Braathen Dendrokronologiska Undersökningar dates oak objects of an age within the time span from the present to the fourth century AD, and pine object as old as from the eighth century AD.

The dating of wood objects, such as buildings and wooden archeological objects, is done by the method dendrochronology. Dendrochronology is a scientific method of dating based on the growth of tree rings. The growth of tree rings, or growth rings, differs from year to year primarily dendent on climatic conditions during the growth season. By measuring the tree ring widths of the sample a unique series is established by which a precise dating can be concluded.

The dendrochronological project was started in 1973 in close cooperation with the archaeological project Lödöseutgrävningar (excavation of old Lödöse, western Sweden) and Riksantikvarieämbetet.

Approximately 10 000 samples have over the years been collected and analysed. The samples originates primarily from southern and mid Sweden, from Gotland and the Baltic area.