System Description
- Roof drainage system to provide protection against the penetration of moisture from exterior or basement walls.
- Roof drainage system consisting of rain gutter, accessories and connecting rainwater downpipe
To prevent water from leaking into exterior walls or cellar walls, the rainwater running off from the roof should be drained via a roof drainage system. As a rule, this roof drainage system consists of eavestroughs and rainwater downspouts connected thereto, which, in turn, lead the rainwater into the municipal drainage system, a rainwater utilization system or seepage through trenches or troughs.
As a rule, the drainage system should be taken into account in the overall design - from the rainwater intake area to gutters and run-offs, the interior drainage system and the main piping system, right to the conduit connection.
Dimensioning
- Roof drainage systems must be calculated hydraulically for sufficient dimension
- Applicable DIN standards and regulations must be adhered to at all times:
DIN EN 12 056-3
Gravity drainage systems inside buildings, Part 3 - roof drainage, design and measurement
DIN 1986-100
Drainage systems for buildings and properties, Part 100 - Additional requirements for DIN EN 752 and DIN EN 12 056
Technical information from the ZVSHK (sheet metal standards).
Dimensioning bracketed and interior gutters
As of July 2001, bracket-mounted and interior roof drainage systems must be dimensioned for sufficient sizing by means of an hydraulic calculation, contrary to the all-inclusive gutter calculations, which were valid up until now.
For economic reasons and to secure the self-cleaning ability, bracket-mounted roof drainage systems are calculated based on an average amount of rainfall. In accordance with DIN 1986-100, this amounts to the local five-minute rainfall intensity, which must be expected once every 2 years. The rainfall intensity to be calculated must be obtained from the local authorities or from the German Weather Service.
The precipitation area and the run-off coefficient of the roof surfaces projected in the layout of the building, which takes into consideration the time delay between the rainfall measured by the rainfall intensity and the actual run-off (DIN 1986 - 100), are factored into the hydraulic calculation. Influencing factors such as gutter length, gutter angle, leaf collection boxes and downpipe distrotion, which can reduce run-off capacity, are also specified in the standards and regulations and must be considered in the calculation.
RHEINZINK offers an online dimensioning program to measure bracket-mounted roof drainage systems. This program was developed specifically for RHEINZINK-products. It is based on DIN standards and includes all RHEINZINK-products. The bill of materials generated can be forwarded directly to Purchasing.
Fastening
- Fastening the gutters with specially prepared brackets
- Alternative: RHEINZINK-snap-lock bracket system
- Connecting the individual gutter lengths by soft welding or glueing
- Fastening the rainwater downpipe with pipe straps
- Alternatives: RHEINZINK-Universal
Gutters are fastened by brackets which have been specifically created for this purpose (according to DIN EN 1462). These are fixed either to the fascia board, the rafters (sidways, if necessary) or the wall.
The gutter brackets must have large enough dimenstions to meet local demands. DIN EN 1462 / DIN 612 divides gutter brackets into 4 load categories.
The RHEINZINK-snap-lock bracket system (load factor 4 in accordance with DIN 1462) is an innovation for a traditional fastening technique. The system is characterized by quick installation, which can be done without cutting off the gutter bracket.
Distance
± 40 mm |
load |
| normal/category |
high/category |
| 700 mm |
1 |
3 |
| 800 mm |
2 |
4 |
| 900 mm |
3 |
snap-lock bracket |
Table: allocation of load category of gutter brackets to the maximum fastening distance
As a rule, rainwater downpipes are attached to the façade with traditional pipe straps, without impeding thermal expansion of the downpipe due to changes in temperature. Thus, the distance of the pipe straps, in accordance with DIN for pipes of nominal size = 100 mm, can be up to 3.0 m.
Compared to conventional pipe straps, the RHEINZINK-universal downpipe bracket is almost invisible.
Expansion elements
- Expansion spacings should be installed according to nominal size.
