DIY Doctor UK DIY Forums

Posted: **Sun May 13, 2007 10:18 am**

HI, AM NEW TO THIS FORUM AND WOULD LIKE TO KNOW IF 18MM BOARDS ARE NEEDED ON A FLAT ROOF IF IT WILL NEVER BE STOOD ON. THANKS FOR ANY HELP, DENNIS

Posted: **Tue May 15, 2007 11:30 am**

18 or 22mm, preferably 22. Its not just about standing on them its also about movement through expansion and contraction and possible snow loading.

BOARD THICKNESS