An ACM rainscreen system puts aluminum composite panels in front of a drained, ventilated space, and the decision that shapes everything else is how the joints between panels are closed. In a wet-seal system every joint gets backer rod and sealant, so the panel face is the main weather line. In a dry-joint system the joints stay open or gasketed, and the air and water barrier behind the panels does that job.
Both can look sharp on a storefront, fascia, canopy or building entrance. They differ in upkeep, in how they handle movement, in how they meet windows and coping, and in how they fit the fire-tested wall assembly your building may need. This guide lays out those differences for New Jersey owners, architects, general contractors and panel installers working with aluminum composite panels. Architectural Metal Panels fabricates the panels in its New Jersey shop to approved shop drawings; the wet-seal or dry-joint system is installed on site by your installer.
What is the difference between wet-seal and dry-joint ACM?
Wet-seal closes every reveal with sealant; dry-joint leaves the reveals open or fitted with gaskets or extrusions and manages water behind the panels. Strictly speaking, wet-seal is a face-sealed barrier wall with a backup barrier, while dry-joint is a true rainscreen.
Both start the same way. In the shop, each panel is routed on the back and folded into a tray to the approved shop drawings, ready for the clips or perimeter extrusions of the chosen system. This route-and-return method gives the panel stiff returned edges. What happens at the joint is where they part ways.
| Factor | Wet-seal | Dry-joint |
|---|---|---|
| Joint | Backer rod and sealant in every reveal | Open reveal, gasket or extrusion, with no field sealant at the joints |
| Main weather line | Panel face and sealant, with a barrier behind as backup | Air and water barrier behind the panels; panels shed most of the rain |
| Look | A sealant line in each reveal, usually color-matched | A crisp shadow line at each reveal |
| Upkeep | Sealant joints need periodic inspection and eventual replacement | Little joint upkeep, but the hidden barrier and flashings must be right the first time |
| Barrier behind | Standard water-resistive barrier | A barrier rated for open-joint exposure, per its maker |
| Installer’s cost drivers | Field sealant labor and lift time | Clip or extrusion system and barrier detailing |
How does a wet-seal ACM system work?
The installer hangs the trays on clips or angles fixed to the wall and fills the reveals between them with backer rod and sealant. The sealed face sheds the rain, and any water that gets past a joint is meant to be stopped by the barrier behind.
The sealant does the hard work, so the joint design matters. The reveal has to be wide enough for the sealant to stretch as each panel grows and shrinks with temperature. The sealant has to be compatible with the panel finish, applied with the primer its maker calls for, and tooled to the right depth.
Sun, freeze-thaw cycles and movement age every sealant joint. Plan on regular inspections and on replacing joints as they fail. That upkeep is easy at a one-story fascia and expensive on an upper floor that needs a lift.
Wet-seal suits small, reachable areas: sign bands, fascias, column covers, canopy edges and storefront surrounds. It also suits re-cladding work where wall depth is tight.
How does a dry-joint rainscreen work?
Panels hang on a subframe or extrusion system with open or gasketed reveals, leaving a space behind them that drains and ventilates. Most rain hits the panel face and runs off, and the small amount that enters a joint drains down the cavity and out at the base.
Because the joints are open, the wall behind them carries the real weather protection. A dry-joint wall needs:
- A continuous air and water barrier, lapped and sealed at every opening
- A barrier product its maker accepts behind open joints, where it sees daylight and weather
- Flashings at window heads, floor lines and the base that throw water back out
- A clear drainage path at the bottom, screened against insects
- A subframe aligned flat enough that the reveals stay straight
Dry-joint suits taller elevations, entrances where a sharp reveal is part of the design, and buildings where future sealant work would be hard to reach.
Which ACM joint system meets New Jersey fire code?
Neither joint type passes or fails on its own. Fire rules look at the panel core and the whole wall assembly, including insulation and barrier, and the answer depends on construction type and height.
New Jersey adopted the 2024 International Building Code, with state amendments, effective August 17, 2026 (NJ DCA adoption notice). The IBC has a dedicated section for metal composite material wall panels. An ICC overview explains that, on Type I-IV construction, MCM installed without a height limit generally must pass NFPA 285 fire-propagation testing. Code alternatives allow some installations up to 40 feet above grade without that test when flame-spread and coverage limits are met.
Insulation changes the picture too. The same ICC article notes that when foam plastic insulation is part of an exterior wall on a Type I-IV building over one story, the IBC generally requires the assembly to comply with NFPA 285. The exception is foam covered on each face by masonry or concrete. A dry-joint wall with foam board in the cavity has to match a tested assembly, not just a tested panel.
Fire-rated core panels are available where the design calls for them. The architect or code consultant sets the requirement and the tested assembly. We quote and fabricate the panel core the drawings call for; ask for the panel manufacturer’s test reports with your submittal request.
Which system holds up better in New Jersey weather?
Both handle New Jersey weather when they are detailed well. The difference is where the risk sits: on a wet-seal wall it sits in the sealant you can see, and on a dry-joint wall it sits in the barrier and flashings hidden behind the panels.
Wind drives rain into joints on exposed elevations, and winter brings repeated freezing and thawing. Clip spacing and attachment are designed for the wind load at the site. New Jersey guidance in DCA Bulletin 19-1 tells designers to take wind values from ASCE 7-based tools for the exact address.
Near the shore or heavy industry, ask the panel maker how its finish warranty treats that exposure, since terms are written per product. Energy rules matter as well: new buildings and additions document Energy Subcode compliance, while repair and alteration work follows the Rehabilitation Subcode, according to DCA Bulletin 22-1. Ask the architect which path applies before the cavity depth is fixed.
What drives the price of an ACM rainscreen system?
There is no reliable published per-square-foot figure for ACM, because no reputable cost guide covers it and scopes vary widely. The panel price follows the drawings, and the installed cost adds the work your installer prices.
What sets the price of the fabricated panels?
- Panel module sizes and how efficiently they cut from stock sheets
- Corners, soffits, returns and column covers, which take more shop time than flat field panels
- Standard or fire-rated core
- Finish, including metallic and custom colors
- Matching trim, flashing and coping on the same order
What does the installer price?
- Subframe, insulation and barrier scope
- Access: lifts, scaffold and sidewalk protection in busy downtowns
- Sealant labor for wet-seal, or the clip and extrusion system for dry-joint
Send drawings and the wall panel spec section through our plans for a quote page. We reply with a written quote or questions for the fabricated panels, trim and coping, and we prepare shop drawings for approval before fabrication. Our resources for contractors and builders explain how drawings, approvals, delivery and pickup work.
How do you choose between wet-seal and dry-joint?
Choose by design intent, building height and the tested assembly first, then by the upkeep the owner can support.
- Pick dry-joint when the design wants a crisp reveal, the elevation is tall or hard to reach, or the owner wants to avoid future sealant work.
- Pick wet-seal for small, reachable areas such as sign bands, fascias, column covers and canopy edges, or where wall depth is limited.
- Match the joints to the windows. The storefront or window system and the panel barrier must lap correctly at every head, jamb and sill.
- Detail the top and bottom. At the roof edge the panels meet the metal coping, which must lap the panel and shed water outward. At grade, the base needs a drip and clearance.
Re-cladding an existing building has one more check. Under N.J.A.C. 5:23-2.7, replacing siding with like material on buildings other than one- and two-family homes counts as ordinary maintenance only up to 25 percent of the wall area. A new ACM system is rarely a like-for-like swap, so the owner and installer should plan on a permit and confirm with the local construction office. Related trim and soffit parts come from our custom fabrication shop, and the wider panel line is on our metal wall panels page.
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ACM rainscreen questions
Is wet-seal ACM a true rainscreen?
Not strictly. In a wet-seal system the sealed panel face is the main weather line, so it works as a face-sealed barrier wall with a backup barrier behind it. A dry-joint system is the true rainscreen, because it expects some water in the joint and drains it from the cavity.
Do dry-joint ACM walls leak through the open joints?
Some water enters an open joint by design. The cavity drains it out at flashings and the base, and the air and water barrier keeps it off the wall. Leaks come from gaps in that barrier or missing flashings, not from the open reveal itself.
How long do sealant joints on a wet-seal ACM wall last?
It depends on the sealant, the joint design, sun exposure and movement. Plan on regular inspections and replacement of joints as they fail. The sealant maker’s data and the original joint design are the best guide for a specific wall.
Does an ACM wall need NFPA 285 testing in New Jersey?
It depends on the construction type, the height, the panel core and the rest of the wall assembly, including any foam insulation. New Jersey enforces the International Building Code with state amendments, and the 2024 edition took effect August 17, 2026. The architect or code official sets the requirement for each building.
Can ACM panels go over an existing brick or block wall?
Often, yes. Your installer anchors a subframe through to the structure, adds a barrier and hangs the panels on the subframe. The existing wall has to be checked for soundness and anchorage, and the added depth changes the window and coping details on the shop drawings.
What should I send to get an ACM rainscreen priced?
Send elevations, wall sections, the panel spec section, the finish and core requirements and the bid date. We quote the fabricated panels, trim and coping; your installer prices the installation. If the joint system is not decided yet, say so and ask for both options to be quoted.
Builders and architects
Have ACM on your drawings?
Send the elevations and the panel spec section. Architectural Metal Panels quotes the routed and folded ACM panels, trim and coping, prepares shop drawings for approval and flags joint details that need an answer before fabrication. Orders are delivered in New Jersey or picked up at our shop.
