Common James Hardie Siding Problems and What Causes Them

Swelling or crumbling at the bottom edge

What you see: the lowest boards look puffy, soft or flaky, with paint peeling along the edge.

Cause: the edge has been sitting in moisture. Soil, mulch, a deck, a step or a snowbank is touching the siding, or a downspout is soaking it.

Fix: replace the damaged boards and restore the gap. See clearances.

Gaps opening at butt joints

What you see: visible gaps where two planks meet end to end.

Cause: joints not treated as the manufacturer specifies, boards not fastened into framing, or movement in the wall behind.

Fix: depends on the cause. It may be a matter of correct joint treatment and refastening.

Cracked boards

Cause: impact, nails driven too close to an edge or overdriven, boards carried flat and flexed during installation, or framing movement.

Fix: replace the board. See repairs.

Loose or rattling boards

Cause: fasteners that missed the studs, too few fasteners, or the wrong type.

Fix: refasten correctly. If it’s widespread, the whole wall needs checking.

Peeling or flaking paint

Cause: on site-painted boards, usually painting in poor weather, over a dirty or damp surface, or with unsuitable paint. Moisture getting into the board from behind or from an unsealed edge will also push paint off.

Fix: find the moisture source first, then prepare and repaint. See repainting.

Fading or patchy colour

Cause: sun exposure over time, more on south and west walls and on dark colours. Patchiness can also come from touch-up paint applied too broadly.

Fix: cleaning sometimes restores more than you’d expect. Otherwise repaint.

White powdery deposits

Cause: mineral salts carried to the surface by moisture, known as efflorescence. It can appear on cement-based products and often fades with weathering.

Fix: gentle washing. If it keeps returning in one place, look for a moisture source.

Water stains or damp inside the wall

Cause: not the siding itself. Missing or badly lapped flashing, a failed weather barrier, or a missing kick-out flashing where a roof meets a wall.

Fix: this needs proper investigation. See weather barrier and flashing.

Failed caulking

Cause: age. Sealant has a shorter life than the boards.

Fix: cut out and replace. Check it yearly.

Visible nail heads or waviness

Cause: face-nailing where blind nailing was expected, or an uneven wall behind the siding that wasn’t straightened first. Smooth textures show waviness more.

The pattern

Read back through that list. Product defects are rare. Installation shortcuts and neglected upkeep account for nearly everything. That’s why who installs the siding matters as much as what it is, and why two warranties exist: the manufacturer’s for the product and the installer’s for the work. See the warranty guide and questions to ask an installer.

Seeing one of these on your house? Ask for an inspection.