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Do You Need Plywood Behind Hardie Board Siding? Quick Guide

Hardie Board is excellent for it’s durability and long-life span. Especially when used as a siding. But, many still argue over if you should install a layer of plywood beforehand.

Do You Need Plywood Behind Hardie Board?

Well, we have done some research and can finally settle the debate! While installing a layer of plywood behind a Hardie board does offer more security. But it is not always necessary. 

In this article, we talk about if you should install plywood before Hardie board siding. Or go straight for it! We also cover the most common mistakes made when installing Hardie board.

Jamie Hardie Board siding is a popular option for many projects. This means you and other installers need to know how to do it without causing a mess.

We can say that it is not necessary to install plywood behind a Hardie board. But it does add some benefits that make it worthwhile. 

Why Use Hardie Board Siding?

James Hardie siding is often selected due to its sleek appearance and its ability to remain in top condition for over 30 years. Even if you live in an area with extreme weather conditions. 

No matter where you live, Hardie boarding needs the correct treatment and storage to last. This means following the instructions to the letter.  

James Hardie siding is popular for being durable in harsh environments and pests. It is extremely low maintenance and comes with an excellent 15-year warranty. 

These benefits make it worthwhile to have your home looking and feeling amazing. 

To put it bluntly, if you want your home to last and look brilliant, you use Hardie board siding. 

Is Plywood Necessary With Hardie Board?

James Hardie is a range of fiber cement products on offer that are useful for a wide range of projects. However, when it comes to siding, the best option is Hardie Plank.

The product uses fiber cement and James Hardies ColourPlus technology. This makes it extremely long-lasting and requires minimal touch-ups. 

As you begin installing Hardie Plank, you begin to think that you need an extra layer. Or should you install it alone.  In more cases than not, you do not need to install plywood behind Hardie board siding. 

Hardie Plank is easy to install on top of existing subfloor and sheathing. Meaning there is no need for another layer.

Yet, it is still common practice for people to install plywood behind Hardie Plank. This adds a layer of protection to the home. 

Not installing plywood behind Hardie Plank will result in the need for let-in bracing. This ensure the walls are strong and stable. Many use a layer of Tyvek or tar paper underneath Hardie Plank instead of plywood. 

Advantages of Using Plywood Behind Hardie Plank 

While it is not necessary to add a layer of plywood behind Hardie Plank, there are an array of benefits to doing so: 

  • Extra Insulation: Plywood will act as an added layer of insulation to the home. This keeps the heat inside the home which will lower your energy bills in the winter.
  • Pest-resistant:  Adding a layer of plywood behind Hardie Plant offers more protection. Even though the product is pest-resistant on its own.
  • Quieter: When installing plywood behind Hardie Plank, you will hear less of the world.
Do You Need Plywood Behind Hardie Board?

Common Mistakes When Installing Hardie Board 

While Hardie Plank is extremely durable, there are still mistakes that you can make. From storage to touch-ups, there is plenty that can go wrong. 

We have 3 of the most common mistakes that happen when using Hardie Plank to help you avoid them. 

1. Storage 

Many fall victim to storing their Hardie Plant products wrong. Even with the instructions on the packaging. The storage requirements are as follows:

  • Store Hardie Plank on a pallet to keep it away from ground moisture. Keep the pallet at ground level without having the product touch the ground or risk ruining the siding. 
  • Store Hardie Plank indoors or in a waterproof setting. The packaging that the Hardie board comes in is not waterproof meaning the product needs extra protection in storage. 

You must ensure your contractor only installs Hardie siding when it is dry. Otherwise, it will show signs of damage and staining. Throwing your money down the drain. 

2. Bad Caulking 

When installing your Hardie Plank and it is near a trim board, you should leave an 1/8 inch gap. This leaves room for the caulking to enter and seal the edges.

When purchasing siding from James Hardie, it also comes with high-quality caulking. This caulking matches the color of the siding for a seamless look. 

Select the caulking that matches the color of the siding for the best result. Ensure that your contractor or siding installer knows to only apply a small amount of caulking for a sleek, clean finish. 

3. Bad Touch Ups

The most frequent blunder made by James Hardie installers is by far touch-up mistakes. The sheen of the touch-up James Hardie sends out isn’t quite the same because it paints and cures its siding in its plants. 

Therefore, when painting nails or minor flaws in the siding and trim, contractors must take care to use the proper quantity of paint.

Final Thoughts 

James Hardie siding has quickly become a popular option for exterior siding on homes across the world. From the UK to Canada, it is popular for its long-lasting finish and ability to last for over 30 years. 

While there is no need to install plywood behind Hardie Plank, it does come with some great benefits that can make it worth the extra step. 

Above you will find everything you need to know about installing plywood with Hardie board siding. You will know how to avoid the common mistakes people make!

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