Support beam (5)

I believe the answer is:
joist
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">support beam</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for joist that I've seen before include "Beam supporting floors and roofs" , "Timber or steel roof or floor support" .)