A sectional blade for a wind turbine, the blade extending lengthwise between a tip and a root where the blade is attachable to a hub of a wind turbine, crosswise between a leading edge and a trailing edge, and thickness wise between a windward and a leeward outer surface. The sectional blade comprises a first blade portion and a second blade portion. The blade portions are formed as separate components and arranged to extend lengthwise in opposite directions from a junction where the blade portions join. The blade forms, in a cross section perpendicular to the lengthwise direction and through the junction, a maximum thickness location between the leading and trailing edges, the maximum thickness location being where the distance between the windward and leeward outer surfaces is larger than at any other location in this cross section. The sectional blade comprises an assembly board which is adhesively joined to an outer surface of both blade portions between the trailing edge and the maximum thickness location.