Signs you need this
- • Commercial: permit drawings call out a UL design number that doesn't match what was roughed in
- • Commercial: an AHJ inspector flags a demising wall or stairwell enclosure as non-compliant
- • Commercial: CO closeout is stalled because the fire-rated assembly documentation is incomplete
- • Residential: a buyer's attorney or home inspector flags garage drywall as missing or non-Type X
- • Residential: a lender or insurer requires documented garage fire separation before closing
- • Residential: the attached-garage walls were finished with standard drywall, not Type X
What the service involves
A fire-rated assembly is a UL-listed system — a specific design number that dictates board type, stud gauge, fastener schedule, and joint treatment to achieve a tested fire-resistance rating. We install Type X and Type C assemblies to the listed specification for commercial demising walls, corridors, and stairwells, and correct non-compliant residential garage assemblies before closing — with full CO documentation for the closeout file.
What a UL design number actually specifies
The UL Fire Resistance Directory lists hundreds of tested assembly designs, each tied to a specific combination of materials and construction details. A design number might specify 5/8” Type C board on each side of 3-5/8” 20-gauge steel studs at 16” o.c., with a specific fastener size and spacing, a specific joint treatment, and a tested fire-resistance rating of 1 or 2 hours. Substituting 25-gauge studs, using Type X instead of Type C, or changing the fastener pattern all void the rating — not slightly reduce it, void it entirely. When the AHJ inspector shows up for the rated wall inspection, they’re checking that the built assembly matches the design number on the permit. “I used fire-rated board” doesn’t satisfy that inspection.
Commercial: demising walls, corridors, and stairwells
In commercial TI work, fire-rated walls are typically required between tenant suites (demising walls), at corridor separations, and at stairwell and elevator enclosures. The governing IBC section and occupancy classification determine the required rating — typically 1-hour or 2-hour. We identify the applicable section from the project drawings, select the correct UL design, and confirm with the GC before framing. We pull the sub-permit, install to the design specification, document the assembly (UL number, board manufacturer and product name, stud gauge, fastener schedule), and coordinate the AHJ inspection before the walls are finished. The documentation package goes into the GC’s CO file.
Residential: garage-to-living-space separation
Connecticut residential code requires a fire-rated separation between an attached garage and any habitable space. The common wall between the garage and the house requires 5/8” Type X drywall on the garage side. The ceiling of the garage below a habitable room also requires 5/8” Type X. Standard 1/2” drywall in either location is non-compliant.
This is the most common fire-rated issue we see in Fairfield County residential work, and it almost always surfaces as a pre-closing issue rather than during renovation. A buyer’s attorney or home inspector flags the garage during due diligence — 3–6 weeks before the scheduled closing — and the seller needs it corrected on a tight timeline. The correct fix is tearout and reinstall with the right product. Adding a layer of Type X over existing non-rated drywall in the garage does not produce a compliant assembly; the existing board is still there, and the fire-resistance calculation requires the correct assembly from the substrate out.
Documentation and inspection
For both commercial and residential fire-rated work, we produce written documentation of the installed assembly: UL design number, board manufacturer and product name, stud gauge and spacing, fastener schedule. For commercial jobs, this goes to the GC for the CO closeout file. For residential pre-closing work, we produce a written record for the title company and attorney’s file. The AHJ inspector needs to verify the design number against the installation — documentation is what makes that inspection pass.
