Roof Overhang Or Parapet

My flat roof has a fall in it and surrounding it all is a parapet that is probably 600mm high at its highest point.

Roof overhang or parapet.

Historically so many problems have occurred with parapets that we have a name for it. Flat roofs come in many shapes and sizes which include parapet roofs roof decks and green roofs to name just a few of the options available. On accessing the roof we noted a number of defects to the new section of roof which included. Poor falls to the roof deck and subsequent heavy ponding.

Flat roofs can be used to create box shapes cantilevered into daring overhangs or can be planted to create usable vegetated gardens. A well designed roof overhang is much less likely to lead to rain penetration and will offer better weather protection to the underlying wall. The assembly is straight forward but what complicates matters is that the roof needs to be vented. Consider alternatives to using a parapet because of the high risk of failure when compared with other possible options if this guidance is not followed.

Typically they are added at the high eave and both endwalls of a single slope building to hide the roof slope. The roof was circa 300 square metres and the new section of roof accounted for approximately 25 of the total roof area. Overhangs for each roofing profile. A parapet roof is simply put when a building s outermost walls extend upwards past the roof around the edges most often by a few feet.

They are essential for framing and shading windows reducing splashback and getting rain to fall far enough away from the foundation. For example corrugated sheeting has a 100mm maximum overhang when unstiffened and 200 to 300mm depending on wind load category and steel grade when stiffened by the attachment of a continuous supporting. While a roof parapet wall may seem like a small detail in the grand scheme of the entire building design it can actually change the dynamic of an entire roof both in terms of cosmetic detailing and safety. Normally you would find the venting at the soffit the underside of the roof overhang but that s not possible with the parapet.

The cladding profile should be installed so that any water runs back in to the flat roof and out through one of the internal gutter outlets rather than down the outside. Parapet walls which can be added to one or more walls differ from facades and mansards in that they have no projection. Roof overhangs might look relatively routine but there is a lot of design thinking that goes into creating the optimal dimensions for each one. They re wall panels below the roof line that extend above the roof line to a given elevation.

Failed lap joints to the deck and the parapet wall up stands.