Roof Overhang Or Parapet

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.

Roof overhang or parapet.

Historically so many problems have occurred with parapets that we have a name for it. 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. My flat roof has a fall in it and surrounding it all is a parapet that is probably 600mm high at its highest point. They re wall panels below the roof line that extend above the roof line to a given elevation.

On accessing the roof we noted a number of defects to the new section of roof which included. 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. A well designed roof overhang is much less likely to lead to rain penetration and will offer better weather protection to the underlying wall. 1 their major function today aside from confusing architects is to protect the edge of roof assemblies from wind uplift forces.

Poor falls to the roof deck and subsequent heavy ponding. Parapet walls which can be added to one or more walls differ from facades and mansards in that they have no projection. They are essential for framing and shading windows reducing splashback and getting rain to fall far enough away from the foundation. The assembly is straight forward but what complicates matters is that the roof needs to be vented.

Like any roof with batt insulation the venting is an important part of the system. Parapetitus they have a long history which of course is not always clear that allows me to embellish without threat of peer review reversal. Overhangs for each roofing profile. The roof was circa 300 square metres and the new section of roof accounted for approximately 25 of the total roof area.

Typically they are added at the high eave and both endwalls of a single slope building to hide the roof slope. 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. 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. Roof overhangs might look relatively routine but there is a lot of design thinking that goes into creating the optimal dimensions for each one.

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