SnoBar Double Bar Screw Down Snow Rail for Exposed Fastener Metal Roofs - Galvanized, 6 Foot
The heavy-duty double bar snow retention system built for exposed fastener metal roofs. Two Gator Shield galvanized 1" square bars mechanically fasten through the panel into a structural purlin - the correct snow rail system for PBR, AG panel, 5V Crimp, Tuff Rib and other screw down metal roof profiles where clamp-on snow guards will not work.
❗ Important: Full Roof Coverage Required ❗
This system is not designed for isolated roof areas - do not install only over doorways, walkways, vents, or partial roof sections. Snow above an isolated bar run still slides, ramps over the barrier, and releases in one concentrated mass. Effective snow retention requires continuous rows across the entire roof plane. For any partial-area application, contact us for special design considerations before ordering.
Why Contractors Specify the Double Bar Screw Down SnoBar
- Double bar capacity - two continuous 1" square bars per row for higher snow load.
- Gator Shield galvanized coating with 50% more zinc than standard galvanizing
- Built for exposed fastener metal roofing - PBR, R-panel, AG panel, 5V Crimp, Tuff Rib, Classic Rib, U-panel and similar through-fastened profiles
- 16-gauge Gator Shield steel bars paired with mill aluminum brackets that will not rust or corrode
- Project-specific spacing layout guidance with every order - eliminates guesswork on row count and bracket spacing
- Made in the USA with 30+ years of laboratory and field-proven performance behind every component
Product Overview
The SnoBar Double Bar Screw Down Snow Rail is the heavy-duty configuration of the original SnoBar snow retention system, purpose-built for exposed fastener metal roofs. Two Gator Shield galvanized 1" square steel bars run continuously across the roof, mechanically fastened through the panel into the structural purlin below. Contractors specify this double bar configuration when single bar snow rails may not provide enough retention for the roof conditions - commercial buildings, steep-slope roofs, heavy-snow regions, and any roof where a slide event creates liability exposure.
This is the correct snow retention system for metal roofs that use exposed fasteners rather than concealed-fastener standing seam. Screw down panels - PBR, R-panel, AG panel, 5V Crimp, Tuff Rib, Classic Rib and similar ribbed through-fastened profiles - do not have the raised seam geometry that clamp-mounted snow guards require. The proper attachment on these roofs is a mechanically fastened bracket (MRM BRACKET) that penetrates the panel and anchors into the purlin.
How the Double Bar Snow Rail System Works
A properly designed snow retention system distributes retained snow load evenly across the entire roof plane. Continuous snow bars in rows from eave to ridge hold accumulated snow and ice in place so it melts and releases gradually rather than sliding off as an avalanche. When every panel carries its share of the load, no single fastener, purlin, or panel section is overloaded.
Double bar outperforms single bar for three reasons. Cross-sectional area - two 1" square bars present roughly twice the physical barrier to sliding snow. Load distribution - retained snow transfers into the brackets across two bearing surfaces instead of one, reducing point stress at each attachment. Slide behavior - the lower bar catches the initial slide event, the upper bar stops any snow that rides over the first. On commercial roofs, steep pitches, and heavy-snow regions, this is what separates a system that holds from one that fails.
What's Included
- (2) 6-foot 1" square Gator Shield galvanized steel SnoBar rails
- MRM mounting brackets - fastened through the panel into wood or steel purlins
- Screw Down 2-Bar Bracket (SC2B) - mounts to the top of the MRM bracket to hold both bars
- #14 woodgrip or self-drilling metal-to-metal fasteners with bonded sealing washers
- Tek screws / retaining hardware to secure bars in the SC2B bracket
- Black polyethylene end caps to seal bar ends
- All hardware required for installation - kit ships complete
Exposed Fastener Panel Compatibility
The double bar screw down SnoBar is compatible with virtually all exposed fastener metal roofing panels - PBR, R-panel, AG panel, 5V Crimp, Tuff Rib, Classic Rib, U-panel and most ribbed through-fastened profiles.
For manufacturer-specific panel profiles and confirmed compatibility, see the full Snow Guard Compatibility by Roof Manufacturer guide.
