12 Tips for better metal roof plumbing performance

Defective roofing & storm-water plumbing, and especially construction that involves box gutters, can create costly and hard to fix problems, and cause extensive water damage to buildings. They are one of the most common defects I encounter on new and existing build sites. The points below will go a long way to ensuring that your metal roofing system is complaint to AS3500.3;

 1.      the throat of the box gutter into the rain-head is the full width of the box gutter.

2.       the rain-head is completely sealed to the box gutter.

3.       the box gutter has a provision for overflow to discharge to the atmosphere as per the attached VBA guidelines.

4.       the box gutter has a fall of between 1:200 and 1:40.

5.       the box gutter discharges at the downstream end without change of direction.

6.       the box gutter is straight without change of direction.

7.       parapet cappings have a min 3 degree pitch back into the box gutter.

8.       spreaders do not discharge onto flashing and discharge in the direction of the roof fall.

9.       metal deck roofing is installed to the min pitch as per the manufacturers guidelines and turned down into the gutter to create a drip lip and turned up at the non discharge end.

10.   Sarking or insulation is trimmed back from the gutter to prevent moisture wicking into roof cavity

11.   If quad gutter has no overflow slots, 10mm packers are required between the facia and gutter to allow for overflow.

12.   Downpipes are required every 12lm of gutter max, and every 15msq of roof catchment area.

If you are a plumber that has any concerns regarding the carpentry work that has been carried out prior to installation of metal roofing components, do not proceed with works and contact the site supervisor