roofing
Moisture resistance of external walls and cladding	Product-specific pitch/exposure limits
Roof weathertightness, as a general performance outcome	Fixing specifications for any roofing material

So you may have heard “the regs say” a certain pitch for slate or interlocking tile in England or Wales. That number is not from Approved Document C. It comes from a standard this page can name, but not reprint.

Where the actual numbers live

BS 5534 sets minimum roof pitch for tiled and slated roofs in the UK. Its full name is “Slating and tiling for pitched roofs and vertical cladding”. It sets the minimum by material, tile or slate size, exposure zone, and fixing method. It is a paid British Standard from BSI, not free text. The same goes for BS 5385-1 in wet rooms, and for AS 2050 in Australia. This page cannot quote its figures without a licence.

Your roofing maker also declares its own minimum pitch for the exact tile, slate or sheet you lay. That figure is often stricter than the general BS 5534 one for that class of product. Approved Document C accepts BS 5534 and the maker’s data as a route to meeting the Building Regulations. But it never states those numbers itself.

What this means on site

There is no Approved Document C clause to build to. So follow the standard and the product, not a page number:

Get the current BS 5534 if you design or specify a roof. Buy it through BSI or your trade body. It sets minimum pitch by material, exposure zone and fixing method. Do not trust a secondhand summary for the design detail.
Check the maker’s data sheet for the exact tile, slate or sheet you lay. A building control surveyor checks your roof against that declared minimum pitch, since there is no Building Regs clause. It can be stricter than the general BS 5534 figure.
Match the exposure zone. BS 5534 and most maker specs adjust the minimum pitch and the fixing spec for wind. A coastal or hilltop site can need a steeper minimum, or extra fixing, than a sheltered inland site with the same product.
Keep the paperwork. With no clause to cite, your proof is the standard you followed, the maker’s data sheet, and a record that you laid it as specified.

UK building regulations hub: how the code works across England, Wales, Scotland and Northern Ireland.
UK wet-area waterproofing: what Approved Document C doesn’t cover: another case where the real numbers live in a paid British Standard.

Sources

Approved Document C (2004 edition, incorporating 2010, 2013 and 2016 amendments), “Site preparation and resistance to contaminants and moisture” — confirmed by direct read of the full document to contain no minimum roof-pitch table; its one numeric pitch reference (70°) is an unrelated insulation rule. Read it at gov.uk.
BS 5534, “Slating and tiling for pitched roofs and vertical cladding” — the standard that actually sets minimum pitch by material, size, exposure zone and fixing method. Published and sold by BSI; not reproduced here. See bsigroup.com.

Read this first. This page covers England and Wales, where Approved Document C applies. Scotland and Northern Ireland run their own building standards regimes with their own documents, not checked here. BS 5534 is a paid, private publication — always confirm the current edition directly with BSI, and check the specific product’s own data sheet, before you rely on any pitch figure for a real roof. (Verified against Approved Document C as at 2026-07-31.)

Frequently asked questions

What is the minimum roof pitch in the UK, under Approved Document C?

There is no number. Approved Document C, the guide to Part C of the Building Regulations 2010, has no minimum-pitch table. It gives one pitch figure only: roofs at 70 degrees or steeper count as walls, under an unrelated insulation rule. The real minimum pitch is set elsewhere.

Does Approved Document C set any roof-pitch figure at all?

No. A full search of the current document finds no minimum-pitch clause or table for any roofing material. Not for tile, slate, or sheet. Its scope is ground moisture, wall moisture, and roof weathertightness as a general outcome. It never gives a pitch number to design to.

What actually sets minimum roof pitch in the UK?

BS 5534, 'Slating and tiling for pitched roofs and vertical cladding', plus your maker's own declared minimum pitch for the exact tile, slate or sheet. BSI publishes BS 5534 as a paid British Standard. Approved Document C accepts these as a way to meet the Building Regulations, but states no number itself.

Does this apply across the whole UK?

This page covers England and Wales, where Approved Document C (via the Welsh equivalent) applies. Scotland runs the Building Standards Technical Handbooks. Northern Ireland runs its own Technical Booklets. Those are separate documents, not checked for this page. Confirm which nation's rules cover your job before you rely on anything here.

What should I check before I lay a roof, if the code gives me no number?

Get the current BS 5534 if you design or specify the roof. Then check the data sheet and fixing spec for the exact tile, slate or sheet you lay. A building control surveyor checks your roof against that declared minimum pitch and its exposure zone adjustment, not a code clause.