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Installing slates and tiles in accordance with BS5534

by NFRC | Jan 09, 2019

In the third of a series of articles that examine how to comply with the revised BS5534 code of practice, we focus on the third task – installing slates and tiles.

BS5534 is the code of practice for installing slates and tiles to new-build pitched roofs and vertical cladding. Although it’s not a legal requirement, a roof specified to the code of practice can be upheld by law, so you should refer to the complete BS 5534 document or seek advice from the manufacturer.

Single lap tiles

Single-lap tiles should have at least the following fixings.

  • For all roof areas and rafter pitches, every tile should be mechanically fixed (such as such as hook, nail or clip)
  • For rafter pitches of 45° and over, each tile should be nailed with at least one nail
  • For rafter pitches of 55° and over, including vertical, the tail of each tile should be mechanically fixed
  • At verges and abutments, and at each side of valleys and hips, the end tile in every course should be mechanically fixed
  • At eaves and top edges, one course of tiles should be mechanically fixed

Nails

Nails for fixing single lap tiles should be able to penetrate the batten 15mm and the diameter should be as per the manufacturer’s recommendations so that they have enough resistance to wind uplift.

Double lap tiles

Always refer to the manufacturer’s guidelines, however, in general:

For nibless tiles

Use two nails to fix each tile.

For nibbed tiles

For rafter pitches below 60° use two nails in at least every fifth course; for rafter pitches of 60° and above, use two nails on every tile, including vertical tiles (depending on the manufacturer's recommendations).

Verges and abutments, and at each side of valleys and hips

Twice nail or mechanically fix the end tile in every course.

Eaves and top edges

For eave tiles, the first course, the last full top course and ‘toppers’ should be nailed or mechanically fixed.

Nails

Nails for plain tiles should be at least 2.65 mm in diameter and long enough to provide at least 15 mm penetration into the battens.

Slates

Slates and driving rain

The UK has four categories of exposure to driving rain from sheltered through to very severe, the most severe areas of Great Britain, being Cornwall and the western parts of Wales and Scotland (see map). Driving rain in relation to the location and pitch of the roof will determine the side and head-lap.

Minimum pitch

The roof pitch should be at least 20, which is influenced by the length, head-lap and thickness of the slate. Where the thickness of natural slates reduces their pitch by 3°or more, select the next lower rafter pitch to determine the recommended head-lap and slate width.

Minimum fixing on double-lap slates

Double-lap slates should be fixed with at least two nails to every slate when centre-nailed.

Length of slate nails

The length and diameter of nails should be appropriate to the thickness of the slates and their position on the roof and should provide a minimum of 15mm penetration into the batten.

Minimum pitch

The roof pitch should be at least 20, which is influenced by the length, head-lap and thickness of the slate. Where the thickness of natural slates reduces their pitch by 3°or more, select the next lower rafter pitch to determine the recommended head-lap and slate width.

Minimum fixing on double-lap slates

Double-lap slates should be fixed with at least two nails to every slate when centre-nailed.

Length of slate nails

The length and diameter of nails should be appropriate to the thickness of the slates and their position on the roof and should provide a minimum of 15mm penetration into the batten.

BS5534-driving-rain

Minimum pitch

The roof pitch should be at least 20, which is influenced by the length, head-lap and thickness of the slate. Where the thickness of natural slates reduces their pitch by 3°or more, select the next lower rafter pitch to determine the recommended head-lap and slate width.

Minimum fixing on double-lap slates

Double-lap slates should be fixed with at least two nails to every slate when centre-nailed.

Length of slate nails

The length and diameter of nails should be appropriate to the thickness of the slates and their position on the roof and should provide a minimum of 15mm penetration into the batten.

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