Flat Roof Eaves Construction Details

As well as the small selection of roof detail drawings shown here many of the building notes have a related construction detail drawing with specific dimensions eg rafter sizes spans insulations types for purchase with the building specifications.

Flat roof eaves construction details. Before manufactured trusses the simplest roof construction involved extending exposed rafter tails beyond the walls of the house. Additional construction details drawings. Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls. The wallplate is secured to the internal wall separated by dpc.

The wallplate is then used to secure the rafter to. If a sprocketted or bell cast detail is used then eaves courses should beno lower than the minimum recommended roof pitch. The design of your eave is dictated by the construction of your roof. To determine exactly what the rafter tail will look like i always make a full size drawing on a scrap of plywood of all the eaves elements including framing and finish materials see illustration above.

Fix a rafter spacer tray to provide a clear air path between underlay and insulation. The construction of the flat roof is similar to that of the timber upper floor. With flat clay roofing tiles the first course may be raised with a special starter tile as shown at left in figure 2 27 or by a metal eaves closure raised fascia or wood cant strip. With a cant strip or raised fascia a beveled wood or foam antiponding strip is required to prevent ponding of water along the eaves figure 2 29 below.

Fix a plywood board or proprietary tray to provide continuous support to underlay to prevent water retaining troughs. Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading. The eaves detail shows where the roof members and coverings meet the wall of the dwelling. The cavity is closed with a proprietary cavity closer.

Trusses streamline construction but it s important when using them to make sure the resulting eave works with the design of your building. This modest slope can be achieved in a number of ways. Flat roofs are built with a slight pitch of at least 1 8 per foot so water can drain either to centralized drains scuppers or a gutter system. From there the flat roof system you choose will determine the materials you apply.