Installing Hardiplank Siding Over Existing Siding

Vinyl siding must be installed against a flat surface.

Installing hardiplank siding over existing siding.

Install hardiplank siding with joints butted in moderate contact. Why siding over existing siding is a bad move. Even though most reputable contractors will never install siding over existing siding there are knuckleheads out there that will say you can do it and it s not a problem. Several contractors have suggested that the wood siding need not be removed.

Optionally install the lap siding with a maximum 1 8 gap and caulk the joint see detail at right. Existing wood siding must be in good shape with no rot or mold and fastened tightly to the wall. This would be on an older house but the wood siding is in good condition. The first course of any wall should be installed over a 1 4 lath strip to ensure a consistent plank angle see figure 1.

Does this mean that hardieplank cannot be installed directly over existing wood siding without voiding the warranty. Installing vinyl siding over wood siding wood must be sound. Using existing siding for replacing siding the best place to start is to closely examine the existing siding to get a good understanding of what condition it is actually in. Thank you for any information.

Now you probably want to know just how you re supposed to decide. The best way to get the performance you expect from your james hardie products is to work with a professional contractor. Without properly inspecting and examining your current siding it s probably hard to tell its actual condition. It s recommended whether you choose new osb or your current siding if it s in good shape and installed to the studs.

Find a local contractor. The hardie website is unclear on this issue. James hardie siding is made of cement so it will absorb moisture if it is installed like this. According to the best practices manual from james hardie existing siding can be used as a substrate as long as it is in good condition meaning that it is not warped bowed curling delaminated or rotting.