I live in a seven year old flat and along one wall where it joins to the main building, a crack always appears. I filled it in before with some Polly filler but it opened again. I did it again after this picture was taken using builders caulk which has worked for most of it, but I will need to cover again before sanding it. Should I actually be putting tape over it first before covering again? I don't want it opening right up and going through the process again if I have painted it. Can was probably about 6-7mm at the biggest part but mainly 2-4mm. Any advice would be much appreciated as this wall has driven me mad!
Thanks