James Hardie sells the same 8-1/4" HardiePlank in two versions. HZ5 is for climates with freezing winters and HZ10 is for the rest. The shed designer used to price HZ10 everywhere and mention HZ5 only in a note. It now has a Climate setting. "Freezing winters" switches every fiber cement plank to HZ5. The setting changes nothing else, so a T1-11 or LP shed costs the same either way.
What the plank costs, from search-result copies read on 2026-10-30:
| Plank, 8-1/4" x 12 ft | Home Depot | Lowe's |
|---|---|---|
| HZ10 (model 215572) | $12.48, or $10.61 each for 25+ | no listing found |
| HZ5 (model 6000265) | $17.98, or $15.28 each for 25+ (copy about 261 days old) | $14.98, or $12.73 each for 25+ (copy about 707 days old) |
The 10x10 lap-sided preset takes 58 planks. Switched to fiber cement, it costs $3,667.86 with HZ10 and $3,938.72 with HZ5, $270.86 more at Home Depot. Lowe's HZ5 price would close most of that gap, but its copy is nearly two years old. A person should check it at the store before relying on it.
5/4 trim. LP's install guide asks for its 540 Series (5/4) trim, so the lap butts don't stand proud of the corner boards. Until now the tool used only 3/4" primed pine 1x4, and its build step said as much. Wall trim now has a third choice: 5/4 corner boards and casings. With fiber cement the tool uses HardieTrim, and with engineered wood lap it uses LP 540.
| Trim, 5/4 x 3-1/2" | Price | Source |
|---|---|---|
| HardieTrim HZ10, 12 ft | $23.48 ($19.96 each for 25+) | Home Depot, model 216764 |
| HardieTrim HZ5, 12 ft | $21.25 | Lowe's, a copy about 707 days old |
| LP 540, 16 ft | $24.99 | Stine Home + Yard |
No copy of Home Depot's LP 540 page (model 41161) showed a price. Lowe's showed $24.98 for a 540 board, but the copy didn't give its size, so the tool doesn't use it.
On the 10x10:
- LP 540: six 16 ft boards cost $149.94, against $129.15 for pine. That's $20.79 more.
- HardieTrim: ten 12 ft boards cost $234.80, which is $105.65 more.
LP 540 comes only in 16 ft lengths. The tool buys it even when you've set a 12 ft haul limit, because there is no shorter board to buy.
Neither change touches the default design. Both are choices you make on the page, and the design-swap list now offers 5/4 trim on any lap-sided shed with pine trim. Every price links its source and can be edited. The tool is a planning aid, not an engineered or code-checked design.