Materials & standards
Products & materials we use
- USG Firecode (Type X)
- USG Firecode C (Type C)
- National Gypsum Gold Bond Fire-Shield / Fire-Shield C
- CertainTeed Type X
- Durabond / Easy Sand (setting compound)
Standards & codes we work to
- UL Fire Resistance Directory / design numbers (e.g., U305, U419)
- IBC Section 709 (fire partitions) / 707 (fire barriers) / 722
- 2022 Connecticut Building Code (IBC 2021)
- GA-216 (joint treatment in listed assemblies)
What the terms mean
- Fire resistance rating (1-hour / 2-hour)
- UL-listed assembly
- AHJ (Authority Having Jurisdiction)
- Type X / Type C drywall
- Demising wall / occupancy separation
- Garage common wall
- Fastener schedule
- 25- / 20-gauge steel stud
- Point-of-sale inspection
- CO documentation package
Options & variants
| Option | When it applies | Cost |
|---|---|---|
| Commercial 1-hour fire partition | Demising walls between suites, corridor walls in office buildouts | Mid |
| Commercial 2-hour fire barrier | Stairwell enclosures, occupancy separations | Higher |
| Commercial corridor wall assembly | Egress corridor separations per occupancy type | Mid–high |
| Multifamily demising wall | Party walls at Harbor Point / condo, often with acoustic requirements | Highest (fire + acoustic) |
| Residential garage common wall (no tearout) | Attached garage sharing a wall with living space; 1/2-inch Type X on the garage side | Low |
| Residential garage wall with tearout | Existing non-compliant board must come out before Type X reinstall | Moderate |
| Above-garage ceiling assembly | Habitable space above the garage; 5/8-inch Type X on the garage ceiling | Moderate–high |
What affects cost
- • Linear feet of fire-rated wall — the primary commercial cost driver.
- • UL design number complexity — a 1-hour single-layer assembly uses less material than a 2-hour double-layer.
- • Type C vs. Type X board — Type C costs more and is required for certain UL designs; substituting it is a code failure.
- • Framing gauge — 20-gauge steel stud costs more and installs slower than 25-gauge.
- • Demolition of non-compliant assembly — residential tearout adds labor and disposal before reinstall.
- • Sub-permit and inspection coordination — commercial fire-rated work requires a permit.
- • CO documentation package — assembling the UL design file, spec sheets, and fastener schedule prevents CO delays.
- • Wall height — commercial walls above 10 feet may require bridging or heavier framing.
Price ranges
Residential — garage wall, no tearout
$700–$2,200
Standard attached 1-car garage, 1/2-inch Type X on the garage side, no board removal.
Residential — garage wall with tearout
$1,000–$3,000
Same scope plus removal of non-compliant existing drywall before Type X reinstall.
Residential — above-garage ceiling
$1,200–$4,500
Larger ceiling area in 5/8-inch Type X; driven by garage footprint.
Commercial — 1-hour fire partition
$2,500–$15,000
Per tenant suite; single-layer Type X or C, 25-gauge framing, sub-permit, documentation package.
Commercial — 2-hour fire barrier / stairwell
$6,000–$35,000+
Double layer, 20-gauge framing, full UL compliance; stairwells and occupancy separations at the high end.
What to expect
- 1
Commercial: scope and code review
We identify every wall requiring a rating, referencing IBC 709 (fire partitions) and 707 (fire barriers) against occupancy, and select a UL design if the drawings don't specify one.
- 2
Commercial: UL design number selection
We pull the specific UL Directory design for each assembly — board type, stud gauge, fastener size and spacing, joint treatment. Nothing is field-improvised.
- 3
Commercial: sub-permit pull
We pull the sub-permit and coordinate the inspection schedule with the Stamford Building Department so the GC's schedule isn't disrupted.
- 4
Commercial: framing and board to spec
Correct gauge and stud spacing, then correct board type, fastener pattern, and layering per the listing — no field substitutions.
- 5
Commercial: joint treatment and AHJ inspection
Tape and compound per the listing; the AHJ inspects before the assembly is concealed.
- 6
Commercial: CO documentation package
UL design number, board type and manufacturer, framing spec, and fastener schedule delivered for the GC's CO file.
- 7
Residential: on-site assessment
We check the garage common wall and ceiling, identify existing board type, confirm whether habitable space is above, and determine the required thickness.
- 8
Residential: written quote
Specifies board type, area, whether tearout is required, and the code basis — no ambiguity about what's installed.
