It is very common to see shrinkage and movement of timber especially on new building work, and where renovation work has been undertaken. Over a period of several weeks and months, gaps begin to appear in timber door frames, window frames and skirting boards. This shrinkage is often most noticeable when the painting work has been completed during the wettest and coldest months of the year.
If the house has been locked up for any length of time after painting is completed, as the temperatures increase, and the building holds the heat, the timber will lose moisture content and shrinkage will occur. This shrinkage is often seen when heating is turned on, and the house is warmed through.
Timber shrinkage can also be seen on window frames and sills and takes the form of raised filler on the timber. As the timber shrinks the filler is forced up from the surface to form, often a dome shape.
For more information please see this Master Painters Fact Sheet: