Buying a Home with Hardiplank Siding? 3 Installation Red Flags to Look For
Are you considering buying a house with Hardiplank siding? It's one of the most popular exteriors in Montgomery County, and for good reason. It's durable, fire-resistant and holds paint well. But it only performs as well as it was installed.
Today I walked a home with a buyer, and the siding told a story. We found vertical cracks in numerous boards. There were open gaps where boards should have been butted tightly together. And in other sections, boards were jammed in with no gap at all where the manufacturer requires one.
None of this is obvious from the curb. Here's what we saw, why it matters, and what to look for on your own home tour.
What Hardiplank is, and why installation matters
Hardiplank is James Hardie's brand of fiber cement lap siding. It's made from cement, sand and cellulose fibers, so it doesn't rot, warp or attract termites the way wood can.
Fiber cement is rigid, though, and it has to be installed exactly as the manufacturer specifies. James Hardie's installation instructions set requirements for nailing, joints and clearances. Their instructions also warn that not following them may affect warranty coverage.
When those details are skipped, water finds its way behind the siding. That can mean damaged sheathing, rot in the framing, mold and expensive repairs that a buyer inherits.
Red flag #1: Vertical cracks in the boards
A crack running up and down a board is a warning sign. Common causes include nails placed too close to the end of a board, nails driven too hard, and boards forced into place with no room to move.
A cracked board is more than cosmetic. Each crack is an opening for water, and it can keep growing with each freeze-thaw cycle.
What to look for: Walk the whole exterior, not just the front. Pay extra attention near board ends, around windows and doors, and on the sunniest and most exposed sides of the house.
Red flag #2: Gaps at butt joints
A butt joint is where two boards meet end to end in the same row. James Hardie calls for these ends to be installed in moderate contact, meaning snug against each other, with joint flashing recommended behind the seam.
Caulk is not the fix here. The manufacturer does not recommend caulking these field butt joints, so a visible gap stuffed with caulk is still a red flag.
What to look for: Scan each row of siding for seams. You should see two board ends touching. A visible strip of shadow, or of the wrap behind the siding, means water has a path in.
Red flag #3: No gaps where gaps belong
This one surprises people. Butt joints should be tight, but other spots need a deliberate gap so the siding can move and stay out of water. Here are the typical clearances from James Hardie's instructions:
Siding meeting window, door and corner trim: about 1/8", then caulked. This lets the joint be sealed and allows for movement.
Bottom of siding above the ground: 6" minimum. This keeps boards from wicking up moisture from soil and mulch.
Siding above a roof (like a garage or porch roof meeting a wall): 1" to 2", depending on the instruction version. This keeps boards out of water running down the roof.
Siding above decks, patios and paths: at least 1" to 2". This keeps boards away from splash and standing water.
Requirements vary by product and instruction version, so your inspector or a siding contractor should confirm what applies to the home you're buying.
What to look for: Boards touching the roof shingles, buried in mulch or soil, or jammed against trim with no caulked seam.
What to do if you spot these issues
Take photos. Note where on the house each problem is so your inspector can look closely.
Get a thorough home inspection. Ask your inspector to pay specific attention to the siding, especially joints, edges and clearances.
Bring in a specialist if needed. A siding contractor can tell you whether the issues are isolated or widespread, and what a repair would cost.
Ask about the siding's history. Find out when it was installed, by whom, and whether any warranty or paperwork is available.
Use what you learn. Depending on your contract, findings can support a repair request, a credit, a price adjustment or a decision to walk away.
A few other things are worth a glance while you're outside: peeling paint, nail heads that are rusted or sunk into the board, soft or swollen spots, and missing kickout flashing where a roof edge meets a wall.
The bottom line
Hardiplank is a great siding choice when it's done right. The problems we found today weren't about the product. They were about how it was installed. Knowing what to look for helps you ask the right questions before you're committed.
If you're buying in Bethesda, Potomac, Darnestown or anywhere in Montgomery County, I'd love to help you look past the staging and see the whole house. Reach out anytime with questions about a home you're considering.
Kris Paolini, Principal Agent, Redfin | The Founders Group | @sold.by.kris
Sources: James Hardie HardiePlank installation instructions; InspectAPedia fiber cement gap specifications