Installation of roof gutters and rainwater downpipes made of NedZink NTZ®
A distinction is made in the installation of roof gutters supported by brackets and roof gutters in a wooden box. These different ways of installation will be discussed separately.
Roof gutters supported by brackets
The hot dip galvanized gutter brackets to be used must meet EN 1462 and must, according to the specifications of the manufacturer, be suitable for the gutter type to be installed. The form of the gutter brackets is determined by the roof gutter, just as the manner of attachment.
The form of standard and non-standard gutter brackets must be adjusted to the form of the wall plate, the required slope, the pitch of the roof and the position of the gutter to be installed (back height higher than front height).
Slope of the gutter
The slope in the direction of the outlet piece must amount to at least 2 mm per metre gutter length.
A gutter bracket must be attached to the wall plate with at least 2 galvanized or stainless steel screws.
The distance between the gutter brackets amounts to max. 660 mm centre to centre. (bead 20 mm and zinc thickness in accordance with EN 612). The brackets are placed under the thread to secure the slope in the direction of the outlet piece. The bracket has been provided with a lip for the attachment of the bead, fig. 1, that fits in the bead or a bracket without lip but with a hot dip galvanized steel angle profile, fig. 2, that fits in the bead. Several other attachment techniques are to be found in Europe. The back height is attached with a clip of hot dip galvanized steel or stainless steel.
The galvanized steel angle profile must meet the same standards as the gutter brackets.
Roof gutters and accessories
Roof gutters made of NedZink NTZ® must meet EN 612.
The minimum material thickness is 0.65 mm, 0.70 mm or 0.80 mm depending on the type of gutter and developed width of the gutter. The standard length varies from 2, 3, 4 to 6 metres depending on the type of gutter and customs per country.
Two important types of gutter can be distinguished, namely: the suspended gutters, fig. 4, and the box gutter, fig. 3. Non-standard prefab gutters can be ordered according to a drawing or made by the metal worker from NedZink NTZ® sheet material. Non-standard prefab gutters must also meet EN 612.
The accessories, namely: end pieces left and right, expansion sleeves left and right, separation slides and outlet pieces can be supplied by the wholesale trade or be made by the metal worker from NedZink NTZ®.
Pre-treatment of roof gutters
The gutter parts are preferably pre-treated in the workshop,
- Making gutter parts to length.
- Making (and if possible soldering) mitres.
- Soldering end pieces, expansion sleeves and outlet pieces.
See for example figs. 6, 7 and 8.
Installation of roof gutters supported by brackets
The gutter parts must be preferably installed from left to right and against the slope (from low to high). The structural conditions do not always allow this. When choosing another installation direction the installation from low to high is more important than from left to right (drainage overlap!).
At one side of the bead a locating edge or fitted edge may have been left open to facilitate the joining together of the gutters. The gutter parts, starting at the bead, are joined together with a minimum overlap of 10 mm. With the same rotating movement the gutter parts with the bead are placed in the correct position over the lip or steel angle profile of the brackets.
The clip at the back height of the bracket is now bent downwards over the water check of the back height, in such a way that the gutter can continue to move in the circumstances of contraction and expansion (The use of nails for the same purpose is not permitted as this is disastrous for the service life of the gutter!).
The overlap of the gutter can now be soldered. Note the minimum overlap of 10 mm and a flow through of the soldering of a least 10mm. See for soldering NedZink Advice TZ2: “Soldering of NedZink NTZ®”.
The distance between the side of an outlet piece and a bracket must be at least 60 mm, see fig. 5. An expansion device must always be supported by a bracket,
see figs. 7, 8 and 9.
Expansion devices are necessary in order to absorb the expansion and contraction of the roof gutter. Where and when an expansion device must be used is shown in table 1.
Table 1 Expansion device in roof gutter*
Gutters provided with bead 20 mm and material thickness 0.80 mm
(Girth 300 mm in 0.70 mm)
Max. gutterlength in metres without expansion-sleeve
Max. distance in metres between 2 expansions devices
Developed width of the
gutter ≤ 550 mm
Developed width of the
gutter > 550 mm
Gutter in the box
2 free ends ****
1 free end ****
Gutter in the bracket
2 free ends ***
1 free end ***
* see figures 7 + 8 *** The free expansion space must be at least 10 – 15 mm
** see figure 9 **** The free expansion space must be at least 20 mm
Roof gutters in a wooden box
The support forms part of the structural construction and is usually made of wood. NedZink NTZ® can be excellently applied directly to unplaned wood. It is advisable not to use water-resistant wood glued together. It is undesirable for water to remain in the enclosing box in the event of a calamity. The fitting first of rough unplaned wooden parts in the bottom is recommended for a concrete substructure.
If this is impossible then a layer of natural glass fibre 3 – 5 mm can be fitted under the zinc bottom.
This prevents corrosion due to water on the underside of the zinc.
Before applying the zinc check whether the supportive wooden box is clean and does not contain projecting nail heads or screws. Then the box is measured at various places and the 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 that the outlet piece with the rain pipe slipped around it must have an oval cavity with at least 20 mm space to the left and to the right and in the two other directions minimum 5 mm. See figs. 10a and 10b.
Construction of the roof gutter
Make a drawing of the measured supportive box and draw in the zinc-titanium gutter, see fig. 10. The following basic rules should be observed:
- The upper opening width of the gutter must be at least 4 mm smaller than that of the box.
- The botttom 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 falls before the edge of the box and not on it.
- The back height min. 10 mm higher than the front height, in the case of gutter with water check.
- The slope of the gutter equal to that of the box including any bent forms.
- The further dimensional proportions in accordance with EN 612.
- The ends of the gutter must have at least 10 mm space in relation to the ends of the supportive box
(see also: “Expansion”).
The roof gutters, made of NedZink NTZ®, must meet EN 612.
If the dimensions of the box permit, use Standard Prefab gutters or otherwise non-standard gutters (tailor-made) of NedZink NTZ®.
Pre-treatment of roof gutters
The roof gutters are preferably pre-treated as far as possible
in the workshop i.e.:
- making gutter parts to length.
- making (and if possible soldering) mitres.
- soldering end pieces, expansion sleeves and outlet pieces.
See also figs. 6, 7 and 8.
Installation of roof gutter in a wooden box
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 galvanized or stainless steel flat-headed nails of min. 22 mm in length.
The distance between the clips is max. 660 mm centre to centre. At a developed width of = 600 mm, a max. clip distance of 500 mm is advised. The clip must have such a form and overhang that the clip fits at least up to 3/4 in the bead cavity and fixes the gutter in its correct position (see fig. 10). Clips of min. 30 mm width are further attached to the wooden back height at the same distances, which are
bent over the water check of the gutter, see fig. 10b. For gutters with a large developed width e.g. = 700 mm and a bottom width of = 300 mm the fitting of a sliding clip in the bottom is advised. This bottom clip may in no circumstances be soldered to the gutter.
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!).
The gutter parts with the bead are now hooked up over the fastening clips and tilted in the box with a minimum overlap of 10 mm. The gutter is pressed on the bottom of the box and secured in this position by bending the clips of the back height over the water check in such a way that the gutter can continue to move in the event of contraction and expansion. After fitting any mitres, the overlapping seams can be soldered. Make sure there is an overlap of at least 10 mm and a flow through of the solder of at least 10 mm. See for soldering: NedZink Advice TZ2: “Soldering of NedZink NTZ®”.
Expansion sleeves are necessary to absorb the expansion and contraction of the roof gutter. Where and when an expansion device must be used is shown in table 1.