Guard rails to boarded (Finished Lifts)
Guard rails are required to all scaffolding lifts (other than foot lifts) to prevent falls.
Guard rails are required to form temporary edge protection to scaffolding structures at both board lifts working lifts and none working lifts used during the construction of the scaffolding structure.
The guard rails are generally constructed by fixing scaffold tubes horizontally to the inside of the scaffold standards (uprights) to create the temporary edge protection. The guard rails are fixed to the outer (façade) and end face (return) of the scaffold, the guard rail tubes are fixed to each standard of the scaffold structure using right angle coupler. The guard rail tubes should be connected at a minimum of two points to prevent downwards and outwards movement of the guard rail. Cantilevered end guard rails fixed at one end are unsafe and must not be used. On a straight run of independent scaffold, it is permissible to fix the end guard rail with a single coupler at the outer standard position above the outer façade guard rail with the inside of the same tube fixed to the inner standard with a right angle coupler.
Guard rails must be installed so that the principle (top) guard rail height is measured at a minimum of 950mm to the top of the tube on both outer and end faces, this is measured from the decking forming the platform to the top of the guard rail. An intermediate guard rail must then be connected below the principle (top) guard rail so that the gap between the two guard rails and the gap between the intermediate guard rails and any toe board used does not exceed 470mm.
The principle (top) guard rail must therefore be between 950mm and approximately 1260mm above the decked platform if 225mm scaffold boards are used as toe boards.
All board lifts or sections of board lifts must be protected with double guard rails and toe boards (to prevent risks of falls to persons or materials). Additionally, guard rails or a combination of guard rails and toe boards may be required if risk of falls are identified such as to internal service gaps or if working above the height of the principle top guard rail.
(Source NASC TG20:21 Operational Guide)
You can download the PDF here.