A box gutter, internal gutter, parallel gutter, or trough gutter is a

rain gutter A rain gutter, eavestrough, eaves-shoot or surface water collection channel is a component of a water discharge system for a building. It is necessary to prevent water dripping or flowing off roofs in an uncontrolled manner for several reasons ...

on a

roof A roof ( : roofs or rooves) is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of temper ...

usually

rectangular In Euclidean geometry, Euclidean plane geometry, a rectangle is a quadrilateral with four right angles. It can also be defined as: an equiangular quadrilateral, since equiangular means that all of its angles are equal (360°/4 = 90°); or a par ...

in shape; it may be lined with EPDM rubber, metal,

asphalt Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...

, or

roofing felt Bituminous waterproofing systems are designed to protect residential and commercial buildings. Bitumen (asphalt or coal-tar pitch) is a mixed substance made up of organic liquids that are highly sticky, viscous, and waterproof. These systems ar ...

, and may be concealed behind a

parapet A parapet is a barrier that is an extension of the wall at the edge of a roof, terrace, balcony, walkway or other structure. The word comes ultimately from the Italian ''parapetto'' (''parare'' 'to cover/defend' and ''petto'' 'chest/breast'). Whe ...

or the

eaves The eaves are the edges of the roof which overhang the face of a wall and, normally, project beyond the side of a building. The eaves form an overhang to throw water clear of the walls and may be highly decorated as part of an architectural styl ...

, or in a

roof valley A roof ( : roofs or rooves) is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of tempe ...

.Dictionary of Architecture & Construction, C.M.Harris.Glossary of Australian Building Terms - Third Edition.(NCRB) 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. They should not be confused with so-called valley gutters or valley flashings which occur at the non-parallel intersection of roof surfaces, typically at right angled internal corners of pitched roofs. Provision is made in the design of the gutter to have a rain flow to the outlet with a maximum slope of 1:200 and a minimum of 1:400.

Gallery of sketches

Note! The sketches in this section reference terminology commonly used in the UK and Australia. File:Parapet-box-gutter.gif, A section through a box gutter at the intersection of the bottom of a sloping roof and a parapet wall. File:Parapet-gutter.gif, A simpler box gutter arrangement at a parapet wall that give a bare minimum of compliance to the Building Code of Australia (BCA) File:Boxed-valley-gutter.svg, A box gutter between two parallel roof surfaces. File:Triangle-gutter.gif, A sketch of a now illegal gutter construction under the BCA. A design to be avoided.

References

External links

An Illustrated glossary of roofs and roofing terms.
Architectural elements Roofs {{architecturalelement-stub