Wood Frame Flat Roof Assembly

This is located in a mixed climate northern california.

Wood frame flat roof assembly.

Hi i m an architect looking for advice as to how to detail a wood frame flat roof parapet wall assembly. By flat i mean one one that is sloped to drain and either is topped with a built up roof membrane or a single ply membrane. At the highest point of the sloped roof the parapet is about 10 tall at the lowest point the parapet is about 14 tall. To frame a roof start by choosing a roof style like a frame or gabled.

Closed cell spray polyurethane foam ccspf at bottom of roof sheathing. If less analysis is required. The assembly is straight forward but what complicates matters is that the roof needs to be vented. When framing a flat roof you will need to create a slight incline.

R value of ccspf to be 40 of total assembly. Acceptable if above is not feasible. Ci to be installed in multiple layers to limit insulation by pass from gapping of insulation. You can do this with a foam layer that exactly fits your roof.

Some roofs actually slope in several directions ensuring optimal water runoff. Other flat roof components underneath the basics flat roofs are usually constructed with a ceiling nailed to joists which support a deck usually wood in residential construction a vapor barrier insulation and a roof board. Chapter 7 ceiling and roof framing 40 ceiling joists 40 flush ceiling framing 42 post and beam framing 42 roof slopes 44 flat roofs 45 pitched roofs 45 valleys 48 dormers 48 overhangs 48 ridge beam roof details 49 lightweight wood roof trusses 49 chapter 8 wall sheathing 53 types of sheathing 53 corner bracing 54. Wood framed sloped roofs have been a common means to provide shelter and protection from the weather for centuries but high performance building enclosures often focus on wall designs rather than roof designs.

For the past 10 years energy code cycles have focused on wall assemblies. I looked for one on this website and there isn t one. This will help you create a flat roof framing plan. The parapet itself is standard wood framing with an applied siding in this case t g 1 4 cedar.

Then gather your measurements by calculating the run rise and length of each rafter segment in feet and the pitch of your roof in inches. Flat roofs are always built at a slight incline at least 1 8 inch per foot.