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Owens Corning Home Additions & ADU: The Jacksonville Owner’s Guide
If you’re planning a home addition or ADU in Jacksonville and want Owens Corning insulation and building materials specified throughout, a full project typically runs $45,000 to $130,000 installed, depending on square footage, foundation work, and finish level. We stock and install Owens Corning insulation, roofing underlayment, and weather barrier products as part of our home addition and ADU builds across Jacksonville, and we can usually match your existing Owens Corning specs from the original build within a few days of the estimate.
Most homeowners come to us after they notice uneven room temperatures in a new addition, high summer cooling bills, or dampness along the new wall line where the addition ties into the existing structure. That’s usually an insulation gap, a failed air seal, or an under-specified vapor barrier, and it’s the kind of thing that gets expensive if it’s ignored through one Jacksonville summer.
Key Takeaways:
- Home additions with Owens Corning products in Jacksonville typically cost $45,000 to $130,000 installed.
- We match existing Owens Corning insulation and weather barrier specs so the new section performs like the original build.
- Every project gets a written price before work starts, and it doesn’t move at the door.
- All completed work carries the 365-Day Done Right Promise in writing.
Which Owens Corning Models This Applies To
Owens Corning doesn’t make “models” of home additions, but it does make the building envelope products that determine whether your Jacksonville addition stays cool, dry, and structurally sound. The relevant product lines are PINK Fiberglas batt insulation (R-13, R-19, R-30, and R-38 are the common specs for Florida wall and attic assemblies), FOAMULAR rigid foam board for slab edge and below-grade applications, and the Owens Corning Deck Defense or ProArmor roofing underlayment if the addition includes a new roof plane.
The compatibility gotcha we see in Jacksonville is this: Florida building code requires R-38 minimum in vented attics, but many older homes were built with R-19 or R-30. If you’re adding onto a 1990s home and the new attic gets R-38 batt while the old attic is under-insulated, you’ll feel the difference at the transition wall every August. We check what’s already in the existing attic and spec the addition so the whole envelope performs as one system, not two different buildings sharing a wall.
On the OEM versus aftermarket decision: Owens Corning batt insulation is a commodity product with published R-values and a limited lifetime warranty, so there’s no real aftermarket equivalent to worry about. What matters is that the installer actually hits the labeled R-value, which means proper installation depth, no compression, and clean cuts around electrical boxes. That’s where we spend our time on the job. For rigid foam below slab, we spec Owens Corning FOAMULAR 250 or 400, because the compressive strength rating matters when you’re putting a conditioned ADU on a slab in Jacksonville’s sandy soil.
Styles & brands we work with
Signs Your Owens Corning Home Additions & ADU Is Failing
- One room in the addition never holds temperature. This usually means a batt was compressed behind a wire, or there’s a void above a window header. The fix is targeted, not a full re-insulation, but you have to open the wall to find it.
- Condensation on the inside of new windows in winter. Florida homes don’t get real winter, but Jacksonville gets enough cool mornings that a missing vapor barrier shows up as interior glass sweating. That’s warm, humid interior air hitting a cold surface, and it points to an air seal failure at the window rough opening.
- Musty smell along the baseboard where the addition meets the original slab. That’s moisture wicking up through a slab edge that wasn’t insulated or sealed properly. You’re smelling the beginning of a mold problem, and it rarely dries out on its own in Jacksonville humidity.
- Cooling bills jumped after the addition was completed. If the new space doubled your square footage but your bill tripled, the addition’s envelope is leaking. A blower door test will find it in under an hour.
- You can see daylight around a can light or ceiling box in the addition. That’s an uncompressed air path straight into the attic. Every one of those is a hole in your thermal envelope, and together they add up to the equivalent of leaving a window cracked all year.
See the difference
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After
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AfterReplacement Cost & What’s Included
For a new home addition or ADU in Jacksonville where Owens Corning insulation and weather barrier products are specified throughout, you’re looking at $45,000 to $130,000 installed. The spread is driven by square footage, whether you’re building on a slab or a raised foundation, how much structural work is needed to tie the new roof into the existing one, and the finish level inside.
