Layout and Fastening
- The gutter will be delivered to site in custom run lengths up to 6 metres and stored on dunnage clear of the ground.
- Fascia brackets are to have a minimum of 3 nail or screw fixings per bracket per rafter.
- Gutter brackets shall be fixed with a minimum of 2 screws to the outside face of the fascia panel to a line to provide sufficient fall to the outlet position to avoid ponding in the gutter.
- Using a string line between the top and bottom bracket of each run fix brackets to the correct fall at bracket centres less than the maximum recommended spacings.
- To achieve this, a minimum fall of 1:500 is recommended. The levelness of the structure shall not be relied upon to determine fall.
- Gutter bracket fixings can be screws or nails depending on the substrate and gutter size, and shall have a durability equal to or better than the anticipated durability of the bracket or gutter. Large gutter sizes above Box 125 will require fixings to also resist wind uplift loads.
- Position the first bracket at the high point as high as possible under the roof overhang. Screw the bottom slots in the bracket first as this allows for minor adjustments, and then fit the top of the bracket.
- Where possible, gutter runs shall be continuous from corner to corner within the 6 metre length limitation. Laps shall be formed to lap away from water flow direction and where possible away from the line of sight. All laps shall be positioned away from doorways and access ways. All laps must be sealed and riveted with no sealant build-up on the inside lap edge. For gutters supported by external brackets, it is good practice to position laps such that they are covered by a gutter bracket.
- Internal brackets should be positioned and fixed under the roof profile rib and not the pan or trough, to allow unobstructed discharge into the gutter avoiding the bracket.
- Gutter stop ends shall be formed wherever gutter runs are terminated, except where the termination occurs at a rainhead.
- Any exposed metal foot on the gutter brackets should be protected with a suitable durable paint system.
- Placement of downpipes must be to suit the roof catchment area for the flow capacity of that gutter size. Droppers must be positioned at the lowest point of the gutter run.
- There should always be an overflow outlet provided as a secondary means to allow water to discharge to the outside of the building, should a blockage occur or in heavy rainfall conditions beyond the scope of design. This must eliminate water from the gutter entering the building.
Gutter Brackets in Snowfall Areas
When installing gutters in areas subjected to snow fall in New Zealand, the gutter bracket spacings must be reduced and snow straps installed to take the increased snow weight that may be experienced during periods of snow fall to avoid damage to the gutter system.
This is a guide to the snow fall regions. Please refer to the standared AS/NZS 1170.3 for full details, available for purchase from www.standards.co.nz
| Island | Sub Alpine Snow Region | Height above sea level (m) | Region Description |
| North Island | N1 | 400 to 1200 | South of a line from Opotiki to Turangi and across to New Plymouth |
| South Island | N2 | 200 to 900 | West of Southern Alps from Nelson to Milford Sound |
| South Island | N3 | 150 to 900 | Nelson East to Cheviot |
| South Island | N4 | 0 to 900 | East of Southern Alps Cheviot to Moeraki into Omarama |
| South Island | N5 | 0 to 900 | South of Moeraki around to Milford Sound |
Note: Regions with a height above sea level greater than shown above require specific design and are outside Dimond recommendations.
Maximum gutter bracket and snow strap spacing (mm) for Dimond Gutters by Snow Region
| Dimond Gutter Shape | Gutter Bracket | N1 - Gutter brackets | N1 - Snow straps | N2 - Gutter brackets | N2 - Snow straps | N3 - Gutter brackets | N3 - Snow straps | N4 - Gutter brackets | N4 - Snow straps | N5 - Gutter brackets | N5 - Snow straps |
| Deep Quad | Internal | 600 | 900 | 600 | 600 | 600 | 600 | 600 | 500 | 600 | 600 |
| Quad SI | Internal | 600 | 900 | 600 | 600 | 600 | 600 | 600 | 500 | 600 | 600 |
| Box 125 | Internal | 600 | 900 | 600 | 600 | 600 | 600 | 600 | 500 | 600 | 600 |
| Box 125 | External | 900 | 900 | 600 | 600 | 600 | 600 | 450 | 500 | 600 | 600 |
| Box 175 | External | 900 | 900 | 600 | 600 | 600 | 600 | 450 | 500 | 600 | 600 |
| Box 300 | External | 600 | 900 | 600 | 600 | 600 | 600 | 450 | 500 | 600 | 600 |
| 150 Half Round | External | 900 | 900 | 600 | 600 | 600 | 600 | 450 | 500 | 600 | 600 |
Notes:
- Based on an 8m maximum single roof run
- Situations where upper roofs allow snow to fall onto lower roofs are excluded and require specifc design
- Each snow strap is fixed to roof and into purlisn using 2x 12 guage self-drilling screws or M6 Roofzips
- Each snow strap is fixed to the gutter using 2x 4.8mm diameter aluminium rivets minimum.
- Snow strap min. sizing to be 0.55m x 25mm
General Workmanship
The following comments are made as guidelines for designers to use when inspecting Dimond rainwater disposal systems during and after installation.
Dissimilar Materials
Care should be taken to ensure that incompatible materials have not been used. Where necessary, water run-off from dissimilar materials should be contained and discharged using compatible materials.
Drilling and Cutting
Where gutter lengths require cutting, only shears, powered nibblers or hand shears should be used to leave a cleanly cut edge.
Any drilling should be carried out well clear of other lengths of gutter. All drilling swarf should be removed from the surface of the gutter immediately.
Ponding
Gutters shall be laid with a positive fall to the outlet to avoid ponding. Any ponding that occurs may affect any material warranty.
General Appearance
Laps shall be formed to avoid the water flow entering them and where possible to suit the line of sight.
Sealants
Only neutral cure silicone sealants should be used.
Where outlets (droppers) are fitted to the sole of the gutter, sealant must not restrict the flow of water to the downpipe or hold unnecessary dirt.
All sealed joints must be mechanically fastened, and excessive sealant removed to prevent unnecessary dirt buildup.
Strippable Film
Protective films must be removed immediately upon product installation. Prolonged UV exposure will make removal difficult. The film must be removed from laps and difficult to access areas prior to final fixing in place. Strippable film must not remain in direct sunlight for more than half a day.
Scratches and Touch-up
Scratches that have not penetrated to the base metal (on prepainted material) and minor surface abrasions should be left
alone, as touch-up painting will become obvious in time.
Any product with heavy scratch damage (e.g. scratches readily visible from a 3-4 metre distance and that exposes the
base metal) should be replaced.
Copper Joints
These can either be Silfosed together or use copper rivets and sealant. Care must be taken to get rid of any spirits of salts by washing the joint thoroughly. Providing for expansion and contraction should be allowed for as detailed in the MRM Metal & Roofing Code of Practice.