Installation Overview
The screw down 2 bar SnoBar installs in a straightforward sequence. This overview is intended to help customers understand the general installation process before ordering. Always follow the current manufacturer installation instructions supplied with your order and the project-specific layout provided for your roof.
Product Documentation:
Required Tools
- Drill / impact driver with 3/8" nut driver for #14 screws
- 9/16" hand wrench for SC2B bracket top bolt
- 3/16" Allen bit for set screws
- Tape measure, chalk line, pencil
- Hacksaw and deburring file for field cuts
- Hammer for plastic end caps
Installation Sequence
- Confirm the layout. Use the project-specific spacing layout provided with your order. If no layout was supplied, contact SnoBlox-SnoJax before installation. Every row must land on a structural purlin.
- Locate purlins and mark fastener positions. Most through-fastened roofs have visible panel screws aligned with each purlin - use those as a guide. Mark base locations along the row with chalk line or pencil.
- Set the MRM bracket on the panel flat between minor ribs, centered over the purlin, with bar receivers facing upslope. Drive #14 woodgrip screws for wood purlins or self-drilling metal-to-metal screws for steel purlins through every fastener hole in the base. Seat fasteners so the bonded washer just compresses - do not overdrive.
- Install the Screw Down 2-Bar Bracket (SC2B) on top of each MRM bracket. Tighten the top bolt with a 9/16" hand wrench.
- Repeat across the row at the recommended spacing - typically 12" to 18" on center depending on snow load, panel type, and purlin spacing. Every base must land on a purlin.
- Slide the lower bar through the lower receiver of every SC2B base in the row, then slide the upper bar through the upper receiver. Bars must seat fully and run continuously. Do not extend more than 3" past the last base.
- Secure the bars with the supplied Tek screws and retaining hardware.
- Position SnoBar butt joints correctly. Butt joints must be centered between two bases with no more than a 2" gap at the ends. Short sections must span at least two bases - never clamp a short bar to a single base.
- Install black polyethylene end caps at each bar end. Deburr any field-cut bars before capping.
- Lay out additional rows according to the project-specific spacing layout, always landing each row on a purlin.
Safety: All workers must be harnessed and anchored according to OSHA fall protection guidelines during installation. The SnoBar Screw Down system is not a fall protection tie-off point and must never be used as one.
Design Conditions
- Load path: All loads are transferred through the panel into the purlins. Proper panel attachment and adequate purlin capacity are required. New and existing structures must be evaluated to confirm they can carry retained snow loads.
- Minimum panel: 26-gauge steel over wood purlins or 24-gauge over steel purlins, with panel fasteners correctly installed at the panel manufacturer's recommended spacing. Do not install on panels with loose, pulled, or under-driven fasteners - correct panel attachment first.
- Base spacing: Typically 12" to 18" on center, varies by snow load, panel type, and purlin spacing. Bases may only be placed where they can be fastened through the panel into a purlin.
- Eave overhang: Where there is an overhang at the eave, confirm the overhang can hold the retained snow load - otherwise place the first row at the bearing wall or first purlin.
- Isolated areas: Not recommended for doorways, vents, or partial roof sections. Call for special design considerations.
- Coverage: No snow retention system retains 100% of snow and ice. The system is designed to mitigate the dangers of sliding snow and ice.
Need help sizing your system?
Every project is different. Panel length, roof pitch, purlin spacing, and ground snow load all change how many 6-foot double bar kits you need and how rows should be spaced.
