A box gutter is defined as a graded channel generally of a rectangular shape for the conveyance of rainwater within the building footprint including adjacent to a wall or parapet.
Box gutter framing detail.
The details shown are for the lining of a wood box gutter frame.
Most box gutters consist of wood framing covered by a thin sheet metal lining made out of galvanized steel stainless steel copper or another metal that will not easily corrode.
Box gutters are deemed to satisfy the performance requirements of the national construction code if they are certified to meet.
Box gutters are essentially placed between parallel surfaces as in a valley between parallel roofs or at the junction of a roof and a parapet wall.
A box gutter is actually built into the bottom of the roof or into the roof overhang.
The box is built by an experienced carpenter into the roof overhang or into the bottom of the roof then lined with the sheet metal.
On this page you can find the pdf instructions for installation of a typical box gutter detail with the dryseal flat roofing system.
When lining a masonry cornice the edge strip can be secured to the masonry cornice with brass screws and lead shields 12 apart.
Clearance for downspouts through the wood framing is a minimum 1 2 all around.
The foundation of most box gutters is wood that is then covered with thin sheet metal such as tin copper lead stainless steel or some other metal that will not readily corrode.