1) It can mean a roof rafter, as in Henry Best’s description of a thatcher at work.
1642 They … fasten the bottles [bundles] to the sparres, Elmswell. In many early Yorkshire references though it was a pole or piece of timber, typically fir imported from the Baltic, and under six inches in diameter: 1357 Item, pro v sperris emptis, ijs vjd, York
1409 pro sparres cum cariagio, Beverley
1463 2 c fyrsparres, Hull. Later, it was used of home-grown timber: 1614 twenty sparres of oake wood, value 20d.