The original pine timbers did not split as do the modern timbers. Why? Because the process of creating timber for the stave was to: find a really big tree, cut the top and large branches off and leave it for 10-15 years. This caused all the sap to be drawn back into the tree. Then cut it down and leave it for another year, then build a church. None of the older timbers split. Modern timber is kiln dried and splits.
The inside of the Heddal church is decorated with patterns, the original catholic scenes being painted over after the Reformation when Norway became Protestant. There are no windows and originally there were no benches. The bells from this church had to be removed to a separate bell tower in the mid 1850s after the weight started to pull the walls inward.
Later we saw another Stave church at Eidsborg as we happened to drive past. it is one of the best preserved and still a local church.