Quick Answer: Container office soundproofing in Ontario typically targets STC 42 to 55 using a layered wall build: a 2×4 stud cavity packed with mineral wool, mass-loaded vinyl over the inside face, RC-1 resilient channel, and two layers of 5/8 inch drywall. That ladder takes a 20ft sea can from STC 25 bare to STC 55 in roughly 4 inches of build-out. Van Blanc has shipped containers across Ontario since 1995, with 4.9-star service and 1-3 day delivery from 4 Brantford yards.
In This Guide
- How Soundproof Is a Bare Shipping Container?
- What STC Rating Does a Container Office Need?
- The Five-Layer Office Wall Assembly We Spec
- How Mass-Loaded Vinyl and Decoupled Drywall Block Sound
- RC-1 Resilient Channel and Why Installation Quality Matters
- ASTC, Flanking Paths, and the Field-Rating Gap
- Phone Call Privacy: NRC Versus STC
- What STC Numbers Do Ontario Buyers Reference?
- Why the Door and Window Decide a Container Office’s Privacy
- What Drives the Cost and Lead Time of a Soundproof Office
- Frequently Asked Questions
Reading time: about 13 minutes.
How Soundproof Is a Bare Shipping Container?
A bare 20ft or 40ft shipping container sits around STC 25 to 30 with no interior build at all. STC 30 means a normal conversation is audible through the wall and roughly 75 percent intelligible. A phone call on one side of an unmodified container is a phone call you can mostly transcribe from the other side.
Corrugated Corten weathering steel is acoustically thin in the speech frequencies (125 Hz to 4000 Hz). The corrugations add stiffness but they also resonate. Every serious office conversion we ship out of Brantford starts from the same assumption: the steel skin is your weather barrier, not your acoustic barrier. The acoustic build sits inside the skin, fully decoupled from it where possible, which is the through-line in our full guide to building a container office in Ontario.
What STC Rating Does a Container Office Need?
Sound Transmission Class is a single-number summary of how well an assembly blocks airborne sound across speech frequencies. Every five-point step is meaningful; every ten-point step is dramatic.
A container office for normal phone-call privacy targets STC 45 to 50, where loud voices read as a faint murmur and normal speech disappears. Confidential work such as HR, financial advice, or counselling targets STC 50 to 55. Bare corrugated steel sits near STC 25.
Paul LeBlanc, owner, Van Blanc Ent. Inc.: “People ask me for a soundproof container like it is a single product on a shelf. It is a ladder. I have sold containers across Ontario since 1995, and the honest answer is that you pick the rung your work needs. A jobsite office and a counsellor’s room are not the same build, and pretending they are is how buyers overpay or underbuild.”
| STC Rating | Subjective Result on the Quiet Side | Realistic Container Office Build |
|---|---|---|
| 25 | Normal speech clearly audible and intelligible | Bare corrugated steel, no interior build |
| 30 | Normal speech audible, mostly intelligible | Bare container plus thin foam insulation |
| 35 | Loud speech audible, somewhat intelligible | Spray foam plus single 1/2 inch drywall, no decoupling |
| 42 | Loud speech audible as a murmur, not intelligible | 2×4 stud wall, batt insulation, single 5/8 inch drywall |
| 45 | Loud speech faint, normal speech inaudible | Stud wall plus mineral wool plus single 5/8 inch drywall plus acoustic sealant |
| 50 | Loud speech very faint, phone calls private | Stud wall, mineral wool, MLV layer, single 5/8 inch drywall |
| 55 | Loud speech inaudible, near-complete privacy | Stud wall, mineral wool, MLV, RC-1 channel, double 5/8 inch drywall |
| 60 | Confidential privacy threshold | Above what most container offices need or pay for |
Most Ontario buyers ordering an office container from us aim between STC 45 and STC 55. STC 45 covers normal open-plan office privacy. It is also the working office target where you want a closed-door space that handles a typical conversational phone call without bleed. At STC 50 a loud voice on the other side of the wall reads as a faint murmur, and a normal voice is gone. That is the line where a container office stops being a glorified shed and starts behaving like real office space.
The Five-Layer Office Wall Assembly We Spec
The build pattern below is what we hand off to the carpentry crew when an Ontario buyer asks for office-grade performance inside a 20ft or 40ft container. Each layer adds 3 to 10 points of STC depending on installation. Skipping any layer drops you a tier down the ladder.
