What is a "Trimmer Joists"

Hello I am presently taking the advanced crawlspace inspection course and the term “Trimmer Joists” came up in the course. The "Trimmer Joists should be doubled with accesses greater than 4 dimensional feet. If someone could please explain/show a trimmer joist for me, that would be great. I did try the graphics library.
James McArthur



Try Google; https://www.bing.com/images/search?q="trimmer+joists&qpvt="Trimmer+Joists&FORM=IGRE
That should help.

Thanks for helping me out!

Only when it is more than 4’

R502.10 Framing of Openings Openings in floor framing shall be framed with a header and trimmer joists. Where the header joist span does not exceed 4 feet (1219 mm), the header joist shall be a single member the same size as the floor joist. Single trimmer joists shall be used to carry a single header joist that is located within 3 feet (914 mm) of the trimmer joist bearing. Where the header joist span exceeds 4 feet (1219 mm), the trimmer joists and the header joist shall be doubled and of sufficient cross section to support the floor joists framing into the header.

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Great post. In older homes the flooring around the stairway opening slope due to trimmers not doubled up.

30 years as a carpenter and this is the first time I’ve heard that term. Everyone always calls them doublers. Constructions terms vary so much, especially regionally, that sometimes you have to use some imagination to figure out what someone’s referring to.


The reference was made to “Trimmer Joists” on page 4 section 1 of the Student Course Materials section of the advanced crawlspace inspection course. Great answers thanks again fellows

Morning, Kenton. Hope this post finds you well.
I concur. Constructions terms vary a lot. Especially regionally. Migration, to which all families did and continue to do to this day, have a lot to do with it, as well as building practices, only being separated by how long you stay in that one place or region. Then slang becomes familiar/typical/usual.

“you have to use some imagination to figure out what someone’s referring to.”
Kenton. I stick framed in Rural Ontario and Rural Quebec. In Ontario stick framing was referred to as Crib Work.
In Rural Quebec, the working language was French. I was not fully bilingual but I could read blueprints and organize.
Personally, I pointed to items on the blueprints to understand what was being referred to. Example: Bridging was referred to as Saint Johns Crosses. Robbie. s’il vous plaît faire les croix de saint johns s’il vous plaît. Translated: Robert. Please make the saint johns crosses please. I pointed to floor joists on the blue prints. and the carpenter replied oui or nodded.

I was just starting out stick framing. I could read a tape measure, hammer nails in planks and was level on the level built my own carpenters tool carry. What really opened the door was my ability to read blueprints, organise the job site precisely, arrange the materials acquisition sheets, keep track of materials required for the following week and allocate workers responsibilities and troubleshoot. Any outside rural building projects from the city had to hire 60% of the workforce from that municipality, district or range. I think I was 27 years of age at that time. The union, OCQ, pulled my union cards for not transferring hours from Alberta. Many that knew me knew my work ethic and would hire me for rural work.

Thanks for the post, Kenton. Constructions terms/slang still continues.