through the hollow portions 62 in another aspect a flexible assembly tab or member such as tab 28 32 and 128 may be provided on the boards near the tongue and groove region to provide a firm frictional contact between the adjacent tongues and grooves and to align the boards during assembly initially at points of contact between adjacent tongues and grooves of adjacent boards a bumper protrusion may be provided on one board which will frictionally engage with a complimentary groove on the other board it is also noted that tabs 28 32 and 128 provide a stop feature during the assembly process but further allow for lateral expansion and contraction of the boards during temperature extremes the tabs 28 32 and 128 may be referred to as flexible members the resilient or flexible members may provide for alignment and frictional engagement they may thus be in a slightly bent configuration in the assembled state however the tabs may also be sacrificial in that they are designed to be breakable or frangible that is they may break off upon application of sufficient force during installation of adjacent boards fig1 d shows a decking board having a different cross section from fig1 a this board 112 may be thought of as having a tongue 114 which projects into a groove 124 an upward facing channel 116 is provided that will function similarly to the channel 16 described above.