Minimum Cill overhang

[bluebaron]

ive have upvc windows installed on my timber frame. They are fitted into the fire stop or in he cavity which is 50mm then external block 100mm and so I have around 25-30mm overhang on a 180mm Cill.

Problem now is I need to render so that's around 15-20mm which will leave me with a 10mm overhang which seems a bit tight to me.

Installer said it's normal to fit windows in timber frame this way but should I get him to move them forward onto the block to allow a better (30-50mm) overhang or just accept it?

Thanks

 

[Gazman16]

I was always taught 30mm minimum overhang from finished external surface but I don't know if there are actually any rules or regs on it.

 

[DHFrames]

Think it's 25mm on the GGF Installation Guide