Happy New Year everyone!
I know it's a bit late in the day to add to this discussion, but I would like to point out that:
(1) joists are (by definition) always horizontal; therefore the word horizontal is not required.
(2) also, some people might prefer to say "wooden joist" instead of "wood joist".
I would not like anyone to think that English is by nature a verbose language; 2 words are required in this case to replace 1 in Greek, but only 1 if you say "joist" by itself (joists can be made of steel, when they are usually called "RSJs", meaning "rolled steel joists").
Can λατάκια be made only from wood?