Thank you for purchasing metal sheets manufactured by Nautracom. What makes our sheets exceptional is our attention to technical, quality and aesthetic details. Follow the basic rules of sheet installation provided in this manual to enjoy the product for years.
Check the roof geometry by measuring the length of diagonals. If they are not identical, it means that the roof is deformed. In such case, minor differences (20mm ~ 30mm) can be levelled by a barge board and barge flashings. Major differences need to be corrected before battening. It is also important to check the roof pitch angle. The roof pitch should be at least 8°; if less than 12°, install a special seal on the transverse joints of the panel.
Before starting any roof work, prepare suitable tools: a measure, a saw (only a hand saw), snips, a nibbler, a screwdriver with stepless speed regulation, a rubber mallet, a chalk cord, roofing pincers, a life safety rope with a harness, suitable boots with a rubber sole.
Use the high-quality breathing roofing sheet (membrane) available from Nautracom over adapted (habitable) attics. Breathable sarking membrane allows for proper air circulation and drains away the condensed vapour into the gutter. Properly installed breathable sarking membranes are a guarantee for a moisture free attic rooms. When installing a low water vapour permeability membrane, remember to leave a gap between the membrane and the thermal insulation of the attic (at least 20mm).
The air gap reduces the condensation of water vapour in the attic in the case of sudden temperature jumps and prevents the roof heating up resulting from hot sheets during the summer. Remember to keep the foil sheet a little slack between the rafters to enable proper drainage of condensed steam. Do not, however, allow the sheet to touch the insulation, this will transpire the water back from the foil surface to the thermal insulation. It is recommended to use high water vapour permeability membranes (area 1000g/m2/24h). They are more expensive, but there’s no need to leave the ventilation gap. Breathable sarking membrane is not resistant to UV radiation and chemicals such as oil from a chain saw. They can usually lie on a roof without covering for a few months. Depending on the manufacturer and the type of membrane, the roofing sheet should be laid within up to 4 months.
The membrane is laid in horizontal stripes providing about a 100mm lap or according to the manufacturer’s marking on the membrane. Start from the bottom of the roof slope.
Full roof boarding is recommended for the roofing panels with vertical snap-on seams. Once the structure has been finished, install the foil sheet directly over the boards. It is possible to install the panels on a structure made of battens and counterbattens. First install the roofing membrane sheet by attaching it to the rafters with counterbattens. Then attach the battens to the counterbattens at a spacing of 250mm. 32mm x 70mm battens are usually used. Do not leave the foil sheet on the first batten when installing the roofing panels with seams.
Do not use grinding machines to cut the metal sheets (e.g. angle grinders) rapid temperature increase will damage the organic and galvanic coats at the cuts. Moreover, the hot swarf damages the paint over a large surface area of the metal sheet.
Verify the geometry of the roof before attempting to install. First install the gutters and the eaves flashing. Attach the gutter skirt to the board or the first batten with flat-head sheetmetal screws. Then lay out the sheets across the roof slope to keep the same width of the end metal sheets after the installation.
Installing the first metal sheet
Start the installation of the metal sheets from either end of the roof (left or right). It is very important to lay the first sheet at the proper angle to the eaves. It is difficult to correct any twisting. Fasten the first metal sheet by bolting it to the substructure with the screw placed in the first bottom hole of the fastener. Then align the sheet precisely against the eaves and install the remaining screws.
Installing the next metal sheets
The next sheets are fastened to the previous ones with the snap-on lock. Overlap the next sheet on the previous one and firmly press down. The snap-on is locked at the entire length from top or down. Once the sheet is in position, bolt it down at the integrated fastener. By principle, install the successive sheets in perpendicular to the eaves line.
Long roof slopes require cross joining of metal sheets. Remember that the joining must not be in a single line, but alternate. Use metal sheets of two lengths alternately in each Install the sheets so that the upper sheet overlaps the lower one by 200 to 400mm, depending on the roof gradient. Do the cross joint by cutting out the snap-on lock on both sides of the lower metal sheet at the height of the welt.
Drive the screws always in the centre of the fastener holes. Remember to leave some play to allow the sheets to move against the screw. It is critical, since metal roofing expand thermally, i.e. from heat. Too tight screws may unseal the roofing. Proper fastening is achieved by unscrewing the fully tightened screw by one half of turn. Bolt the end metal sheets to the substructure with screws spaced every 250mm or to each batten. The centre metal sheets are fastened every 500mm or by bolting to every other batten. Also bolt all sheets to the first three battens from the bottom and to the last batten at the top. If full boarding is used, fasten at the bottom and at the top with the spacing of the battens.
Before installing the ridge tile, first install the ridge slat on the banels between the seams. The ridge slat ensures proper ventilation of the roof and enables installation of the ridge tile. Bolt down the ridge tiles to the slat with 4.8mm x 20mm farmer screws and EPDM washers.
Eaves and other roofing work
Install the eaves and complete all other roofing work following the method for a traditional vertical seam. The method is shown in our installation instructions for panel metal sheets with vertical seams.
Once the roof works are finished, clean the roof of any filings and metal debris. Any metal elements that are left on the roof may create corrosion centres. Preferably use a soft brush that does not cause any scratches. When walking on the roof, wear soft sole boots and step on the valleys. Preserve the cuts and scratches by degreasing and coating with a primer paint. Do not use spray paints. When selecting a roofing with vertical seams remember that the bulging of the installed panel is normal and may occur under specific weather conditions (e.g. during strong wind) with audible rippling of the sheets. This does not affect the value of the product adversely, since it results from the properties of the section and from the vertical seaming method.
Under normal conditions, inspect the roof covering at least once a year. Remove any contaminations which bind moisture, such as dirt, leaves, etc. Protect any damages with a touch-up paint.