Roof gutters in a wooden box
This type is fully supported by a structural construction. In most cases it consists of a wooden box structure.
• The bottom width of the gutter must be at least 10 mm smaller than that of the box. The back height min. 10 mm higher than the front height.
• The gutter parts must be preferably installed from left to right and against the slope (from low to high). The construction conditions may not always allow for this. When choosing another installation direction the installation from low to high is more important than from left to right (drainage overlap!).
• Clips are attached at the edge of the front height of the box with a minimum width of 70 mm and a thickness of 0.80 mm. Attach the clips with 3 galvanised or stainless-steel flat-headed nails. A clip must pierce approximately ¾ into the bead. Secure the gutter with clips of 30 mm wide at the rear upright. The maximum clearing distance is 660 mm.
• If the bottom width of the gutter is greater than 300 mm, a clip must be applied under the seam on the bottom of the gutter. The overlap of the clip must then be 25 mm and the clip may not be soldered.
• The distance between the clips is max. 660 mm centre-to-centre. Clips of min. 30 mm width are further attached to the wooden back height at the same distances and are bent over the water check of the gutter.
• The outlet piece in the supporting box construction must be spacious enough to allow the gutter to contract and expand. This means that the outlet piece, with the rain pipe slipped around it must have an oval cavity with at least 20 mm of space.
The support is part of the building construction and is usually made of wood. Gutters of NedZink material can be applied directly to unplaned wood. NedZink recommends installing a vapor-permeable layer on newly impregnated and bonded wood at the bottom of the gutter tray in order to prevent attack by condensation on the backside of the zinc. The same advice also applies to supports of concrete or other stony materials, where the separating layer also prevents wear on the zinc. Before applying the zinc, check that the supporting wooden container is clean and does not contain protruding nail heads or screws.
The box is to be measured at various places and following measurements should be taken:
• Upper opening width.
• Bottom width.
• Height and slope of front height and rear height of the wooden box.
• Thickness of the edge of the front height of the wooden box.
• Length of the various gutter surfaces.
Opening of the outlet piece
The outlet piece in the supporting box construction must be spacious enough to allow the gutter to contract and expand. This means the outlet piece, with the rain pipe slipped around it must have an oval cavity with at least 20 mm of space to the left and to the right and in the other two directions, at least 5 mm. See figure 3.1.8.
Design of the gutter
See Figures 3.1.8 & 3.1.9. The following basic rules must be observed:
• The upper opening width of the gutter must be at least 4 mm smaller than that of the box.
• The bottom width of the gutter must be at least 10 mm smaller than that of the box.
• The front height of the gutter must be 1 to 2 mm larger than that of the box.
• The bead protrudes over the edge of the box and does not rest on it.
• The back height min. 10 mm higher than the front height.
• The slope of the gutter is equal to that of the box including any bent forms.
• The further dimensional proportions in accordance with NEN-EN 612.
• The ends of the gutter must have at least 10 mm space in relation to the ends of the supporting box