- Mineral wool batt in a 2×4 stud cavity. Roxul Safe’n’Sound or equivalent at 3 inch thickness. Worth 5 to 8 STC points over an empty stud bay.
- Mass-loaded vinyl over the studs. 1 lb per square foot MLV as a continuous membrane on the interior face, seams overlapped and sealed with acoustical sealant. Adds 7 to 10 points on a metal-stud assembly.
- RC-1 resilient channel. Perpendicular to the studs, flange down, screwed only into the stud and never into the MLV. Worth 5 to 8 additional points if installed correctly, zero if short-circuited by a screw bridging through.
- Two layers of 5/8 inch Type X drywall. Staggered seams between layers, top layer screwed only into the resilient channel.
- Acoustic sealant at every perimeter. One unsealed gap the size of a pen drops the whole assembly 5 to 10 STC points.
Total interior build adds roughly 4 inches of thickness on each side of the container, trimming a 20ft from 7’8″ interior to roughly 7’0″. Buyers building for office-grade privacy almost always accept the trade.
The Cheapest 5 STC Points You Will Ever Buy
Acoustic sealant. A 20ft container office uses 6 to 10 tubes total around plates, penetrations, and electrical boxes. That hundred-dollar line item is worth more STC than half the products marketed as “soundproofing” online. Skip it and your STC 50 assembly tests at STC 42 in the field. Christian asks every install crew the same question before final inspection: “Show me the sealant beads.” If they cannot point at them, the wall is not done.
How Do Mass-Loaded Vinyl and Decoupled Drywall Block Sound?
Mass-loaded vinyl is a dense, flexible sheet (typically 1/8 inch thick, 1 lb per square foot) that adds mass without adding rigidity. The mass law of acoustics says that doubling the mass of a wall adds roughly 6 dB of transmission loss. MLV is the cheapest way to double the mass of a thin partition without rebuilding the structure.
On a wood-stud wall, 1 lb MLV typically lifts STC into the 40s. On a steel-stud wall, the same MLV layer can push STC into the mid-50s because steel studs conduct less vibration. Decoupled drywall is the second half of the equation. When drywall is screwed directly to a stud that is screwed directly to the container wall, you have a rigid path from inside-air to outside-air. Resilient channel, sound clips, or staggered-stud framing breaks that path so the drywall vibrates against a flexible component instead of against the steel container skin behind it.
Decoupling Without Resilient Channel
Sound isolation clips and hat channel (the Green Glue Whisper Clip system or the IsoMax pattern) outperform RC-1 in test labs by roughly 3 to 5 STC points. They cost more and demand more skilled installation. For most Ontario container office builds RC-1 is the right cost-performance balance. For recording-grade or counsellor-grade builds we spec in sound clips. We walk through that higher-end clip-based pattern in detail when we cover soundproofing a container into a music studio, where the low-frequency targets are far tougher than speech privacy.
RC-1 Resilient Channel and Why Installation Quality Matters
RC-1 was patented by USG in the 1960s and has been the industry-standard sound-isolating channel ever since. The geometry is simple: a thin steel hat-shaped section with a single attachment leg. The drywall hangs off the open side; the leg screws into the stud. The drywall pulls the channel away from the stud as it hangs, creating the small air gap that does the decoupling work. Installed correctly, RC-1 adds 5 to 8 STC points. Installed incorrectly, it adds zero or worse because the drywall double-bridges to the stud through both the channel screw and a direct screw the installer added by mistake.
The Six Installation Mistakes That Kill RC-1 Performance
- Screws bridging through. A drywall screw that hits the stud instead of the channel short-circuits the decoupling on the whole sheet.
- Wrong orientation. Flange must be down. Flange up turns the channel into a rigid bridge.
- Too few channel rows. 16 inch on-centre spacing maximum. 24 inch spacing fails.
- Channel screwed too tight to the stud. Overdriving the screw removes the flex that gives the channel its name.
- Channel run end-to-end without break. Long unbroken runs propagate vibration along the channel itself. Stagger and overlap.
- Caulking the gap. A bead of caulk between channel and stud restores the rigid bridge you just paid to remove.
Buyers who hire a general contractor unfamiliar with acoustic detailing end up with all six. Spec the build in writing before the crew starts, or hire an acoustic consultant for the inspection on confidential-grade builds.
ASTC, Flanking Paths, and the Field-Rating Gap
STC is a laboratory rating. ASTC (Apparent STC) is the field rating measured after the wall is built in the actual building, with the floors, ceilings, electrical penetrations, and adjacent structures connected to it. ASTC ratings are typically 3 to 7 points lower than lab STC on the same assembly. Sound finds the path of least resistance: through the floor underneath, through the suspended ceiling above, through the HVAC return shared with the adjacent room, through the conduit chase. Any of those flanking paths drops the apparent isolation below what the wall on paper promised.
The OBC 2024 ASTC Update
Ontario’s amended Building Code now references both STC and ASTC ratings. For multi-unit residential separations the code accepts an ASTC of 47 in lieu of a lab STC of 50, recognising that real-world flanking always pulls the field number down. A container office wall designed for STC 55 typically reads STC 48 to 52 in the field once floor, roof, and electrical penetrations are accounted for.
Container offices have an advantage here. The container itself is a sealed steel envelope. Flanking paths are limited to the floor (sound flanks through steel cross-members where the container sits on a concrete pad), the roof penetrations (vent stacks, conduit), and the door and window cuts. A single isolated office inside a 40ft container has no lateral shared wall to flank through.
Phone Call Privacy: NRC Versus STC
Buyers ask about NRC and STC interchangeably; they are not the same thing. STC measures sound transmission through a wall. NRC (Noise Reduction Coefficient) measures sound absorption within a room. For a phone-call-privacy office you care about both. STC keeps the call inside the room. NRC keeps the caller from sounding like they are in a steel box. A container office with STC 55 walls and an NRC 0.05 hard interior (bare drywall, steel ceiling) sounds private from outside but harsh on the call itself.
| Office Use Case | STC Target | NRC Target | Reasoning |
|---|---|---|---|
| Open-plan workstation | n/a (no wall) | 0.70+ ceiling, 0.60+ wall panels | Absorb sound, do not block it |
| Closed office, normal calls | STC 45-50 | 0.55+ ceiling tile, fabric chair | Phone audible only to caller, not next office |
| Closed office, confidential calls | STC 50-55 | 0.60+ ceiling, carpeted floor, panel art | HR, counselling, financial advisory |
| Counsellor or therapist room | STC 55-60 | 0.65+ ceiling, full acoustic panel walls | Speech Privacy Class confidential threshold |
| Sound booth or testing room | STC 60+ | 0.90+ on every surface | Beyond container-office scope, see music studio guide |
The National Research Council of Canada developed Speech Privacy Class (SPC) under ASTM E2638 to measure whether a casual listener can understand speech across a partition. Confidential SPC requires a Privacy Index of 95 percent: fewer than 5 words in 100 understood. Normal SPC requires 80 percent. Most container office buyers want normal; counsellors and HR professionals want confidential.
What STC Numbers Do Ontario Buyers Reference?
Ontario’s residential STC tables are the de facto benchmark container office buyers reach for, because every architect and contractor already knows them. A standalone accessory office container is not bound by those dwelling-unit numbers, but matching them voluntarily gives you a figure a planning officer, lender, or future buyer will instantly recognise.
OBC 2024 STC Reference Points
- STC 50 minimum between two dwelling units (the standard residential separation).
- STC 55 minimum between a dwelling unit and an elevator shaft or refuse chute.
- ASTC 47 minimum measured in-situ between dwelling units (effective minimum given flanking).
- Supplementary Standard MMAH SB-3 lists tabulated assemblies that meet the STC and ASTC minimums.
For an office in a working warehouse, a backyard ADU containing a home office, or a counsellor’s private practice container, the same STC 50 / ASTC 47 figure is what a planning officer or insurance inspector recognises. Hitting that line voluntarily keeps an inspector or future buyer from quibbling about acoustic performance.
Why Do the Door and Window Decide a Container Office’s Privacy?
