Structural Timber Flat Roof Construction Details

Some observers suggest it s harder to replace a flat roof than a traditional pitched shingle roof because of the labor required to remove its layers especially on older flat roofs.

Structural timber flat roof construction details.

But now flat roofs often are constructed with fewer layers because of improved waterproofing technology. Flat roofs are hard to replace. Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls. For additional stability you can also use steel joists that are built into one or both of the walls.

This will give additional stability to the roof structure. Flat roofs of this type are usually finished in steel roof sheet and fall towards a special type of gutter called a box gutter. Collar ties rafter ties tension beams structural ridge beams. Part b structure investigates the structural aspects of flat roofs.

The construction and allowable load provisions of sections 2306 3 4 and 2306 3 5. This could mean flat roofs may not raise the same red flags they used to. On a basic level flat roof construction comes in the form of roofing timbers or joists as they are more commonly known or steels that are laid across two uprights walls in most cases. 2306 4 3 particleboard shear walls.

This article describes and illustrates the different types of support that prevents roof sagging and wall bulging at buildings including definitions of collar ties rafter ties and structural ridge beams. The basic construction of a flat roof starts with roofing timber that is laid across two upright items usually two walls. Some of these can support the roof and prevent ridge sagging and wall spreading. Pre manufactured roof trusses come in a wide variety of styles.

The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure. Timber trusses also are built in a variety of styles using wood or metal joints. Yet for historic modern style buildings like this old house s cambridge tv project flat roofs are at the core of the architecture meant to reflect the broad horizontal lines of the natural landscape. The design shear ca pacity of particleboard shear walls shall be in accordance 2003 international building code 467 wood table 2306 3 1 continued recommended shear pounds per foot for wood structural.

Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading. Besides the various loads acting on the flat roof the chapters of this section discuss potential primary structures and. Heavy timber rafters typically spaced 240 cm 8 ft to 370 cm 12 ft apart are called principal rafters. Flat roofs aren t architecturally logical as rain and snow will shed much more quickly off a sloped roof.