It seems the general rule of thumb is to measure the opening from brickwork to brickwork in three places, use the smallest measurement and deduct 10mm to allow for the frames 5mm tolerances and for squaring up with a level.
However, what if the walls are rendered? Should the window be slightly bigger than the opening to allow it to butt against the inside edge of the render?
Any advise on measuring the height of a window which has existing external tiled sills?
However, what if the walls are rendered? Should the window be slightly bigger than the opening to allow it to butt against the inside edge of the render?
Any advise on measuring the height of a window which has existing external tiled sills?