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IS 5119:2000 (Part 1) is the Indian Standard (BIS) for laying and fixing of sloped roof covering, part i: slating. This standard provides guidelines for the laying and fixing of natural slates on sloped roofs. It covers materials, roof pitch, lap requirements, fixing methods using nails, and detailing for eaves, ridges, and valleys to ensure a weather-tight finish.
Code of Practice for Laying and Fixing of Sloped Roof Covering, Part I: Slating
Overview
Status
Current
Usage level
Specialized
Domain
Architectural — Building Construction Practices incl. Painting, Varnishing
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! Ensuring correct head lap and side lap is critical for weather-tightness, especially in areas with high rainfall or wind.
! Use of non-corroding nails (copper or aluminium) is essential for the longevity of the roof, as steel nails will rust and fail long before the slate.
! Proper selection and spacing of battens are crucial to support the weight of the slates and prevent sagging.
BS 5534:2014+A2:2018BSI (British Standards Institution), United Kingdom
HighCurrent
Code of practice for slating and tiling for pitched roofs and vertical cladding
Directly equivalent, covering the design, materials, and fixing methods for natural slate roofing.
Slate Roofs: Design and Installation Manual, 2010 EditionNSA (National Slate Association), USA
MediumCurrent
Slate Roofs: Design and Installation Manual
Authoritative industry guide covering installation, though methods and terminology differ from IS/BS codes.
DTU 40.11AFNOR (Association Française de Normalisation), France
HighCurrent
Couvertures en ardoises (Slate roofing)
French national standard for slate roof installation, sharing many core principles with IS 5119.
EN 12326-2:2011CEN (European Committee for Standardization), Europe
LowCurrent
Slate and stone for discontinuous roofing and cladding - Part 2: Methods of test for slate and carbonate slate
Specifies test methods for the slate material itself, not the installation code of practice.
Key Differences
≠IS 5119 provides prescriptive fixing guides (e.g., two nails per slate), whereas BS 5534 mandates detailed wind uplift calculations for the specific site location, requiring stronger fixings like clips in high-exposure areas.
≠Modern standards like BS 5534 strongly advocate for dry-fix mechanical systems for ridges, hips, and verges. IS 5119 still details traditional mortar bedding techniques for these areas, which are now often considered less durable.
≠BS 5534 places significant emphasis on the role of the roofing underlay (breather membrane) as an engineered, wind-resistant component of the system. IS 5119 treats under-felting as a more traditional secondary water barrier without the same structural considerations.
≠The use of counter-battens to create a ventilation channel is a standard recommendation in BS 5534 for certain roof constructions ('cold roofs'), whereas it is not a primary focus or requirement in IS 5119.
Key Similarities
≈Both standards are founded on the fundamental principle of double-lap slating, where headlap and side lap create a weatherproof covering.
≈The inverse relationship between roof pitch and required headlap is a core concept in both IS 5119 and its international counterparts; steeper roofs require less headlap.
≈Both codes specify using two non-corroding nails (e.g., copper, aluminium alloy) as the standard method for securing each slate to the battens.
≈The practice of sorting slates into three or more thickness grades before laying to ensure an even and well-presented roof surface is recommended in both IS 5119 and international best practice guides.
Parameter Comparison
Parameter
IS Value
International
Source
Minimum Recommended Pitch
22.5° (1 in 2.4)
Varies by slate size and exposure, can be as low as 20° for large slates in sheltered areas.
BS 5534:2014+A2:2018
Minimum Headlap (at min. pitch)
115 mm (for 22.5° pitch)
100-110 mm (for 20-22.5° pitch, depends on exposure zone and slate size)
BS 5534:2014+A2:2018
Nail Material
Copper or Aluminium Alloy.
Copper, Aluminium Alloy, or Stainless Steel (Grade 304 or 316).
BS 5534:2014+A2:2018
Nail Penetration into Batten
Minimum 15 mm.
Minimum 15 mm into the batten.
BS 5534:2014+A2:2018
Batten Size (Rafters at 600mm)
50 x 30 mm.
25 x 50 mm (but must be factory graded to BS 5534).
BS 5534:2014+A2:2018
Verge Treatment
Undercloak with mortar bedding or slate-and-a-half with mortar pointing.
Dry verge systems are preferred; mortar bedding is discouraged.
BS 5534:2014+A2:2018
Holing of Slates
Holes to be punched from the back (bed) of the slate.
Holes to be drilled or punched from the back to form a countersink on the face.
NSA Manual / BS 5534
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
Minimum roof pitch (moderate exposure)25 degrees
Minimum head lap for 25° pitch roof80 mm
Minimum side lap50 mm
Recommended nail materialCopper or Aluminium
Typical batten size for 400mm rafter spacing38 mm x 25 mm
Key Formulas
Batten Gauge = (Length of Slate - Head Lap) / 2
Tables & Referenced Sections
Key Tables
Table 1 - Minimum Roof Pitches and Head Laps for Slates
Table 2 - Sizes of Battens for Tiled and Slated Roofs
Key Clauses
Clause 4 - Materials
Clause 5.3 - Lap
Clause 5.4 - Gauge
Clause 6 - Fixing of Slates
Clause 7 - Treatment at Eaves, Ridges, Hips, Valleys and Abutments