Hardie board, a widely used cement board siding option, is known for its durability and weather resistance. While it isn’t entirely waterproof, it’s highly water resistant. In this article, we’ll explore the properties of Hardie board, its water resistance capabilities, and how to effectively protect it from moisture damage.
Hardie Board’s Water Resistance
Hardie board is a combination of cement, sand, and cellulose fibers. This construction gives it excellent water resistance, making it a favored choice for exterior and interior use in humid environments.
Is Hardie Board Waterproof?
Hardie board isn’t technically waterproof. It does have significant water resistance and can absorb and release moisture, allowing it to withstand exposure to rain and snow while maintaining its structural integrity.
Water-resistant materials can resist water penetration to a certain degree but aren’t completely immune to moisture. Waterproof materials are intended to be impervious to water, no matter the length of exposure. Hardie board is water resistant, retaining strength and appearance under wet conditions.
Hardie Board Uses
You can use Hardie board for a range of purposes in and around your home:
- Exterior siding: Its resilience against weather makes it ideal for exterior siding, shielding homes from moisture while enhancing appearance.
- Bathroom and shower walls: Hardie board’s water resistance makes it a reliable choice for bathrooms and shower walls frequently exposed to moisture.
- Kitchen backsplashes: You can use Hardie board for kitchen backsplashes, providing a surface that withstands spills and steam.
- Outdoor kitchens: Hardie board’s moisture resistance makes it well suited to outdoor kitchens.
- Basement finishing: Hardie board is a robust option for basements, where moisture can be a concern. It helps prevent water damage and adds an extra layer of protection.
Should You Waterproof Your Hardie Board?
Hardie board is naturally water resistant, but you might choose to incorporate additional waterproofing measures in specific scenarios.
Consider waterproofing Hardie board for these uses:
- Shower enclosures or other areas with direct water contact
- Exterior walls in regions with heavy rainfall or high humidity
- Basements or areas prone to water seepage
Benefits of Waterproofing Hardie Board
A waterproof barrier provides better protection against water penetration, enhancing Hardie board’s ability to repel moisture. A robust waterproof layer extends the lifespan of your Hardie board, saving you money in the long run. It also minimizes the risk of water damage to your home.
How To Waterproof Hardie Board
The following step-by-step guide takes you through the Hardie board waterproofing process:
1. Seal Gaps
Thoroughly clean the surface to eliminate dirt or debris, then seal any gaps and joints in the Hardie board before waterproofing with a premium silicone sealant. Work carefully and allow adequate drying time before advancing to the next step.
2. Apply Liquid Membrane
A liquid waterproofing membrane creates a seamless protective barrier over the Hardie board surface, fortifying its defense against moisture. Select an appropriate liquid membrane product that works with Hardie board. Use a brush or roller to apply the first coat thoroughly and evenly across the surface. While this initial coat is still wet, embed membrane fabric into corners and seams to enhance durability.
Apply a second coat of liquid membrane over the fabric and entire surface area. Follow the manufacturer’s directions for proper drying time.
3. Repeat the Process
Add a third coat of liquid membrane once the second is dry for maximum protection, especially in areas with high moisture levels. Make sure you cover the entire area, especially corners and seams. Allow ample time for the final coat to cure fully before tiling or finishing the surface.
Can You Tile Directly on Hardie Board?
One advantage of using Hardie board and other cement boards is that they work as a substrate for tile installation. Cement board is a stable, moisture-resistant foundation for tile—good for bathrooms, kitchens, and other moisture-prone areas.
Benefits of Tiling on Cement Board
The benefits of tiling on cement board include:
- Stability: Cement board resists warping and expansion when exposed to moisture, making it a sturdy base for tile.
- Durability: The combination of cement board and tile creates a long-lasting, water-resistant surface.
- Mold resistance: Cement board resists mold growth, fostering a healthier environment.
Proper Installation for Tiling
Follow these steps to lay tile over Hardie board:
- Double-check that the board is installed properly and securely attached to the subfloor or wall studs for stability.
- Tape and mud the seams between boards to create an even, uniform surface.
- Apply a layer of thinset mortar.
- Use the appropriate tile adhesive and grout for your chosen tiles. This helps secure the tiles firmly and enhances moisture resistance.
Maintaining Hardie Board’s Water Resistance
Although Hardie board is naturally water resistant, proper maintenance preserves its protective properties over time.
Regularly clean dirt and debris that may trap moisture against the surface to preserve its water-repellent properties. Promptly address any damage or gaps to prevent water infiltration. Touch up paint as needed to help maintain the moisture barrier.
