Cracking around openings

  • Building Design Expert
  • 4 years ago

One of the most common refurbishment or alteration tasks is the walling up of a window, or door opening that is no longer needed, or just doesn’t work with the new building layout. But is it a case of simply filling in the hole with a suitable material, or could there be a little more to it than that?

Such instances in construction produce the classic situation of straight line joints across more than just one masonry module – brick, or block. But the principles are the same whatever materials are employed. It’s all down to recognising a situation where supporting backgrounds to a common external finish, such as plaster or render, have a straight line joint between them, rather than a bond.

Building materials, whatever, their make-up, composition, or manufacture, will always be subject to movement due to temperature and humidity variations. With those same variations different materials will also react, or move at a different rate. So, plaster over a straight joint formed by the masonry infill of a window opening and the original surrounding wall, and watch the weaker material (the plaster) crack along that joint line. It will always, always happen. You will have heard the expression that the only certain things in life are death and taxes; well please add “cracking to finishes that span a straight line joint between backgrounds” – to give a more complete picture.

Make sure your sound system is is on, click the enlarge button and then click play to watch and listen to the pen cast below.