Minimum Gutter Fall Nz

Appendix 1 gives rainfall intensities around new zealand and figure 16 provides a graph from which to determine internal gutter sizes based on a rainfall intensity of 100 mm hour.

Minimum gutter fall nz. 200 mm minimum gutter h3 cca treated plywood 17 5 mm minimum membrane to wrap bottom and sides of exposed timber metal lined gutters must have welded cross joints and a strip of roof underlay between the metal and the timber or ply. Minimum gutter slopes should be applied to all internal gutters so that. The minimal slope needed for proper gutter drainage is 1 25 cm 1 4 inch for every 3 metres 10 feet of gutter. Where the rainfall intensity exceeds 100 mm hour the minimum gutter cross sectional area based on roof pitch can be determined from the graph.

Your gutters have a high point and a low point. If the run has two downpipes then the high point should be placed between them. Every internal gutter must have at least one outlet and one overflow. Gutter fall all gutters must have a minimum fall of 1 500 2 mm in 1 m the cop recommends 1 200 5 mm in 1 m as it will improve drainage and self cleaning.

The difference in position between the two is known as the gutter fall. If the length of the gutter is 10 5 metres 35 feet the amount of slope required is 1 25 cm 1 4 inch multiplied by 1 metres 3 5 feet which when. Have a minimum fall of 1 100 have a minimum width of 300 mm be located to collect water draining across the deck be capable of managing the level of discharge for the deck area have no membrane laps within the gutter. The larger measurement of the two on a case by case basis should be taken.

The only mention of a required minimum slope for internal gutters in the compliance documents is in e2 as1 covering butyl rubber lined gutters where it requires a fall of 1 100. The high point is where the highest gutter bracket is placed and is the furthest from the outlet s. For internal gutters it is recommended that the proportion of base width to height be 2 1. A fall of 1 60 provides even better drainage.

If gutters slope too severely they don t hold water and water could splash over the sides in heavy rain. The gutter slope also called the pitch is the amount the gutter tilts down to let rainwater flow out of it. The amount of collected water increases until it spills over the sides of the gutter. In residential situations the minimum is 45mm.

E1 as1 has no minimum fall for internal gutters e2 as1 minimum fall must be 1 100 10 mm per metre which is often unachievable. The minimum recommended height for commercial internal gutters is 70mm or 1 60th of the overall length. Effect of gutter fall on drainage capacity. The cop calculates capacity of internal gutters with different degrees of fall this has a big effect on capacity.