Chimney Waterproofing

Help Reduce Water Absorption Through Masonry

Professional chimney waterproofing applies a breathable masonry water repellent to suitable exterior masonry to help reduce water absorption while still allowing moisture vapor within the masonry to escape.

When Waterproofing May Be Appropriate

• The masonry is in serviceable condition but receives heavy weather exposure.
• Tuckpointing or masonry repairs have been completed and the chimney is ready for added protection.
• The chimney shows signs of moisture absorption without requiring major reconstruction.
• The homeowner wants additional protection for exposed masonry.

Repairs Should Be Completed First

Water repellent is not a substitute for repairing failed mortar, loose bricks, major cracks or a deteriorated crown. Those defects should be corrected before waterproofing so the treatment is applied to masonry that is in suitable condition.

Schedule Chimney Waterproofing

If your chimney masonry is in good repair and you want to help reduce future water absorption, AirPlease Missouri Chimney Services can evaluate whether waterproofing is appropriate.

How Water Damages Masonry

Moisture can enter pores, joints and small cracks. During freezing weather, absorbed water can expand and contribute to spalling and mortar deterioration over repeated cycles.

Breathable Water Repellent

Professional masonry water repellent is intended to reduce liquid water absorption while still allowing moisture vapor within the masonry to escape. It is different from simply painting the chimney with an impermeable coating.

Why Breathability Matters

Masonry can contain moisture from weather, indoor conditions, and normal vapor movement. A breathable treatment is intended to reduce liquid-water absorption without trapping normal vapor inside the wall assembly.

Waterproofing Application

The exterior masonry is evaluated first. Necessary repairs are identified before treatment, and the surface is prepared as required. The approved masonry areas are then treated with a breathable water-repellent product intended for exterior masonry.

Preparation Before Treatment

The chimney is evaluated first so failed joints, loose brick, crown defects and other necessary repairs are not hidden beneath a treatment. Recently repaired masonry may also need appropriate curing time.

What Waterproofing Cannot Do

Water repellent can help reduce absorption through treated masonry, but it cannot guarantee that every interior leak will stop. Roofing, flashing, siding and concealed construction can also be sources of water intrusion.

Water Repellent Is Not a Structural Repair

A masonry treatment cannot rebuild missing mortar, stabilize loose brick, or repair a failed crown. Those defects should be corrected first so the water-repellent treatment is applied to a serviceable surface.

Other Sources of Chimney-Area Leaks

Water visible near a chimney can come from crown defects, masonry absorption, flashing, roofing, siding, chase components, or concealed transitions. Treating the brick is only one possible part of a water-intrusion solution.

Frequently Asked Questions

Protect Repaired Masonry From Excessive Water Absorption

Water-repellent treatment is most useful after the masonry itself is in serviceable condition. It can help reduce rain absorption through treated masonry, but it does not replace crown repair, repointing, brick replacement, flashing work, or investigation of other leak sources. A good moisture-control plan starts by identifying where the chimney is actually vulnerable.