A method for forming double-aligned stacks of timber where the pieces of timber are transported along a pathway perpendicular to their longitudinal direction on an endless transport means (10A, 10B, 10F) in the form of chains or belts, whereby in one of a number of steps that follow one after each other, the pieces of timber are end-aligned through being displaced in their longitudinal direction against end stops (37, 38), and which pieces of timber having been formed into a layer with a width that corresponds to the pre-determined stack width are formed into a stack through the layers being stacked on each other, with, in some cases, the intermediate insertion of laths, wherein the method includes the following operational step: - that in a first step pieces of timber that have been fed forward are caused to form a contiguous layer in which the number (n) of pieces of timber in the layer is controlled using information about the pre-determined stack width, the method being characterized in that further includes the following steps: - that in a second step the pieces of timber in the contiguous layer are separated from each other through a slit with a pre-determined width (b) being, formed between neighbouring pieces of timber in the layer, - that in a third step the separated layer is divided into a number (n) of pre-determined sublayers (20:1-20:n) where each such sublayer includes a pre-determined number (n') of pieces of timber, - that in a fourth step the number (n') of pieces of timber that are in each sublayer (20:1-20:n) are end-aligned uniformly within the sublayer through being displaced in the same direction in their longitudinal direction against a first end stop located on one side of the transport pathway, - that in a fifth step the number (n') of pieces of timber that are in at least one of the sublayers (20:1-20:n) is end-aligned uniformly within the sublayer through being displaced in the same direction in its longitudinal direction against a second end stop located on the opposite side of the pathway, - that in a sixth step the relevant sublayers (20:1-20:n), each including a number (n') of pieces of timber, are brought together such that the pieces of timber return to form a contiguous layer, - that in a seventh step layers that have been reformed in this way and having contiguous pieces of timber are stacked on each other, with, in some cases, the intermediate insertion of laths, in order to form a stack of timber. - that in a first step pieces of timber that have been fed forward are caused to form a contiguous layer in which the number (n) of pieces of timber in the layer is controlled using information about the pre-determined stack width, the method being characterized in that further includes the following steps: - that in a second step the pieces of timber in the contiguous layer are separated from each other through a slit with a pre-determined width (b) being, formed between neighbouring pieces of timber in the layer, - that in a third step the separated layer is divided into a number (n) of pre-determined sublayers (20:1-20:n) where each such sublayer includes a pre-determined number (n') of pieces of timber, - that in a fourth step the number (n') of pieces of timber that are in each sublayer (20:1-20:n) are end-aligned uniformly within the sublayer through being displaced in the same direction in their longitudinal direction against a first end stop located on one side of the transport pathway, - that in a fifth step the number (n') of pieces of timber that are in at least one of the sublayers (20:1-20:n) is end-aligned uniformly within the sublayer through being displaced in the same direction in its longitudinal direction against a second end stop located on the opposite side of the pathway, - that in a sixth step the relevant sublayers (20:1-20:n), each including a number (n') of pieces of timber, are brought together such that the pieces of timber return to form a contiguous layer, - that in a seventh step layers that have been reformed in this way and having contiguous pieces of timber are stacked on each other, with, in some cases, the intermediate insertion of laths, in order to form a stack of timber.