Unlike wood or drywall sub-surfaces, cement backer board will not rot, warp or grow mold and mildew when exposed to water.
Exterior cement board is easy to install and provides enhanced durability. Additionally, cement board exterior walls are better able to keep moisture out of buildings, helping to prevent mold, mildew, and other common forms of water damage.
Durock® Brand Cement Board offers high mold resistance with no mold development according to the ASTM G21 test. According to ASTM D3273, Durock® Brand Cementitious Board receives a perfect score of 10 out of 10 for resistance to the spread of mold and mildew under favorable fungi growth circumstances.
In independent tests, HardieBacker cement board achieves a 0 on the ASTM G21 (best possible score for mold resistance) and a 10 on the ASTM D3273 (best possible score against mold growth). The product is recognized as a non-combustible building material in ESR-2280.
the answer is yes up to three months. now if you know this is going to happen we highly recommend that you prime the board first to protect. them then when you are ready to fit onto the boards whether it be render paint or tiles. you must make sure the board is completely dry before you proceed.
If you're considering fiber cement siding, you want to know whether it is susceptible to rot. Put simply — no. This type of siding is made from four simple ingredients: cement, wood pulp, water and a type of filler. None of these materials is affected by rot.
Cement board will not fall apart when exposed to water. But like a concrete walkway, it can soak up water. It can also dry out and be perfectly fine.
Although the Hardie board isn't technically waterproof, it's resistant to water damage. It can get wet since it absorbs moisture efficiently, but it has exceptional drying capabilities and will not deteriorate when exposed to water.
Hardie siding does a great job of wicking moisture when it is installed on the wall, but when it's uncovered and flat on the ground it will absorb water. If your contractor installs Hardie siding when it's saturated, it may show signs of shrinkage or even staining over time.
The conclusion is that cement board is the only product you should be using when there is any chance of contact with water. Many times it's what you don't see behind the walls that has the biggest impact for longevity of your project.
Vinegar Solution
Spraying a vinegar solution (1 cup of vinegar per gallon of water) onto the surface, saturating it fully, should kill most strains of mold. Vinegar spray can be followed by power washing or manual hand scrubbing to remove the dead mold.
Mix one cup of bleach to 1 gallon of water. It can then be sprayed onto the concrete and scrubbed. Most of the mold should be removed through this method. A less aggressive method is to mix 1 cup of vinegar with 2/3 cups of water in a spray bottle.
For this reason, most manufacturers of fiber cement siding feel pretty confident in offering warranties of 30 years or more on the structure of the boards. That means that the boards themselves are guaranteed to last for at least 30 years when installed and maintained properly.
For most interior applications, Durock® Brand Cement Board Panels are not affected by water and do not need to be waterproofed. Durock® is water durable but not waterproof. If you're looking for added protection to water sensitive material behind the Durock®, you may consider adding a waterproofing membrane.
In general, cement boards are a highly moisture-resistant building material that can withstand the damp conditions found in bathrooms and showers, where water can accumulate and seep into the walls over time.
Hardie siding products resist moisture, mold, and mildew.
Dirt and filth from bird droppings, dust, and pollen can accumulate on the siding's exterior surface, diminishing the look of your house. James Hardie siding doesn't need to be cleaned very often. It is resistant to mold, mildew, and fading but can get dirty over time. Luckily, it's extremely easy to clean.
Is a vapor barrier required? Yes, HardieBacker 1/4'' cement board may be used in a shower. However, we recommend HardieBacker 500 if you need to make a smooth transition to drywall. The board must be mechanically fastened every 8'' on center to the wood or metal studs spaced a maximum of 16'' on center.
James Hardie® siding also is moisture resistant, so it will not rot like wood siding and fiberboard siding can.
If the area behind the backerboard must be kept dry, use RedGard® Waterproofing and Crack Prevention Membrane or Custom® 9240 Waterproofing and Anti-Fracture Membrane. Durock (USG): If waterproofing is desired, use USG Durock™ Tile Membrane or USG Durock™ Brand Waterproofing Membrane.
Most brands of concrete backer-board consist of a fibrous reinforcement cement composition molded into sheets. It is extremely hard and waterproof, meaning it will not deteriorate over time when exposed to water, making it ideal for use in high-traffic areas that are susceptible to the adverse effects of moisture.
Unless specifically manufactured as a waterproof product, cement board is water resistant but not waterproof. You must coat it with a fluid-applied waterproofing or apply a water-resistant barrier behind it that drains (BSC 2009b).
Unlike wood or drywall sub-surfaces, cement backer board will not rot, warp or grow mold and mildew when exposed to water. That's the main reason they're a go-to choice for permanent installations like this.