The Science Behind Breathable Walls & Why It Preserves Masonry

The Science Behind Breathable Walls & Why It Preserves Masonry

Masonry has always relied on a simple but powerful principle: walls must be able to breathe. Breathable walls allow moisture to move in and out of the stone or brick, rather than becoming trapped inside. When moisture is allowed to escape naturally, it reduces internal pressure and helps prevent cracking, spalling, and deterioration that can slowly develop within your historic masonry home.

Traditional masonry was built with historic mortar that remained softer and more flexible than the stone or brick around it. This flexibility allowed the joints to act as a buffer, absorbing movement and releasing moisture through evaporation. The wall could manage humidity, rainfall, and temperature shifts without forcing stress into the masonry itself.

Problems begin when incompatible mortar or non-breathable coatings block the wall’s ability to release moisture. Once moisture is locked inside, it expands during freeze-thaw cycles, pushes against the surrounding material, and accelerates long-term damage. Instead of the joints taking the intended stress, the stone or brick ends up bearing the burden.

Conclusion

Maintaining breathable walls supports the original science behind traditional masonry. When moisture moves freely, the wall can function as designed, maintaining its Character, durability, and appearance while reducing the likelihood of deterioration that eventually leads to reconstruction. Understanding breathability is one of the most important steps in caring for any long-standing masonry home.