 In later developments, most particularly in urban contexts, the log frame was then further covered in a layer of wooden planks.It is hypothesised that it was only from the 16th century onwards that wooden houses were painted in the familiar red-ochre or "punamulta", containing up to 95% iron oxide, often mixed with tar.The balloon framing technique for timber construction popularized throughout North America only came to Finland in the 20th century.