Here’s how the major pieces break down on a typical Jacksonville home addition:
- Foundation and slab work: $8,000 to $25,000 depending on soil conditions and whether piers are needed
- Framing, sheathing, and roof structure: $15,000 to $40,000 based on the roof line and tie-in complexity
- Owens Corning insulation package (walls, attic, slab edge): $2,500 to $8,000 depending on R-value specs and square footage
- Mechanical rough-in (electrical, HVAC, plumbing if applicable): $8,000 to $25,000 depending on how far the existing systems have to reach
- Drywall, trim, paint, and finish work: $10,000 to $30,000 for a standard finish package
Every number above is a line item on a written estimate before we start. No allowances that turn into change orders. No “we’ll figure it out when we get there.” Curtis Lane locks the scope before the first nail goes in, and the price you sign is the price you pay at closeout, unless you change the scope yourself and sign off on the change in writing.
The 365-Day Done Right Promise covers every completed project. If any part of the addition fails inside that first year, whether it’s a sagging door, a drywall crack at the tie-in, or an air leak in the new envelope, we come back and correct it at no charge. That guarantee is in writing, in your hand, before we start the job.
DIY or Call Us?
If you’re diagnosing an existing addition, there are a few things you can check yourself without opening anything up. Walk the exterior wall line and look for gaps where the new siding meets the old. Check that all foundation vents are open and clear. Inside, hold a damp hand near window frames and outlet covers on a humid day and feel for air movement. Those checks will usually tell us where to start looking.
What you shouldn’t do is open a wall to inspect or replace insulation yourself if you suspect a moisture problem. Jacksonville humidity means what’s behind that drywall could be mold, and cutting into it without knowing what you’re releasing is a health risk you don’t want in your house. Cutting batts and installing them is one thing. Cutting into a wall that’s been holding moisture for a season is another.
If it’s a new addition or ADU, that’s a full build. Permits, structural tie-ins, roof plane transitions, and the Florida energy code compliance that goes with them. That’s not a weekend job, and it’s not something we’d recommend anyone try without a general contractor on record. Call us at (904) 337-5929 and we’ll walk the site, give you a written scope, and price it honestly.
FAQs
Owens Corning fiberglass batt insulation carries a limited lifetime warranty and does not degrade or settle under normal conditions, so it should perform for the life of the structure as long as it stays dry. In Jacksonville, the real variable is moisture, not age. A properly sealed and insulated wall cavity in a Jacksonville addition will still be performing 30 years from now. Call (904) 337-5929 if you suspect moisture has compromised your existing insulation, and we’ll inspect it.
Yes, most insulation failures in additions are localized voids, compressed batts, or air seal gaps that can be repaired without a full re-insulation. What determines whether repair works is whether the surrounding insulation is still dry and properly installed. If moisture has wicked through a section, that section gets pulled and replaced, not patched. Call (904) 337-5929 and we’ll tell you exactly what needs to come out and what can stay.
A standard single-story addition in Jacksonville takes 3 to 6 months from permit to final inspection, and an ADU typically runs 4 to 8 months depending on site conditions, utility connections, and the finish schedule. Jacksonville’s permitting process moves at its own pace, and we sequence rough-in inspections so we’re not waiting on the city with an idle crew. Call (904) 337-5929 and we’ll give you a realistic timeline for your specific project before you commit to anything.
We stock common Owens Corning R-19 and R-30 batt insulation, FOAMULAR rigid foam in standard thicknesses, and ProArmor roofing underlayment at our Jacksonville location, so most projects start within a week of contract signing. Non-standard R-values or specialty board thicknesses get ordered direct, which usually adds three to five business days. Call (904) 337-5929 and we’ll confirm availability for your spec before the estimate is even written.
If you’re planning a home addition, ADU, or garage conversion in Jacksonville and want Owens Corning products specified throughout, call (904) 337-5929. We’ll walk the property, write the scope, give you a firm price, and put the 365-Day Done Right Promise in your hand before a single tool comes off the truck. Bradford Remodeling Co Jacksonville is an independent contractor, not affiliated with Owens Corning, but we spec and install their products because they hold up to Jacksonville’s heat and humidity better than most of what’s on the shelf.
Written by Curtis Lane, Owner, Bradford Remodeling Co Jacksonville at Bradford Remodeling Co Jacksonville, serving Jacksonville and nearby areas.
