Drains, Scuppers and Gutters – the pro’s and cons

The pros and cons of Drains, Scuppers, and Gutters.

Pros and Cons of Drains, scuppers and gutters
Drain Basins are the best for any flat roof


  • Debris collects through the strainer and blocks the flow of water very easily.
  • Unclogging a blocked drain needs professional people to do it.- costly
  • The roof needs to be cleared of leaves and debris daily to prevent water to collect around the strainer – Especially in the fall.
  • When drains are not maintained regularly on a commercial roof, it could cause the water to pond and put stress on the roof structure and ultimately collapse the roof.


  • Drain pipes are inside the building and therefore will not freeze during winter.
  • Drains can be placed strategically in many areas of the roof.
  • Inner drainage systems can’t be seen from outside.

Drains should be properly placed as to remove ponding water

The biggest problem with flat roofs is standing water. It is important to make sure that a roof is properly drained. If water ponds on a flat roof, it could lead to problems later on.

Most residential roofs are sloped to the edge and a gutter system catches the water. There are some residential roofs that are built like commercial roofs and more likely have an inner drain system.

The position of Internal drains are crucial and should be located where water ponding occurs
It is best practice not to place drains near skylights

Gutter Systems


  • Cheaper to install than inner drains
  • Even if a gutter is full of debris, water can still sill over.
  • Debris tends to flow off the roof with the water.


  • Gutter systems need a lot of maintenance.
  • Leaves block downspouts easily.
  • Esthetically not pleasing – gutters and downpipes are eyesores on a building.
  • Downpipes and gutters freeze up during winter
Gutters on flat roofs need maintenance - leaves constantly fill gutters up
Gutters collect leaves and stop the flow of water


Scuppers are a very effective way to channel water off a roof. The best is to have a wide scupper, 12″ or wider so leaves and debris will wash through the scupper instead of clogging it.

Scuppers can let the water drop off the roof to the ground or can lead into a gutter system. Many times the problem will come when a leader pipe or leader header gets clogged due to debris and leaves. Winter weather can also freeze a gutter or downpipe and cause the scupper not to function properly.

The best system would be to let the scupper drop the water over the edge of the roof.

Scupper let water off the roof free flowing
This is a scupper. Scuppers allow water and debris to flow freely of a roof
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