Interior walls Posted by admin on June 16, 2013 Posted in: blog / news. Tagged: builders, extension, gaydon, m build, stud work, Walls. All the interior timber stud walls are up. All stud for the interior walls is all made on site rather than prefab. 4×2 studs, full fill insulation and then 12.5mm plasterboard. Roof trusses are also starting to go on.