Along with taking into consideration the scaffolding time, you should have a look at for how long your scaffolding can be erected for. http://www2k.biglobe.ne.jp/~kao-nori/jawanote.cgi?page=0&url=www2k.biglobe.ne.jp/~kao-nori/jawanote.cgi%3fpage%3d0%26url%3dwww.union.ic.ac.uk/rcc/fellwanderers/gallery/main.php%3fg2_itemid%3d125