If there are gaps in the wall of the house, then this leads to drafts, leaving the house warm in the cold season. But the biggest danger is that the cracks grow in size over time, which further leads to the complete destruction of the wall itself. Even if a tiny crack appears, then after moisture gets into it and a constant change in temperature, it will collapse and grow. If the heat is leaving somewhere, but you cannot find a gap, then light a candle, and by the deviation of the flame, you can determine exactly where the gap is located. By the way, to save your house, you will also need thermal insulation and waterproofing of the foundation of your house.
Most often, cracks appear near the window and door opening, near the communication input. Tools such as silicone mastic and a special gun will help you get rid of these holes. But mastic will not help if cold air is blowing from the underground. In order to cover up the gaps between the floor, walls and baseboard, you can use a material such as neoprene. This material is very elastic in its structure and therefore is the most suitable for this purpose. Neoprene is also great for sealing cracks in walls. And after sealing, the wall can be treated with plaster and mortar. Try to putty the cracks in the dry and warm season so that the surface does not freeze.