LAYING AND FIXING SPECS
Recommended laying and fixing specifications for Coverland & KULU concrete roof tiles
The following laying and fixing specifications for Coverland & Kulu concrete roof tiles have been established in accordance with SABS 062/1956 (Code of Practice for fixing concrete roof tiles), SABS 0160/1980 (Code of Practice for the general procedures and loadings to be adopted for the design of buildings), BS 5534 - Part 1/1978 (Code of Practice for slating and tiling and design), MONIER Roofing technology data, and extensive experience gained by MONIER Roofing.
Roofs in exposed and coastal areas can experience severe wind lifting forces. In these situations special recommendations for additional mechanical fixings apply. The principal factors to be considered in deciding on the necessity for additional fixing are:
1. The exposure of the site.
2. The height above ground of the roof.
3. The pitch of the roof.
4. The higher wind loadings encountered at eaves and verges.
5. Environmental influences.
Specific laying and fixing specifications for these locations must be considered for each situation.
Definitions
Rafter pitch
The angle of elevation between the horizontal plane and the angle of the rafter. Roof pitch = rafter pitch
Tile pitch
The angle of elevation between horizontal and the tile when laid. Note: The tile pitch has a lower angle of elevation than the rafter pitch.
Low roof pitch 17° to 25°
Normal roof pitch 26° to 35°
High roof pitch 36° and above
Laying specifications
Headlaps
The minimum headlap for Coverland & Kulu concrete roof tiles is 100mm on 17°-25° and 75mm on pitches of 26° and above. All Coverland & Kulu concrete roof tiles, with the exception of the Elite, should be laid “straight-bond".
Mechanical fixing
Coastal regions (up to 30km inland): Aluminium alloy serrated clouthead nails of the correct length to suit the profile.
Inland regions: Electroplated serrated clouthead nails of the correct length to suit the profile.
Non-corrodible "stormclips" should always be used where specified, ensure correct stormclip is used for specific profiles.
Fixing specifications
The following fixing guide should provide a sound functional roof in each of the defined exposure categories. However, it cannot encompass all possible circumstances, or the freak occurrence worse than the "once in 50 years" prediction. Special laying and fixing specifications must be considered for each situation where the roof pitch, height of the roof, exposure of the site and/or environmental influence are unknown, in doubt, or felt to be critical. Please refer to MONIER Roofing for advice in these circumstances.
Category A - Unexposed areas
All inland regions other than certain specified areas.
Category B - Semi-exposed areas
Coastal regions and certain inland areas.
Generally the area within 30km from the coastline, the top of the escarpment or the watershed of the first mountain inland. Whilst cognizance should be taken of local practices, the application of good roofing practice should not be compromised for expediency.
Category C - Exposed areas
Critical coastal areas, and certain inland areas.
The classification of exposure categories assumes the use of a suitable underlay, properly fixed over the total area of the roof including the gable end and eave overhangs.
When possible, local knowledge and local wind speed data should be used in the assessment of the exposure category. (Refer to CABS 0160/1980 for Regional Basic Design Wind Speed determination.)
The exposure category of the required roof may be assessed using the following table:
Fixing guide
Category A - Unexposed areas
All inland regions other than certain specified areas.
Mechanically fix two courses of tiles at the eaves, ridges and verges for the full overhang, whichever is greater. Cut tiles at hips, valleys and abutments to be secured by nailing, wiring, or multipurpose adhesive e.g. Coverfill. It is recommended that closed soffits be fitted on all verge and eave overhangs.
Roof pitches
17° to < 26° - undertile membrane mandatory
26° to < 45° - undertile membrane recommended
45° to < 55° - undertile membrane recommended, each tile to be nailed
55° to vertical - undertile membrane mandatory, each tile to be nailed and clipped
Category B - Semi-exposed areas
Coastal regions and certain inland areas.
Mechanically fix a band of tiles (x) equal to a fifth of the number of courses on the rafter lengths at the eaves and ridges, and also at chimneys and abutments.
Mechanically fix a band of tiles equal to (x) along (y), as calculated above, at each verge (or the full overhang, whichever is the greater.) Tiles at hips, valleys and abutments to be secured by nailing and wiring every third tile on the roof.
Closed soffits must be fitted to all verge and eave overhangs.
Roof pitches
17° to < 26° - undertile membrane mandatory
26° to < 45° - undertile membrane recommended (mandatory at the coast)
45° to vertical - undertile membrane mandatory, each tile to be nailed and clipped
Category C - Exposed areas
Critical coastal areas and certain inland areas.
Roof pitches
17° to < 26° - undertile membrane mandatory, each tile to be clipped
26° to < 45° - undertile membrane mandatory, each tile to be nailed or clipped
45° to vertical - undertile membrane mandatory, each tile to be nailed and clipped
Closed soffits to be fitted at all verge and eave overhangs.