Myths About Waterproofing Chimneys

No matter where you live, you cannot escape the wrath of Mother Nature. Whether you reside in the rainforests of western Washington, the sunny and hurricane-prone areas of Florida, or snowy New England, your masonry chimney is constantly battling the elements. In fact, water is your chimney’s worst nightmare. Without a professional waterproofing solution, years of continuous exposure to rain, snow, ice, and UV rays can cause your masonry chimney to deteriorate to the point of collapse. 

Dispelling Five Popular Myths About Waterproofing Chimneys

Contrary to some myths, your chimney requires waterproofing to shield it from the elements. Let’s dispel the myths:

1. Bricks shouldn’t be waterproofed so they can “breathe.”

Many off-the-shelf sealants trap moisture, but Raintite® is specifically formulated for masonry chimneys. This solution creates a vapor-permeable membrane that allows the masonry to breathe while effectively repelling rain, snow, ice, and UV exposure.

2. A lined chimney doesn’t need waterproofing.

A chimney liner protects the inside of your flue from heat and combustion byproducts, but the exterior masonry is still vulnerable. Rain and snow still soak into the brickwork, leading to cracking, crumbling, and spalling, and eventual structural collapse.

3. My chimney looks fine and doesn’t need waterproofing.

Brick and mortar are naturally porous materials, which means they absorb moisture. However, by the time you notice visible damage like mortar decay, cracked bricks, or mold, the water has likely been causing internal damage for years. Waterproofing is a preventive measure that can help extend your chimney’s lifespan.

4. I don’t have any leaks, so there is no need for it.

Waiting for a leak to appear means the water has already infiltrated the masonry, flashing, and crown, likely causing expensive damage to your drywall, attic, or roof deck. Professional waterproofing with Raintite® can help prevent costly chimney leaks.

5. I was told waterproofing isn’t necessary.

This advice is often from general contractors who aren’t certified chimney experts. Because chimneys are the most exposed part of your home—subject to extreme temperature swings and seasonal weather changes—they require specialized protection.

What is Raintite®

Raintite® is a professional-grade, “breathable” water repellent specifically formulated for vertical masonry surfaces. Unlike some sealants that simply cover the surface of the brickwork, Raintite® penetrates deeply into the pores of brick and mortar. It forms a molecular bond that alters the chemical structure, causing the masonry surface to repel moisture.

The Benefits of Raintite®

There are many valuable benefits to using Raintite®, including:

• Vapor Permeable: It allows the chimney to “breathe” and for trapped moisture to escape.
• Moisture Protection: Locking out moisture inhibits mortar decay and prevents masonry damage.
• Mold & Mildew Resistance: It helps maintain a healthy chimney and home.
• UV Protection: Unlike other water-resistant products, Raintite® won’t break down under intense sunlight, protecting against the damaging effects of UV exposure.
• Improves Appearance: Its moisture protection prevents efflorescence, an unsightly white powdery stain that appears across the brickwork.

How Long Does Waterproofing Last

While weather and maintenance are key factors, Raintite® typically provides robust protection for 5 to 10 years. However, the condition of your masonry and local climate conditions will influence longevity. Maintain your annual chimney inspections, and your certified sweep will let you know when reapplying Raintite® is necessary.

Waterproofing Chimneys with Raintite®

Raintite® is a specialty product exclusively for use by Approved Industries factory-authorized chimney and fireplace professionals for proper application and safety. This environmentally friendly solution is explicitly formulated for waterproofing chimneys. Its vapor-permeable membrane allows trapped moisture to evaporate while repelling rain, ice, and snow, and protecting against UV exposure. Contact an Approved Industries certified installer near you to learn more about waterproofing your chimney.