The charm of classic wood siding is undeniable, but if your home’s exterior is showing signs of wear and tear, you might be considering an upgrade. Hardie board, known for its durability and modern appeal, is an enticing option. However, before you dive into this home improvement project, it’s crucial to understand the ins and outs of installing Hardie board over existing wood siding.

So, Can You Install Hardie Board Over Wood Siding?

The short answer is that it will depend on the type of wood siding you have. The installation process varies significantly based on whether your home has cedar shingles, cedar lap siding, or a flat wood panel system.

Cedar Shingles or Cedar Lap Siding

If your home features cedar shingles or cedar lap siding, installing Hardie board directly over them is not advisable. Why? Because Hardie board requires a smooth, flat surface to adhere properly, and cedar shingles or lap siding create an uneven surface that can lead to significant issues down the line. This kind of installation would not only void any warranty from James Hardie but could also result in a wavy appearance and improper attachment, leading to moisture problems and structural concerns. In such cases, it’s essential to remove the existing wood siding before installing the Hardie board.

Flat Wood Panel System

For homes with a flat wood panel system, the process is a bit different. Here, we typically remove all the trim boards, address any wood rot, and ensure the surface is flat and secure. We then mark the stud lines and install the Hardie board directly onto the wood panels. This method is the most common and effective, especially in areas like Johnson County, where about 95% of homes can use this installation method.

The Importance of Addressing Wood Rot

One of the most critical steps in the process is dealing with any wood rot. Installing a Hardie board over rotted wood is a recipe for disaster. Not only does it compromise the structural integrity of your home, but it also traps moisture, leading to further damage over time. Before we install Hardie board, we thoroughly inspect the wood panels and replace any rotted sections to ensure a solid, long-lasting installation.

Handling Severe Wood Rot

In some rare cases, the wood rot may be so extensive that we have to remove entire sections of the wall. While this is something we try to avoid due to the potential for interior damage (such as nail pops in the drywall), it’s sometimes necessary to ensure a stable, secure installation. This step is only taken in extreme cases—less than 5% of the time—but it’s an essential part of our commitment to doing the job right.

Common Mistakes to Avoid

Installing Hardie board over wood siding is not without its pitfalls, especially if the job is done incorrectly. Here are some common mistakes that can lead to serious problems:

1. Installing Over Cedar Shingles or Lap Siding: As mentioned earlier, this is a big no-no. It creates an uneven surface that can cause waves, moisture pockets, and improper attachment to the studs.
2. Using Vinyl Siding Over Cedar: Another mistake we often see is contractors using vinyl siding over existing cedar shingles or lap siding. While this might seem like a cost-effective solution, it often leads to even more problems down the road, such as poor aesthetics, structural issues, and moisture damage.
3. Covering Up Wood Rot: Never install any siding over rotted wood. It’s like putting a bandage on a broken bone—sure, it might cover up the problem temporarily, but it’s not fixing the underlying issue. Always address and repair any wood rot before installing new siding.

Questions to Ask Your Contractor

Before hiring a contractor to install a Hardie board over your wood siding, it’s essential to ask the right questions. Here are a few key points to discuss:

• How do you handle wood rot? Ensure the contractor has a clear process for identifying and repairing wood rot before installation.
• What’s the process for removing old siding? If your home has cedar shingles or lap siding, make sure the contractor plans to remove it rather than install over it.
• How do you ensure proper attachment to the studs? Properly attaching the Hardie board to the studs is crucial for a secure, long-lasting installation.

In Summary

Installing Hardie board over wood siding can be a great way to update your home’s exterior, but it’s crucial to do it right. Whether you have flat wood panels or cedar shingles, understanding the proper installation process and avoiding common mistakes is key to ensuring a successful outcome.

If you’re considering this type of installation, we’re here to help. Contact us today to learn more about how we can give your home the beautiful, durable exterior it deserves.