crack on internal walls

[StevenHu]

Hi

My house is about 20 years old. In one of the bedrooms on the 1st floor, I found a couple of small hairline cracks (less than 1mm wide): one is below the window sill, and others at 2 walls meet or the wall and ceiling meet. I have two questions: 1 is this merely a cosmetic issue rather than something more serious (structure wise)? 2 how do I repair/patch it. I would appreciate any advice.

Thanks a lot!

 

[misterhelpful]

Those are just typical settlement cracks so don't worry. Use caulk to fill the ones in wall/ceiling corners - it is flexible and should withstand any further movement - smooth it off with a wetted fingertip or sponge. Use a small knife or edge of a scraper to slightly widen the crack(s) under windows and then fill with a good quality ready mixed filler (Polycell or Toupret), allow to dry and sand smooth before re-decorating. Trying to fill hairline cracks without widening them first doesn't usually allow the filler to get in deep enough, meaning the crack will often re-appear somewhere down the line.