MODERN CONCRETE ROOFING
Whilst illustrations depict the Coverland Taunus tile, the practices apply to all Coverland & Kulu profiles. Any exceptions will be indicated in bold typeface.
Roof structure terminology
1. Wall plate
2. Truss
3. Valley rafter
4. Hip rafter
5. Batten
6. Eaves
7. Tilting batten
8. Fascia board
9. Verge counter batten 10. Tie Beams
11. Sprocket end
12. Bracing
13. Apex
14. Junction
15. Rafter
16. Hip counter batten
17. Valley counter batten
Rafters/trusses
As per structural requirements. To comply with SABS 563 Softwood structural timber and engineer's specifications.
MONIER Roofing Undertile Membrane
MONIER Roofing undertile membrane agre'ment approved certificate 2004/304.
Battens
To comply with SABS 653 Softwood battens and brandering.
Batten nails
Non-corrodible nails 3,35mm Ø - long enough to penetrate the rafter to a depth of 55mm.
Tiles
To comply with SABS 542 for concrete roof tiles.
Fittings
To suit design criteria.
Tile nails
Non-corrodible clout nails, as supplied by MONIER Roofing - long enough to penetrate the batten to 2/3 of its depth.
Tile clips
Non-corrodible "Storm clip".
Flashings
Non-corrodible flashing materials should be used. To avoid the possibility of electrolytic corrosion, always ensure that flashings, which come into contact with one another, are compatible.
General
Accessories such as roof windows, clear tiles, adhesives and pigments, are as supplied by MONIER Roofing.
Inspecting the Roof Structure
Before battening commences, the main contractor should make sure that the rafter/truss centres do not exceed those recommended for the batten size. The roof structure should also present no abnormality, thereby offering an even plane for battening and tiling.
It is strongly recommended not to proceed until the structure is approved.
Re-roofing
It is unlikely that a roof previously covered with other materials will have the correct structure to carry concrete tiles. A comprehensive assessment is therefore essential and proper adjustment and reinforcement of the structure must be done before laying concrete roof tiles. It is always advisable to contact your nearest MONIER Roofing outlet for expert advice when considering a re-roofing job.
Fixing the Undertile Membrane and Battens
(Work normally carried out by a qualified carpenter.)
The undertile membrane should in all cases be fixed between rafters and battens (except at the lower edge of a bottom course of tiles where it overlaps the tilting batten and/or fascia board into the gutter), and must overlap horizontally and vertically by at least 150mm at all joints.
Eaves overhang
Determine the specified eaves overhang and cut the rafters/trusses accordingly.
Tilting batten
A tilting batten (or fascia board) must be used at the bottom end of the rafters, rising
above the batten line to ensure that the first course of tiles will be on the same plane as the following courses. The average tilting dimension is plus-minus 14mm higher than the battening being used.
Valley undertile membrane
If the roof has valleys, start by fixing a strip of undertile membrane at least 600mm wide, centered on the valley's full length, overlapping the ridge on the top and carrying it well into the gutter at the bottom. Secure the undertile membrane on the edges with clout nails.
Eaves undertile membrane
Lay the first horizontal strip over the rafters starting from the eaves, ensuring that it will carry over the fascia board. Secure this first strip to the rafters with clout nails in the upper half only, leaving the lower half free for draping over the tilting batten and well into the gutter. Care should be taken to ensure that the undertile membrane does not form any troughs where water may be trapped. To achieve this the undertile membrane must be taut or supported, if necessary, behind the fascia board/tilting batten.
If the roof is to have open soffits, it is good practice to install a thin covering (fibre-reinforced cement or other weather-resistant sheet) on top of the rafters for the extent of the eaves or verges overhang before proceeding.
Positioning the bottom and top battens
Fix the batten, which is to carry the first course of tiles on top of the undertile membrane.
The distance of this batten from the fascia board should allow sufficient overhang of the tiles over the fascia board/tilting batten enabling rainwater to discharge efficiently into the gutter (normally 350mm from the outside of the fascia board to the top of the first batten.)
Fix the apex batten temporarily, but accurately, at a distance of 25mm from the apex of the rafters, which is adequate for most pitches.
Calculating the batten gauge
Determine the pitch of the roof and the appropriate batten gauge. Measure the full rafter length and read off the spacings on the table on the following page. Set the tilting batten and first batten, then proceed to batten at the centres shown in the table. Make sure that the battens run parallel to each other at all times.
Split apex
A split apex is a design feature. When calculating the batten gauge, the higher apex should always be used. A short course can occur at the lower level apex.
Roof undertile membrane and battening
Proceed with fixing undertile membrane horizontally with clout nails, observing the recommended overlaps. Batten up simultaneously to the apex ensuring that the batten joints are always located on a rafter. It is bad practice to join all the battens on the same rafter.
Valleys
At valleys, the horizontal strips of undertile membrane shall overlap undertile membrane previously fitted. Determine the width of the valley flashing to be used. Secure the valley counter battens along both sides of the valley to the rafters securing the undertile membrane. Horizontal battens are now mitred and secured to the valley counter battens.
Hips
At hips, the undertile membrane may be cut close to the hip rafter, or may overlap one another on both sides of the hip rafter. A strip of 600mm wide undertile membrane is then placed over the full hip length, overlapping the ridge at the apex and carrying down into the gutter at the bottom. The hip counter battens are secured to the rafters as close to one another as possible along the length of the hip, securing the undertile membrane. Horizontal battens are now mitred and secured to the hip battens.