Wall Heights - Pryda vs Mitek

We are starting to resolve the wall-height issues. There are two major software vendors in Australia for wall framing and truss design - Pryda vs Mitek. One of the companies using the Mitek software for design have declined to quote on the basis that they can't design a wall for wall-heights over 3000mm. However, two companies I have rung that use Pryda software say that can design, build and deliver the pre-fabricated 3600mm wall frames (and trusses). One company that uses Pryda software could design it, but not build it, as their jigs cannot work with sizes over 3000mm.

Note that the Pryda design software is available from http://www.pryda.com.au/. I was sent this on CD-ROM and have now installed it to do an initial "sanity check" on the wall frame design.

With our tiled roof (85kg/m2), 27.5 deg pitch, with a "RLW" of 3.6m (roof load width - approx equal to length of one truss top-chord), then the Pryda software is saying that the common studs in the wall should be minimum 90x35 F8 SSW not-notched (pine). For notched-studs, we need minimum 90x45 F8 SSW notched (pine). Note that we have a fairly small RLW, as the roof design calls for internal load-bearing walls. Over the 14.4m width of the house, this implies an RLW of approx 14400/4 = 3600mm.

On this basis it seems unlikely that we will need 120 common studs in the external walls (as was suggested by one of the wall-frame manufacturers).