Hover over the letters on the diagram for more details.
The description below will explain the calculation in more detail.
Floor to Floor height – record the vertical drop ( A ) between the floor in the upper room and the floor in the room below, including the thickness of floor boards, joists and ceiling.
Ceiling Height – Record the vertical drop ( B ) in the room below from ceiling to floor.
If you have horizontal clearance of ( CH ) over 7ft ( 2130 mm ) you don’t need to measure this one accurately – you have more than enough clearance.
Loft Clearance Arc – Most loft ladders will swing through an arc in the loft as they are raised and lowered. Record the horizontal distance to obstructions, measuring from the hinge end of the trap door ( C, CH )
D & E
Trapdoor Size – Record the clear length and width of your trap door ( D & E ).