A wall is only as private as its weakest section. In a container office the weakest section is almost always the door, second is the window, third is any HVAC penetration that bypasses the assembly. A hollow-core interior door tests around STC 20. A solid-core wood door tests STC 30 to 35. A solid-core door with a perimeter gasket and an automatic drop-down sweep at the bottom tests STC 35 to 40. A purpose-built acoustic door tests STC 45 to 55 and costs five to ten times what a hollow-core door costs. Most container office builds use a solid-core door with a full gasket kit, which lands them at STC 38 to 42.
A standard double-pane window tests STC 28 to 32. An acoustic window with laminated glass and a wider airgap tests STC 38 to 45. If your wall is built to STC 50 and your window is STC 30, apparent isolation of the wall-plus-window assembly drops to roughly the window’s rating across that section. In office-grade builds we typically spec a fixed acoustic-laminated unit, not a slider or casement, and the way that opening is cut and framed matters as much as the glass, which is why we treat cutting and sealing a window into the steel skin as part of the acoustic envelope rather than an afterthought. HVAC return ducts shared between rooms are the third flanker. A ducted return that runs from the conditioned room into a common attic space carries sound directly. Container offices that need real privacy use a through-wall mini-split or a dedicated PTAC unit, which eliminates the flank.
Christian LeBlanc, second-generation operator: “The wall is the easy part. We see buyers spend three months designing the perfect wall assembly and then put a hollow-core door on it because the carpenter had one in the truck. The door is the privacy. The window is the privacy. If a buyer tells me they want a real office-quiet container, the first question I ask is what door they are buying.”
What Drives the Cost and Lead Time of a Soundproof Container Office?
The build level you choose drives both the quote and the lead time on a soundproof container office. There is no single posted number, because the price moves with the container size and grade, the STC target, how many decoupling layers the assembly needs, and which trades finish the electrical and HVAC. The table below maps each build tier to its target STC, the layers that drive it, and a realistic build window once the container is on site.
| Build Level | Target STC | What Drives the Quote (20ft) | Build Window |
|---|---|---|---|
| Basic insulated office (single drywall, no MLV) | STC 40-42 | Stud wall, batt insulation, single drywall layer | 1-2 weeks |
| Standard office (single drywall + MLV) | STC 45-50 | Adds mass-loaded vinyl and acoustic sealant detailing | 2-3 weeks |
| Confidential office (double drywall + MLV + RC-1) | STC 50-55 | Adds resilient channel and a second drywall layer | 3-4 weeks |
| Sound-isolation clips upgrade (counsellor grade) | STC 55-58 | Swaps RC-1 for sound clips and hat channel, skilled labour | 4-5 weeks |
The container shell underneath all of this is usually a one-trip 20ft or 40ft, chosen for its clean steel and longest service life before the acoustic layers go in. Tell us the size, the STC target, and your postal code, and we send back an honest, all-in number rather than a posted figure that goes stale. We deliver the container in 1 to 3 days from our 4 Brantford yards, and the acoustic build adds 2 to 5 weeks depending on level. The order of operations, electrical, HVAC, and window cuts on the same shell, sits in our Ontario container office build guide, and the conversion work itself runs through our container modification and custom build program at the Brantford yard.
Worth the Drive for the Build Conversation
Buyers serious about acoustic-grade office builds visit our Brantford yard before they order. They want to walk a container, knock on the steel, hear the difference between bare and built. Worth the drive for unbeatable quality, family customer service with 30 years of experience. Every quote comes with a real lead time, not a hopeful one.
Ready to price your container?
Tell us the size and your postal code and we’ll send back an honest, all-in number, container, delivery, and placement, usually within 1-3 days. No pressure, no mystery fees.
Family-run in Brantford since 1995 · 200+ containers in stock · 4.9★ across 124+ Google reviews · every box graded by a person, walk it before it lands.
Frequently Asked Questions
What STC rating does a container office need for phone call privacy?
STC 45 to 50 handles normal phone-call privacy: loud voices inaudible, normal voices gone. STC 50 to 55 handles confidential calls including HR, financial, and counselling work. Below STC 40, adjacent occupants hear most of the conversation. Mass-loaded vinyl is the highest STC-per-dollar component in a container office build, and the layer we recommend first when budget is tight but privacy is critical.
Is RC-1 resilient channel worth the install complexity?
