Peripheral Purlin Bridge Details in 2d AutoCAD, dwg file.
<p>This Architectural Drawing is AutoCAD 2d drawing of Peripheral Purlin Bridge Details in 2d AutoCAD, dwg file. Purlins are installed <strong>horizontally under metal roofs</strong>. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. Purlins are 2 by 4 feet and are installed much like metal roofing.</p>