Why Chimney Masonry Absorbs Water

Brick and mortar are exposed to wind-driven rain, snow and changing temperatures throughout the year. As mortar joints age or brick surfaces deteriorate, the chimney can become more vulnerable to moisture. Water entering small cracks or porous masonry may contribute to staining, spalling and progressive deterioration, particularly during repeated New Hampshire freeze-thaw cycles.

Repair Before Applying Masonry Water Protection

Waterproofing should not be used to hide damaged masonry. Open joints, loose brick, failed crown areas and visible cracks should be evaluated first. Repointing, brick replacement or crown repair may be needed so an appropriate masonry treatment is applied to a sounder surface rather than over unresolved defects.

Breathable Masonry Water-Repellent Treatments

Where suitable for the existing masonry, a breathable water-repellent treatment can help reduce absorption of wind-driven moisture while allowing water vapor within the masonry to escape. Product selection and application should match the brick, mortar and condition of the chimney rather than relying on a one-size-fits-all coating.

Waterproofing as Part of Complete Chimney Maintenance

Long-term moisture protection also depends on the crown, cap, flashing and mortar joints. Stone Master evaluates these related components so waterproofing can be coordinated with repairs where necessary. This helps address both water absorption through masonry and other common entry points around the chimney.

Chimney Waterproofing FAQs

Will chimney waterproofing stop every leak?

No. A chimney can leak through flashing, crown cracks, caps, open mortar joints or damaged brick. Waterproofing is one part of moisture protection and should be matched to the actual source of the problem.

Should deteriorated mortar be repaired first?

Yes. Failed joints and other masonry defects should be evaluated and repaired as appropriate before a water-repellent treatment is used.

Why is freeze-thaw weather hard on chimneys?

Moisture retained within vulnerable masonry can freeze and expand. Repeated cycles can contribute to cracking, mortar deterioration and brick spalling, which is why controlling water entry is particularly important in New Hampshire.