For office-grade builds aiming at STC 50 or higher, yes. RC-1 adds 5 to 8 STC points installed correctly and almost nothing installed incorrectly. Six common mistakes (wrong orientation, bridging screws, wrong spacing, overdriven screws, unbroken runs, caulking the gap) drop performance to zero. Hire a crew familiar with acoustic detailing or spec a clip-and-hat-channel system instead.
What is the difference between STC and ASTC ratings?
STC is a lab rating on the wall alone under ideal conditions. ASTC (Apparent STC) is a field rating measured in the installed building, accounting for flanking through floors, ceilings, ducts, and penetrations. ASTC is typically 3 to 7 points below STC on the same assembly. Ontario’s 2024 Building Code recognises both, accepting ASTC 47 in lieu of STC 50 for residential separations.
How thick is a typical container office acoustic wall build?
A standard STC 50 build adds roughly 4 to 4.5 inches on each side of the container: 2×4 stud cavity (3.5 in), MLV (1/8 in), RC-1 channel (1/2 in), and double 5/8 in drywall (1.25 in). That trims a 20ft from 7’8″ interior to roughly 7’0″. Most office buyers accept the trade for the acoustic performance.
Does spray foam insulation soundproof a container office?
Not on its own. Closed-cell spray foam adds 2 to 4 STC points by killing the steel skin’s resonance. To reach office-grade STC you need spray foam plus a separate stud wall with mineral wool, MLV, and decoupled drywall. Spray-foam-only office builds test at STC 35 to 38, below normal conversational privacy.
What kind of door do I need for a confidential container office?
A solid-core wood or steel door with a perimeter gasket kit and an automatic drop-down sweep at the bottom. That setup tests STC 38 to 42 and is the working office-grade door for most Ontario container conversions. Purpose-built acoustic doors test STC 45 to 55 but cost five to ten times as much. The door caps the privacy of the wall section it sits in, so do not put a hollow-core door in an STC 50 wall.
Can I get container office soundproofing done in Ontario by Van Blanc?
We deliver the container and partner with regional carpentry and electrical crews on the acoustic build. Buyers in Greater Brantford, Hamilton, KW-Cambridge, and the GTA corridor see the fastest turnaround. Buyers further afield use our delivery plus their own local contractor with our spec sheet in hand. Stand-alone accessory office containers (backyard work-from-home, jobsite, agricultural) are not directly bound by Section 9.11 STC rules. Most planning officers still use STC 50 as the de facto benchmark.
How is a container office STC build different from a music studio STC build?
A music studio targets STC 60 to 70 because low-frequency content (kick, bass, monitor sub) requires double-stud walls, room-within-a-room construction, decoupled floor, and sealed acoustic doors. A container office targets STC 45 to 55 because speech frequencies (125 Hz to 4 kHz) are the only privacy concern. Office builds use one wall layer and one decoupling system; music studio builds use two of each.
Sources
- Government of Ontario. (2024). Building Code (O. Reg. 332/12), Section 9.11 Sound Transmission and Supplementary Standard SB-3. ontario.ca/laws/regulation/120332
- National Research Council of Canada. (2018). Speech Privacy Class (SPC) and the IRC Soundscape Research Program. nrc-publications.canada.ca
- ASTM International. (2019). ASTM E90-09: Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions. astm.org/e0090-09r16
- ASTM International. (2020). ASTM E336-20: Standard Test Method for Measurement of Airborne Sound Attenuation between Rooms in Buildings (ASTC). astm.org/e0336-20
- Acoustical Solutions. (2025). 5 Strategies to Achieve STC 50 and Above in Modular and Commercial Builds. acousticalsolutions.com/stc-rating-50
Reach Van Blanc in Brantford
We have been supplying shipping containers across Ontario since 1995. Our warehouse is at 90 Morton Avenue E in Brantford, and we deliver right across the province on a cash-on-delivery basis. No surprise fees, no chase-the-paperwork.
Van Blanc Ent. Inc. 90 Morton Ave E Unit 1B, Brantford, ON N3R 7J7 +1 888-509-6658
If you are planning an office-grade acoustic build, come walk a finished demonstrator at the yard. The difference between a bare 20ft and a built 20ft is something you hear with your hand on the wall, not from a spec sheet.
Placement requirements vary by municipality. A quick call to your local planning office before delivery is the easiest way to confirm what works for your property.