Roofs With Internal Gutters

Breaking down the pros and cons of flat roof drains.

Roofs with internal gutters.

Internal or within roof area gutters also known as box gutters can cause significant inconvenience damage and repair cost if water from the gutter gets into the building structure below. A drain at the top with a trap to catch debris connects to the internal water system where pipes drain it internally through the building. The built up and torch down roofing will last about as long as the average twenty year steep slope roof and the pvc tpo liners if installed correctly could last as long as the thirty year steep slope roof. Often the outlet to the valley gutter discharged over a small portion of roof before being contained by the eaves gutter figure 7.

This type is great for larger buildings and those that naturally pool at the center of the building. Internal drains some commercial roofs have drains like the drain in a shower. The internal gutter system is made up of a gutter lining material a metal drop scupper and a fascia board that has been installed more than two inches above the roof deck. Internal gutter construction gutter construction varied from a simple shallow trough or v like a valley detail to a tapered valley laid over firred framing to give a fall figures 5 and 6.

External downspouts mounted to collect water flowing from rooftop scuppers. Metal lined gutters must have welded cross joints and a strip of roof underlay between the metal and the timber or ply. Internal gutters must be continuously supported on timber boards treated to h1 2 or on ply treated to h3.