Box Gutter Overflow

Outlets box gutter outlets must discharge through either a rainhead or sump.

Box gutter overflow.

If the box gutter has no overflow provisions this causes a waterfall over the sides of the box gutter typically running down the walls. Eaves gutters should have a minimum slope of 1 500 a fall of 2mm every metre. The pitch and tilt of your gutters make all of the difference. Making the box gutter wider will also reduce the box gutter depth.

As a box gutter is usually located above a room or space in a building there is an increased risk that rainwater overflow could cause damage to the building or cause loss of amenity to its occupants. Height of overflow weir above the bottom of the box gutter loc from fig i6a. Because of this increased risk a box gutter must be able to cope with a 5 minute duration rainfall intensity and a 1 in 100 year. The gutter s floor at the high point must be lower than gutter s lowest wall at the low point to allow excess water to drain over the high point to the neighbouring downpipe.

Support the entire weight of the gutter and sumps when full of water as well as a trafficable load at any point in the gutter and sumps. Trial box gutter width. If the gutter is tilting away from your house it could be causing an overflow particularly during heavy storms. The pitch of gutter heading towards a downspout can also cause overflow if it s too steep.

Due to differences in the freeboard requirements in this instance the deepest box gutter is required and used in the program. You can find these precut gutter splash guards about 3 in brown and white aluminum at a home center but you could easily make your own out of aluminum or sheet metal and spray paint them to match your gutters. Overflow provision for box gutters october 2014 the vba has identified several instances of plumbing practitioners failing to install appropriate overflow provision in box gutters and rainheads. Overflow box gutters must have independent overflow provision discharging to the atmosphere.

All domestic box gutters must be a minimum of 200mm wide and 75mm deep. The outlet of the box gutter may be blocked by debris or the box gutter outlet simply cannot discharge the water fast enough. It sounds like you have an overflow situation. Plumbers are reminded that roof drainage systems need to be designed and installed with appropriate overflow provision.

A wider overflow needs less depth of overflow hence the box gutter depth will also be reduced. Rainhead overflow or specific box gutter overflow must be at least 30mm below the height of the back of the box gutter. The box gutter depth and the sump length are influenced by the size of the overflow. Holes through the splash guard and the gutter.

The high point determines the gutter s fall slope and the roof area that each downpipe harvests. However a wider overflow may increase the length of the sump. Note it is possible in a wide box gutter for the depth to be shallower than for box gutters with a free outfall. This effectively states that all box gutters must allow for 30mm of freeboard which is from the overflow point eg.