Some of the walls in my house, have developed cracks, which are 2 to 4mm wide. One crack, runs diagonally, from floor level to about 80% of the wall height, and other cracks run along the window frames. The house is built on a concrete beam and column structure, but apparently the foundation in one corner has sunk a bit, due to heavy construction in close vicinity. The impacted walls, are not load bearing walls.
I am planning to paint my house, and wanted to fix these deep cracks prior to that. I've been told by few people that pressure grouting might be an acceptable solution, and wanted to check. Reading around the web, I see pressure grouting involving drilling big holes (about 2-3cm dia) in the wall, and grouting them, but couldn't figure out the purpose of doing so. Also, I've seen some photographs showing grouting attempts of the foundation itself by pressure-grouting deep holes near foundation. So, the process, and recommendations aren't clear.
Finally, does grouting / pressure-grouting require specialized tools, equipment and skills, or can one attempt this DIY ?
Edit: Forgot to mention that the cracks in question, appear on both sides of the wall, so it is not just a crack in the plaster-work.
Edit2: Building is not old - about 7 years. Cracks developed about 3 years back, and I think I've not seen them grow in the last 1 year.