This is actually a very common question and one I tend to answer with each home visit I make to consult those who are considering HardiePlank siding for their Tulsa home. When old siding is already in place, knowing how new siding is installed is highly important and obviously is going to determine just how successful a new install is in terms of longevity and proper installation.
The actual question is should the current siding be removed with OSB installed, or should the current siding remain to act as a substrate (an additional layer beneath the top layer) under the new HardiePlank siding. Something you will want to keep in mind when making this decision is how long HardiePlank will be on your home; more than 50 years. Do you need a substrate? It’s recommended, whether you choose new OSB or your current siding (if it’s in good shape and installed to the studs). Now you probably want to know just how you’re supposed to decide.

Keeping Your Existing Siding

Without properly inspecting and examining your current siding, it’s probably hard to tell its actual condition. That said, this is where you want to start when deciding if you should keep it. The James Hardie manual actually agrees that current siding works fine for a substrate but only if it’s in acceptable condition. What’s acceptable? Siding that is free of warps, bows, curls, and rotting or peeling of the laminate.
To understand the process more I will now explain what happens when I arrive at a Tulsa home whose homeowners are considering James Hardie siding installation. When we first meet I will ask several questions about the home. This is only to have a complete understanding of any past or present issues taking place with the siding. This includes any water leaks or penetration issues that have previously happened or very recently. In addition, many times the siding will come off regardless, just to check underneath and ensure there isn’t any preexisting damage or issues with the studs and wall cavity.
In addition to water leaks and/or damage, pest damage is also something I look for. Rodent nests and holes from raccoons, squirrels and even birds are what I look for. If none are found we can most likely use your current siding as the substrate. You can save money this way and it also shortens the time it takes to complete the project.

Using Oriented Strand Board (OSB)

If I find that the home has suffered from water or pest damage I will advise that it be removed. We can then continue inspecting the studs, wall cavity and any other areas to be sure of exactly what we’re covering up. Even if you don’t have damage and want to install new OSB, we can do that. Doing so also comes with its own benefits which includes the ability to inspect the wall and framing, insulation and overall integrity of the home’s structure. This is important before installing Hardie Plank siding, or any siding for that matter. I would like to take a moment and point out that the warranty accompanying James Hardie siding becomes void if the siding is installed incorrectly or not accordingly.
With that said, I always recommend that homeowners work with a professional siding contractor when it comes to upgrading their home. A specialist will have the information you need to make the best decision and also have suggestions on the best siding option for your home depending on the area you live in.
Please feel free to contact us if you have more questions regarding James Hardie siding installation.