Roof Rafters And Ceiling Joists

Ceiling joists are horizontal members used with rafters and roof joists.

Roof rafters and ceiling joists.

Roof rafter span use this table to determine the maximum lengths of roof rafters based on species and grade of lumber spacing dimensions load and slope. Ceiling joists can be on both low sloped roofs and high sloped roofs and help to prevent racking and spreading of your rafters or walls which could lead to sagging. They are important load bearing structural elements. Roof joists may span continuously from one side of the house to another or may be supported on an interior bearing wall.

Similarly ceiling joists are the planks of wood that create the flat surface of your attic floor or top story ceiling. Their functions are similar to rafters. For example cathedral ceilings built with 2x12 rafters have space for standard 10 inch batts r 30 and ventilation. This can be achieved through the use of truss joists scissor truss framing or sufficiently large rafters.

Floor joist span use this table to determine the maximum lengths of floor joists based on species of lumber joist spacing and joist size. This board forms the bottom member of each rafter and of course the ceiling of the space below. Span calculator for wood joists and rafters also available for the android os. Roof joists are found on low slope roofs slope of 2 in 12 or less.

A structural ridge is the standard alternative to ceiling joists. The are similar to trusses in this regard. In unfinished space an attic insulation is typically laid between the joists. Also available for the android os.

They are nominally 2 inches thick actual width usually 1 1 2 inches and come in a variety of widths from 8 to 12 inches. In order to maintain the triangle shape there are specific requirements for how to fasten the corners of the triangle together. Joists are traditionally made from timber. In this design the tops of the rafters attach to a load bearing ridge beam that runs along the length of the roof.

They may carry ceiling loads. Cathedral ceilings must provide space between the roof deck and home s ceiling for adequate insulation and ventilation. Meeting current irc roof framing requirements means builders are really constructing very simple triangles using the rafters and ceiling joists because triangles are known to be the most stable shape.