A5.1.2 Solar radiation
Solar Radiation related movement. The natural drying out of soils around a building is a process that occurs constantly from solar radiation. This can cause cracking to occur when one part of a building is more exposed to the sun than another and there are differential rates of settlement taking place. The part of the building which is most susceptible to the effects of solar radiation is its northern aspect Especially vulnerable are the northeastern and northwestern comers which receive the full morning and afternoon sun.
The symptoms usually occur in the form of diagonal cracks at the corners of the building. The cracks will tend to be wider at the top, while narrowing down to the bottom, see Figure 2. In straight walls with no openings, there is a tendency for the cracks to occur at a point a third of the distance along the wall. These cracks will fluctuate with seasonal variations although they will rarely, if ever, close up completely. The cracks that form in the foundations in summer will tend to fill up with particles of soil, and these arc then prevented from reclosing when the ground is wetted in winter. It is therefore unusual for the foundations to regain their original form.
