Transoms or putlogs should be laid no more than 1.2m apart if used for supporting 38mm scaffold boards. If using 50mm scaffold boards then they should be laid no more than 2.6m apart. The actual length of the of the transoms or putlogs is determined by the width of the working platform, this width is determined by the by the intended use of the scaffold. Working platforms should have a minimum width of 600mm.

The main transoms are installed horizontally across the ledgers at right angles adjacent to each pair of standards. In some cases they maybe connected to each pair of standards. The purpose of the main transoms is to hold both rows of standards in position making the scaffold more ridged. They also act as a support for scaffold boards. Main transoms are usually installed in the direction of the smaller dimension of the scaffold.
Intermediate transoms are installed in between the main transoms acting as supports, sometime referred to as 'board bearers'.