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James Hardie Home Additions & ADU: The Orlando Owner’s Guide
If you’re planning a home addition or ADU in Orlando with James Hardie siding and trim, the installed cost typically lands between $45,000 and $130,000 for the addition itself, with ADU construction running $90,000 to $220,000 depending on size, site prep, and finishes. We stock and install James Hardie-compatible siding, trim, and weather barriers for additions across Orlando, and most owners call us when they realize their existing Hardie lap siding or trim boards are failing at the seams or wicking moisture into the framing behind the addition. You’ll usually spot it after a hard Orlando summer rain: paint peeling in vertical streaks, boards swelling at the butt joints, or trim that feels soft when you press on it.
Which James Hardie Models This Applies To
James Hardie makes three primary siding lines that show up on Orlando additions and ADUs: HardiePlank lap siding, HardiePanel vertical siding, and HardieTrim boards. HardiePlank comes in 4×8, 5.25, 6.25, 7.25, and 8.25-inch exposures, and the width matters when we’re matching an addition to existing siding on the main house. HardieTrim is sold in 4/4 and 5/4 thicknesses, and here’s the gotcha most Orlando homeowners don’t know: the 5/4 trim is what you need if you’re matching existing window and corner trim on a house built before roughly 2015, because James Hardie changed the standard trim thickness around then. If you buy 4/4 thinking it’s the same, the corners will sit proud of the siding plane and water will find the gap.
We always check the back of an existing board for the embossed James Hardie stamp and the product code. That code tells us the exact profile and color, and it’s the only reliable way to match a repair. We install genuine James Hardie products for additions and ADUs, not aftermarket generics, because the warranty registration on the rest of the structure often requires continuity of product from a single manufacturer. Mason Remodeling Co Orlando is an independent contractor and not affiliated with James Hardie, but we’ve been working with their product lines since our founding in 2004, and we also handle cabinetry from KraftMaid and surfaces from Cambria and Silestone on the interior side of the same addition.
Styles & brands we work with
Signs Your James Hardie Home Additions & ADU Is Failing
- Vertical paint streaks below butt joints. This is water running down behind the siding from a failed joint flashing or missing caulk. In Orlando’s afternoon downpours, that water sits against the sheathing for hours, and paint streaks are the first visible sign.
- Swelling or mushrooming at board ends. Hardie board is cement-based, but if the factory-cut edges were never primed before installation, they absorb water and swell just like wood. This is the single most common failure we find on additions built in the last 10 years.
- Soft or flaking HardieTrim at window and door perimeters. Trim boards collect water at every corner. Once the factory seal coat breaks down, usually around year 12 to 15 in Florida heat, the trim starts to delaminate and crumble at the edges.
- Gaps opening between boards in dry winter months. James Hardie expands and contracts with humidity. Orlando swings from near-100% humidity in September to dry air in January, and if the original installer nailed too close to board edges, you’ll see hairline gaps open and close seasonally.
- Brittle, cracked caulk lines at trim intersections. The caulk itself is a wear item in Orlando. UV exposure and thermal cycling crack it within 3 to 5 years regardless of brand. When it fails, water gets behind the siding and the real damage starts.
See the difference
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After
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After
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AfterReplacement Cost & What’s Included
A full home addition in Orlando with James Hardie siding runs $45,000 to $130,000 installed, and a detached ADU runs $90,000 to $220,000. Those ranges include site prep, foundation, framing, roofing, electrical, plumbing, insulation, drywall, and the Hardie siding and trim package. If you’re only replacing failed siding or trim on an existing addition, the siding portion alone typically runs $8 to $14 per square foot installed, including tear-off, water-resistive barrier, flashing, and all labor.
What drives the price: two-story work costs more than one, scaffolding on a zero-lot-line addition in College Park or Thornton Park adds time, and matching existing trim profiles on older Orlando homes can require custom ripping. Every project we quote gets a written price before work starts. That’s the Mason Remodeling standard, not an option, and it includes a written guarantee covering our workmanship for 365 days from the completion date. If anything we installed fails in that window, we return and fix it at no charge.
Call (850) 920-7745 for a free estimate. We’ll walk the existing siding with you, measure the boards, and give you a line-item written price.
DIY or Call Us?
Hanging a single piece of HardiePlank on a ground-level shed wall is a reasonable weekend project. Hanging it on a two-story addition, working from scaffolding, cutting cement board with a circular saw, and flashing it correctly so water stays out of your new ADU is a different animal. We’ve been called in to fix DIY Hardie jobs in Orlando where the boards looked fine from the street but the sheathing behind them was black with mold within two years.
The tools alone, a Hardie-specific saw blade, pneumatic nailer, proper flashing, and rolls of housewrap, will set you back several hundred dollars before you touch a board. And the work is heavy. A single 12-foot HardiePlank in the 8.25-inch exposure weighs about 30 pounds. On a ladder, that weight has a way of making decisions for you.
Most Orlando homeowners are better served having a trained crew handle Hardie installation, especially on additions and ADUs where the warranty on the entire structure depends on the siding being done right. If you want to check your own siding before calling us, feel a few trim boards after a rain. Soft spots mean water is already in the material. You won’t fix that with caulk.
Tell me what the problem is. We’ll figure out the rest from there. Call (850) 920-7745 to schedule a free estimate.
FAQs
James Hardie siding carries a 30-year limited, non-prorated warranty, and in Orlando’s climate we typically see 25 to 35 years of service life before boards need replacement, with trim failing first, usually at the 12 to 15 year mark due to UV and moisture exposure at corners. Call (850) 920-7745 if you want us to assess your existing siding and give you a straight answer on how much life it has left.
Yes, individual boards and trim pieces can be replaced without re-siding the whole addition, and that’s usually the right call when damage is isolated to one wall or a few trim boards around windows. If the failure is widespread, meaning water has reached the sheathing in multiple areas, a full re-side is often cheaper in the long run than chasing one repair after another. Call (850) 920-7745 and we’ll give you an honest recommendation.
For a single-story addition up to about 1,200 square feet of wall area, we typically complete the tear-off, barrier inspection, and new Hardie installation in 3 to 5 working days. Two-story additions and ADUs with complex trim packages run 5 to 8 working days, and we’ll put that schedule in writing as part of the estimate. Call (850) 920-7745 for a free estimate and a firm timeline.
We keep the most common James Hardie profiles in stock at our Orlando yard: 6.25-inch HardiePlank in the standard colors, 4/4 and 5/4 HardieTrim, and the flashing and barrier products we use on every job. Less common profiles and custom colors are ordered from our James Hardie distributor, typically a 3 to 5 day lead time in Orlando. Call (850) 920-7745 and we’ll check stock while you’re on the phone.
Written by Isaac Pruett, Owner, Mason Remodeling Co Orlando at Mason Remodeling Co Orlando, serving Orlando and nearby areas.
