Spouting & Guttering Calculator

This calculator works out how much spouting you need, along with the number of downpipes and brackets, so you can price a re-gutter or a new build in New Zealand without guesswork. Spouting, the New Zealand term for roof gutters, runs along the eaves to catch rain and carry it to downpipes, and getting the quantities right matters for both the materials order and the system's performance. Too few downpipes and the gutters overflow in heavy rain, which is common in our climate; too many and you waste money and pierce the gutter more than needed. As a rule of thumb, a downpipe is provided for roughly every 10 to 12 metres of gutter, and more where a large roof area drains to one run, while brackets to hold the spouting are spaced around every 600mm or to the manufacturer's specification. You enter the total length of roof edge that needs guttering, which you can measure off the eaves or estimate from the building's perimeter, and the spacing you want for downpipes, and the calculator returns the total spouting length, the number of downpipes, and the number of brackets. This gives you a clean materials list to take to the supplier and a basis to check a quote. For an accurate order, measure each run of eaves rather than relying on the floor plan, allow extra length for corners and joins, and remember that internal and external corners, stop ends and downpipe droppers are additional fittings. Always size downpipes and gutters for your roof catchment and rainfall; this is a quantities estimate, not a stormwater design.

Add extra for corners and joins. Downpipes and gutters must suit your roof catchment and rainfall. A quantities estimate only.