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Owens Corning Home Additions & ADU: The Miami Owner’s Guide
Owens Corning home additions and ADUs in Miami typically run $53,100 to $153,400 depending on square footage, foundation work, and whether you’re adding to the existing structure or building a detached unit. We stock and install Owens Corning insulation, roofing, and structural sheathing products on every addition we build, and we can match existing Owens Corning materials on your current home so the new work doesn’t look like an afterthought.
Most Miami homeowners call us after they’ve already tried to make an older addition work and discovered the hard way that Florida heat, humidity, and hurricane code have different ideas. The walls sweat, the roof decking is soft, or the insulation from some decade-old install has compacted to the point where the room never cools below 82 in August. That’s when the project stops being a cosmetic upgrade and starts being a structural one.
Key Takeaways:
- Typical installed cost in Miami: $53,100 – $153,400
- We spec Owens Corning products to match existing materials on your home
- Written price before any work starts, every time
- 365-Day Done Right Promise on the completed addition
Which Owens Corning Models This Applies To
We work across the Owens Corning product lines most often used in Florida residential construction: the Duration series shingles, FOAMULAR rigid foam sheathing, EcoTouch insulation batts and rolls, and the ProPink blown-in system. For additions and ADUs specifically, the relevant compatibility question is almost always about the roof and wall assembly you already have, not a single part number.
Here’s the gotcha most people don’t know until they’re mid-project: an ADU built under Miami-Dade county code carries different wind-load requirements than a main dwelling, which means the sheathing thickness and fastening schedule on your existing home may not pass inspection for the new structure if you try to copy it. We spec Owens Corning FOAMULAR at the required R-value and thickness for the new build, not a copy of what’s on the old one. The same goes for roof decking: what held up on a 1998 addition won’t automatically meet current high-velocity hurricane zone standards.
If you’re matching an existing Owens Corning shingle color, pull a bundle label from the attic or garage. The shingle name, color code, and manufacturing plant code are printed on the wrapper. If you don’t have the wrapper, we can take a sample to our supplier and match it by sight. Duration shingles in common Florida colors like Driftwood, Estate Gray, and Brownwood are stocked locally, so matching isn’t a guessing game.
We’re an independent contractor, not affiliated with Owens Corning. We use their products because they perform in Miami’s climate, but the warranty on our workmanship comes from us.
Styles & brands we work with
Signs Your Owens Corning Home Addition or ADU Is Failing
- The room never cools below 80 in summer. This almost always means the wall or ceiling insulation has settled, gotten wet, or was never installed to begin with. Owens Corning fiberglass batts lose R-value permanently once they’re compressed or soaked. We open one wall cavity and know within ten minutes what the rest of the room looks like.
- You can feel heat radiating through the ceiling at night. In Miami, attic temperatures hit 140°F in July. If the roof decking isn’t properly vented or the insulation is too thin, that heat pours into the living space for hours after sunset. This is the most common complaint we hear from ADU owners.
- The drywall is showing water stains or soft spots near the roofline. That’s a flashing failure or failed underlayment under the Owens Corning shingles. By the time you see the stain, the decking underneath is usually already compromised. In Florida’s wet season, this goes from cosmetic to structural within months.
- Your utility bill climbs every summer even though your usage habits haven’t changed. Insulation failure doesn’t announce itself loudly. It just makes your AC work harder every year. Older fiberglass batts in South Florida lose effectiveness after 15 to 20 years due to humidity ingress, even when they look fine from the attic hatch.
- The walls feel warm to the touch on the west-facing side of the addition. That’s radiant heat gain through an under-insulated wall assembly. We see it constantly on additions built in the 1980s and 1990s, when Florida code gave a lot more latitude to builders wanting to cut costs.
See the difference
Before
After
Before
After
Before
AfterReplacement Cost & What’s Included
In Miami, a full home addition runs $53,100 to $153,400. A detached ADU starts at $106,200 and goes to $259,600. Garage conversions fall between $35,400 and $94,400. The spread comes down to four things: whether you’re building on a slab or need deep footings for a second story, how much of the existing roofline has to be rebuilt, what Owens Corning materials need to be matched, and whether the project triggers a full impact-window or door upgrade under current code.
Every quote we give includes the full scope: demolition if needed, framing, Owens Corning insulation and sheathing, roofing, rough electrical and plumbing coordination, drywall, trim, paint, and the final inspection. Nothing gets left out of the written price. If the permit office requires something extra when we pull the drawings, we handle it and you still know the number before we start.
Our workmanship on additions and ADUs is covered by the 365-Day Done Right Promise: if anything isn’t right within a year of completion, we make it right at no cost to you. That’s 365 days from the completion date, stated plainly.
| Project Type | Miami Price Range |
|---|---|
| Home Addition (attached) | $53,100 – $153,400 |
| ADU Construction (detached) | $106,200 – $259,600 |
| Garage Conversion | $35,400 – $94,400 |
| Roof Replacement (if tied into addition) | $9,440 – $23,600 |
DIY or Call Us?
You can safely check a few things yourself: look for visible water stains on ceilings and walls, check whether the addition feels warmer than the rest of the house, and pull an insulation sample from the attic if you have one. If the fiberglass is damp, moldy, or compressed to half its original thickness, you already know the answer.
What you shouldn’t do is open walls, pull shingles, or disturb old insulation without a plan. If the addition was built before 1990, there’s a real chance of asbestos in the drywall mud or older insulation types. And when it comes to roof work or structural changes on a home addition in Miami-Dade, permits and inspections aren’t optional. We pull them, we pass them, and you get documentation at the end. Call (850) 780-8123 if you suspect your addition has a problem you can’t see from the surface.
FAQs
Fiberglass insulation lasts 15 to 20 years in South Florida conditions before humidity and settle reduce its R-value enough to matter. Rigid foam sheathing like FOAMULAR lasts the life of the structure. If your addition is older than 20 years, call (850) 780-8123 and we’ll evaluate what’s actually in the walls.
Yes, if the framing is sound. We do insulation replacement, drywall repair, roof-over work, and resealing without tearing down a structure that doesn’t need it. If the framing or foundation has failed, replacement is the responsible path. A free estimate tells you which one you’re facing.
A detached ADU typically takes 5 to 8 months from permit approval to final inspection, depending on size and site access. Attached additions run 3 to 6 months. Miami-Dade permitting adds time to every project, so we file the moment the contract is signed and the crew schedule is locked.
We keep EcoTouch batts, FOAMULAR sheathing, and Duration shingles in rotation for active projects. For a full addition or ADU, we order the exact quantities to your project specs so nothing sits in a warehouse or gets substituted. You get a material list with your written quote, and we never swap brands without telling you first.
If your Owens Corning addition or ADU needs real work in Miami, call (850) 780-8123. Tell us what you need done. We’ll tell you what it costs and when it’s finished, and we’ll mean both.
Written by Isaac Pruett, Owner, Mason Remodeling Co Miami at Mason Remodeling Co Miami, serving Miami and nearby areas.
