Flat Roof Parapet Wall Construction

The construction of the flat roof is similar to that of the timber upper floor.

Flat roof parapet wall construction.

Slope the top of them inward so they don t stain the building façade. To keep water from pooling at these inside corners tom rips 2x4s lengthwise on a 45 degree bevel with a table saw. On two sides the roof abuts a parapet a short wall common around flat roofs as well as a wall for the third floor. Make sure that there is a waterproof membrane under the coping.

Parapets shall have the same fire resistance rating as that required for the supporting wall and on any side adjacent to a roof surface shall have noncombustible faces for the uppermost 18 inches 457 mm including counterflashing and coping materials. Because parapet roofs are encircled by walls they are more prone to leaking than traditional pitched roofs. Metal and stone copings leak at joints. Parapet walls can be constructed using different materials like reinforced cement concrete steel aluminium glass etc.

Furthermore parapets are often inadvertently connected to interior space via balloon framing gaps in structure or penetrations for wiring and mechanicals introducing warm moist interior air into the assembly and potential condensation. Some plain parapets come with an added coping or corbel to help bear structural load but most of them are simply flat extensions of the wall below the roof. Flat roofs of this type are usually finished in steel roof sheet and fall towards a special type of gutter called a box gutter. Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading.

This video is about making a transition form a flat roof to a parapet wall with taracotta clay caps. A parapet wall is a low or dwarf wall built along the edge of the roof terrace walkway balcony etc. Unlike standard exterior walls parapet walls are exposed to the elements on three sides. The easiest thing to get right about parapet construction is to keep rainwater from getting into the top of them.

The most common type of parapet seen nowadays is the plain parapet which is simply a basic flat wall extension. The principles are easy. Here the rubber roof will need to run up the walls and glue to the sheathing.