Repointing is the process of repairing or replacing the external mortar joints between masonry units on a structure or building. 

Here are some reasons why you may need to repoint your house:
1. Water Damage: Over time, weather and moisture can cause mortar joints to crack or deteriorate. This can allow water to absorb into the wall, causing damage to the structure of the building.

2. Appearance: Repointing your house can improve the appearance of your home. Over time, the mortar can become discolored, making the building look old and worn.  Repointing your brick or stone house will give your home a new and clean look.

3. Safety: If the mortar joints are in a really bad condition, they may pose a safety hazard. Loose or deteriorated brick and stone can fall, possibly injuring someone or causing damage to someone's property.

4. Energy Efficiency: Repointing can improve the energy efficiency of your home/building. When gaps are present in the mortar joints, air can enter and escape from your building making it more expensive to heat or cool the dwelling.

5. Pests: When there are gaps and small holes present in pointing, insects and rodents can enter your home or nest in the small gaps. 
Repointing can help prevent small rodents and insects from entering your home.