Yes, providing more suitable equipment cannot be used because ladders are a last resort and should only be used for low risk, short duration work. Where ladders are used, they need to be of an industrial grade, in good condition and secured to prevent movement. The anchorage at the top of the roof ladder should be by some method which does not depend on the ridge capping, as this is liable to break away from the ridge. The anchorage should bear on the opposite slope by a properly designed and manufactured ridge hook or be secured by other means.
For more information, see [Advisory Committee for Roof Safety ](http://www.roofworkadvice.info/).