This product is designed to fit between 38mm thick trussed rafters or ceiling joists spaced at 600mm centres to provide a clear joist opening width of 562mm. If the roof design does not provide this joist opening width, a suitable opening must be formed. Trimmers must be installed across the ends of the frame. These must be spaced to give a clear opening length of 662mm.
Frame fixes with ten screws, three through each side and two through each end. Fit the loft access door after the ceiling has been plaster boarded and skimmed. The frame must be a good fit into the trimmed opening. Never try to force it into an opening that is too small. If the opening is too large use packers to ensure a good fit.