Abstract: A portable, collapsible brace for mounting scaffolding on the side of a building, comprises a generally "U"-shaped structure made up of two bent arms, each comprising an upright, surface-engaging section having an oblique section at its lower end. The upright sections are spaced from each other by a standard building wall stud spacing and can be nailed to the studs. The oblique sections are connected to each other at a point between the stud locations. An arm is pivotally connected to this point, and is removably engageable with a platform pivoted to the upright sections. The platform is also generally U-shaped, and nests inside the attachment arm structure in coplanar relationship therewith when the apparatus is collapsed.