you can get ridge clamp about £50 otherwise you bed on mortar, with tiled roof,and point up length of ridge and overhead,otherwise, slate to top an tail, meaning,put mortar at top and bottom of ridge,and point up on overhead of ridge,hope this helps, if you need further advice etc please feel free to contact below,JOSH
http://www.birminghamroofingrepairs.co.uk
josh, April 2008