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What's behind your siding matters more than the siding

By Red Sky Exteriors · 5 min read

Siding is the raincoat. The water barrier and flashing behind it are the waterproofing. Get those wrong, and even the best siding will leak.

The water barrier does the real work

James Hardie's own Florida installation instructions say a water-resistive barrier is required, installed with flashing at penetrations and junctions per local code, and that Hardie "will assume no responsibility for water infiltration" (HardiePlank Florida Product Approval). In other words, keeping water out of your walls is on the installer.

Ask: "Are you replacing the house wrap, or going over what's there?"

Flashing at every opening

Windows, doors, and every spot where a roof meets a wall need flashing. That includes kick-out flashing, which sends roof water away from the wall instead of down behind the siding. Old flashing behind new siding is where leaks come from, and it's easy to blame the window or the roof later.

Ask: "Is new flashing included at the windows, doors, and roof lines?"

Installed to the manufacturer's instructions

Hardie's instructions cover fasteners, nailing, gaps, and clearances, like keeping the bottom of the siding off the ground (HardiePlank Florida Product Approval). Hardie's warranty also depends on proper installation. Hardie siding carries a 30-year non-prorated limited warranty, and ColorPlus finishes carry a 15-year finish warranty (James Hardie).

Ask: "Will this be installed to Hardie's instructions so my warranty stays valid?"

Rotted wood, priced up front

Once the old siding comes off, there may be soft sheathing underneath. You should see photos before anything is replaced, and your proposal should spell out how it's priced.

This article is general information, not engineering or legal advice. Code requirements can vary by jurisdiction.