- 9
Residential: tearout (if required)
Non-compliant board comes out before Type X goes in; adding a layer over standard drywall is not compliant. We document what was removed.
- 10
Residential: Type X installation and documentation
Correct thickness and fastener schedule to a listed assembly, taped and finished; written record of board type, UL reference, and date for the attorney, lender, or AHJ.
When this isn’t the right call
- If the project requires sprinklers → fire suppression is a separate contractor; we coordinate with the GC's mechanical subs but don't scope sprinklers.
- If the commercial space has no rated-wall requirements → standard commercial drywall is the right scope; we review drawings before quoting.
- If existing garage drywall just needs cosmetic repair → if it's already correct Type X and sound, patching is the right call, not reinstall.
- If the garage is detached → detached garages don't require fire separation from the house under the same provisions.
Frequently asked questions
What's the difference between Type X and standard 5/8-inch drywall — can't I just use regular 5/8-inch? +
No. Type X has glass fibers in the gypsum core that give it fire-resistance performance; standard 5/8-inch board is the same thickness but not the same composition. An assembly built with standard board doesn't meet the UL rating even if it looks identical. In residential garages this is the most common failure — a prior owner used standard 5/8-inch, and an attorney or inspector who asks for the spec will catch it.
What is a UL design number and why does it matter for my commercial project? +
The UL Fire Resistance Directory catalogs fire-tested assemblies, each with a design number (e.g., U305, U419) specifying exactly how it must be built — board type, stud gauge, fastener size and spacing, joint treatment, layers — to achieve the rating. A 1-hour fire partition has to be built to a specific design number. The Stamford AHJ will ask for it; a fire-rated-looking wall without a listed design can't demonstrate compliance.
Can I add a layer of Type X over my existing garage drywall to make it compliant? +
No. Laminating over non-rated board is not a listed configuration — the UL assembly specifies the whole system from the substrate out. The correct fix is tearout of the existing board and reinstall of the correct Type X product to the listed assembly. That's also what an attorney or inspector expects documented.
My buyer's attorney flagged my garage fire-rated drywall at closing. How fast can this be done? +
A standard attached garage (one car, common wall only) can usually be assessed and scheduled within a week and completed in one to two days; add a day if existing board needs to come out. We provide written documentation of the assembly — board type, UL reference, install date — which is what attorneys and lenders request. Call as soon as it's flagged.
What's the difference between a fire partition (Section 709) and a fire barrier (Section 707)? +
Both are fire-resistant walls with different purposes. Fire partitions (709) are tenant separations in sprinklered buildings and corridor walls — typically 1-hour, fewer continuity requirements. Fire barriers (707) are occupancy separations, stairwell enclosures, and shaft walls — typically 1- or 2-hour with stricter rules for connecting to the floor and structure above. Which governs depends on occupancy and the wall's function.
Does my Stamford commercial TI project require a permit for fire-rated wall work? +
Yes. Commercial TI requires a building permit, and fire-rated assemblies are specifically reviewed and inspected before they're concealed. We pull the sub-permit and coordinate the inspection directly with the Stamford Building Department; the documentation is part of the CO closeout record.
What is Type C drywall and when is it used instead of Type X? +
Type C — USG Firecode C, National Gypsum Fire-Shield C — exceeds Type X fire performance through additional glass fibers and a more stable core under heat. It's used where longer ratings are needed with a single layer, or where Type X would require an extra layer. The UL design specifies which is required; they're not interchangeable, and Type C costs more per sheet.
Does fire-rated assembly affect the acoustic performance of the wall? +
Fire and acoustic ratings address different things and don't automatically come together — a wall can be fire-rated but acoustically transparent. On demising walls in Stamford buildouts and Harbor Point multifamily, we specify assemblies that satisfy both STC and fire performance where required; these are listed in the UL directory and usually use a double-layer system.