In order to ensure the thermal expansion of RHEINZINK-gutters due to changes in temperature, the following maximum dilatation-free lengths apply:
| Type of gutter |
Nominal size of expansion elements |
max. distance (m) |
| Half-round and box-type in accordance with DIN EN 612 Roof gutter |
≤ 500 |
15,0 |
| Half-round and box-type in accordance with DIN EN 612 Seam gutter |
≥ 400 |
9,0 |
| Custom-made shapes |
> 500 |
6,0 |
Table: Expansion spacings for exterior eavestroughs
Half of the expansion-free value must be kept for corners and ends, i.e. of fixed points in the gutter.
RHEINZINK-eavestrough expansion elements are specifically suited to accommodate expansion. These can be installed in the water level as prefabricated components.
Lengthwise inclines
- Horizontal gutter installation is possible.
RHEINZINK- Factory Recommendations recommend horizontal installation for aesthetic reasons. The "Guidelines for Metal Roofing Systems" (ZVSHK/ZVDH/FVHF) recommend that installation be done on a lengthwise incline of at least 1 mm - 3 mm/m. However, a self-cleaning effect only occurs at an incline of 5 mm/m. Stagnant water in the gutters does not lead to any recognizable disadvantage and represents no defect.
Crosswise incline
- An incline across the eavestrough is not required.
- The rise of the rear edge of the gutter should be between 8 mm - 20 mm.
An incline across the eavestrough is not required. However, DIN EN 612 specifies exactly how much higher the rear wall should be, to ensure that water will not penetrate the roof structure, in the event of a water back-up.
#Roof gutter
- Lengthwise incline ≥ 5 mm/m
- Roof pitch ≥ 15°
Since it drains to the outside, the roof gutter is considered part of the exterior drainage system. It is installed on the roof membrane with a recommended minimum slope of 5 mm/m. The banking to the roof side of the roof gutter over the front gutter beading must be guaranteed to be at least 10 mm. Therefore, pitch should not fall below 15° in order to avoid cutting the gutter more than 1000 mm.
| Standard size |
Minimum roof pitch |
| 400 |
≥ 55° |
| 500 |
≥ 45° |
| 650 |
≥ 25° |
| 800 |
≥ 20° |
| 1000* |
≥ 15° |
Table: Standard sizes of roof gutters/edge gutters (* special case)
The necessary seam covering can be done in various types of roofing. The most common one is the double lock standing seam cover. Seam covers in angled standing seam, Click roll, tiles and in a smooth finish, are possible without restriction. RHEINZINK factory recommendations and "Guidelines for Metal Roofing Systems" (ZVSHK/ZVDH/FVHF) should always be considered when working on a roof gutter.
Gutter on top of the cornice
- Technical requirements for exterior drainage must be followed
The only difference between the gutter on top of the cornice and the bracket-mounted gutter is the additional installation of a cornice coping. However, from a technical point of view, it should be regarded as completely separate from the gutter. If RHEINZINK-roof drainage accessories cannot be installed, these must be made by hand.
The cornice coping can be positioned with continuous cleats or glued onto a full-surface substructure. The minimum lateral slope of the coping should not fall below 3° in order to avoid standing water. Heights, spacing between drip edges, overlap height can be found in "Guidelines for Metal Roofing Systems" (ZVSHK/ZVDH/FVHF).
Gutter behind the cornice
- Exterior and interior construction possible
The moment the gutter behind the cornice cannot drain towards the outside, it is considered to be an interior eavestrough. Technical advice as well as dimensioning for interior drainage, in accordance with DIN EN 12056, must be followed in this case.
If the width of the cornice is under 50 mm, the gutter which lies behind the cornice, can be made in one piece, therefore as an exterior eavestrough. The crafted box gutter can either be inserted into gutter brackets fabricated specifically for this purpose or else into a full-surface wooden construction.
If the width of the cornice is greater than 50 mm, the gutter must be made in two parts.
Requirements for thermal linear expansion must also be considered here. As a rule, the RHEINZINK-roof drainage program has the appropriate products available.
