Is the wood part ceiling joist

per wiki,

A joist is a horizontal structural member used in framing to span an open space,

often between beams that subsequently transfer loads to vertical members.

This tutorial mentions ceiling joist.

Is the wood part pointed out by red arrow (img_1) the ceiling joist?

consider the following image (img_2), is the part pointed out by blue arrow a ceiling joist, the red one another ceiling joist?

Consider the following image (img_3), which comes from wiki.

there are 2 lay of joists, one is for ceiling, the other is for floor, is my understanding right?

• So where does the rest of it go? You should be able to tell by how it is supported and what it connects to... Jan 29, 2020 at 10:09
• Neither of the sketches show a clear idea of a joist doubling or in other words, acting as, a ceiling joist and floor joist. Regarding img_3, if the lower joists in the sketch had a living space under it and not a crawlspace, those joists would work or act as or double as ceiling and floor joists. If the upper joists in the sketch clearly shown walls and another set of joists, then that set of joists purpose would act as floor joist for the second floor and the same joist would act as ceiling joists for the first floor.
– Jack
Jan 30, 2020 at 4:21
• @Jack Would you please give a link that show a clear idea of a joist doubling? Jan 30, 2020 at 5:58
• Please understand this is not referring to 2 different joists, but one joist, because of where it is placed in the house is serving 2 different purposes. As in double purpose. Doubling is a past tense American English term to describe one object that serves 2 purposes
– Jack
Jan 30, 2020 at 6:45
• Here is a link which you may find helpful. awc.org/pdf/codes-standards/publications/wcd/… Figure 1 pg 17, figure 2 page 18 and figure 6B on page 21 are examples of joist acting as floor joists and ceiling joists simultaneously, "doubling" or perhaps "doubles" as it was called. Figure 6B is the best example since it clearly shows drywall on the ceiling of the basement, also shows that there is a floor surface on the upper side of the same joist.
– Jack
Jan 30, 2020 at 6:57