Squared timbers were used to support a flat Palestinian roof. In Jesus' parable of Luke 6: 41 REB uses ‘plank’ for AV ‘beam’, but ‘log’ of NRSV is misleading for English readers.
Citation for beam
Citation styles are based on the Chicago Manual of Style, 15th Ed., and the MLA Style Manual, 2nd Ed..
MLA
"beam." In A Dictionary of the Bible. Ed. W. R. F. Browning. Oxford Biblical Studies Online. May 19, 2013. <http://www.oxfordbiblicalcstudies.com/article/opr/t94/e237>.
Chicago
"beam." In A Dictionary of the Bible. , edited by W. R. F. Browning. Oxford Biblical Studies Online, http://www.oxfordbiblicalcstudies.com/article/opr/t94/e237 (accessed May 19, 2013).