What does Crown Mean?

Definition of Crown in Construction
The crown of a board is the bend of a rafter, floor or ceiling joist, as the board stands on edge. The crown can be addressed by sighting down the board from one end to the other. The crown of a rafter or length of wood should always be installed up, as opposed to down. The board should always appear as it is smiling and never frowning. The proper orientation of boards of length is important when viewing the resultant surfaces of walls, roof panels and floors. In many framing applications the incorrect positioning of one rafter can make all the difference in the overall appearance of the finish product.

To install a board with the crown down, will cause the board to further sag or frown as loads are applied. Concrete beams, steel beams as well as laminate engineered wood beams are designed to have a crown or camber within them. The camber of the beam is positioned upward to allow the settling of the structural component when fully loaded. With proper structural engineering of the component, once the overall loading of the structure is completed, the structural component will lose its crown or camber and position as designed, this could be straight level or with a remaining crown. In almost all situations, the structural component will not go into deflection, if properly designed.