Technical Specifications
- Bar Profile: 1" square tube
- Bar Material: 16-gauge galvanized steel
- Bar Coating: Gator Shield with 50% additional zinc
- Bar Length: 6 feet per rail
- Configuration: Double bar / 2-bar
- Mounting: MRM bracket + SC2B top bracket
- Bracket Material: Mill aluminum, non-corroding
- Fasteners: #14 woodgrip or self-drilling metal-to-metal with bonded sealing washers
- System Type: Mechanically fastened screw-down snow rail
- Panel Compatibility: Exposed fastener metal roofing
- Minimum Panel: 26 ga over wood / 24 ga over steel
- Base Spacing: Typically 12" to 18" on center
- Finish Options: Mill galvanized; powder coat optional
- Origin: Made in the USA
- Warranty: Lifetime warranty on parts, performance, and finish when installed according to the project-specific layout and current manufacturer installation instructions
The SnoBar Difference
Gator Shield Galvanized Coating
Gator Shield galvanized steel uses 50% more pure Western-grade zinc than standard Flo-Coat galvanizing, producing bars with yield strength of at least 50 ksi and tensile strength of 55 ksi. This heavy galvanized finish helps protect the bars against long-term corrosion when installed as directed.
Structural Attachment, Not Panel-Only
Low-cost snow retention systems screw into panel ribs or use a folded strip of panel steel stitched to the roof. Both methods can fail under load because metal roof panels alone are not intended to carry retained snow. The double bar screw down SnoBar mounts through the panel into the purlin, the correct attachment method on exposed fastener roofs.
Field-Proven Since 1992
SnoBar was the original snow rail system. The screw down configuration has protected exposed fastener metal roofs on commercial, industrial, and agricultural buildings across North America for over 30 years.
Frequently Asked Questions
What is a screw down SnoBar and how is it different from a clamp-on SnoBar?
A screw down SnoBar is a mechanically fastened snow rail designed for exposed fastener metal roofs - panels like PBR, R-panel, AG panel, 5V Crimp, Tuff Rib, and Classic Rib. The MRM mounting bracket fastens through the panel directly into the structural purlin below. A clamp-on SnoBar uses a non-penetrating S-5! style clamp that grips the raised seam of a standing seam metal roof and never penetrates the panel. Screw down panels do not have a raised seam to clamp onto, so the screw down configuration is the correct system for through-fastened roofs.
Do I need a single bar or double bar SnoBar?
Use a double bar SnoBar when expected snow loads are heavier, the roof pitch is steeper, panels are longer, or the building protects high-traffic areas like commercial entrances, parking lots, mechanical equipment, or HVAC units below the roofline. The two-bar configuration roughly doubles the physical barrier presented to sliding snow and distributes load across two bearing points at every bracket. Single bar systems are suitable for lighter snow loads, residential buildings in moderate snow regions, and shorter panel lengths. For a project-specific recommendation, request a free SnoBar layout - we will calculate the correct configuration based on your ground snow load, roof pitch, and panel length.
What metal roof panels does the screw down SnoBar work with?
The screw down SnoBar is compatible with virtually all exposed fastener (through-fastened) metal roofing panels - PBR panel, R-panel, AG panel, 5V Crimp, Tuff Rib, Classic Rib, U-panel, Master Rib, Multi-Rib, and most other ribbed through-fastened profiles. The MRM bracket sits on the flat between the major ribs and fastens through the panel into a wood or steel purlin. It is not used on standing seam metal roofs, exposed fastener corrugated panels with insufficient flat area, or shingle and tile roofs.
Do I need to fasten into a purlin or is the panel enough?
Every screw down SnoBar bracket must fasten through the panel and into a structural purlin. Metal roof panels alone are not engineered to carry retained snow loads - all loads must transfer into the purlin and from the purlin into the structure. Most through-fastened roofs have visible panel screws aligned with each purlin, which makes purlin location easy to confirm. If you cannot locate a purlin where a bracket needs to land, contact us before installing - the layout may need adjustment, or the building may need additional blocking.
How far apart should the brackets be spaced?
Bracket spacing is typically 12 to 18 inches on center but varies by ground snow load, roof pitch, panel type, and purlin spacing. The exact spacing for your project comes from the project-specific layout we provide free with every order. Heavier snow loads, steeper pitches, and longer panel lengths require closer bracket spacing. Bases must always land directly over a structural purlin - never extend the layout into a span where there is no purlin to fasten into.
Can I install snow guards only over the front entrance or above a doorway?
No. Installing snow guards in isolated patches over doorways, walkways, vents, or partial roof sections is unsafe and frequently makes the slide hazard worse. Snow above an isolated bar run still slides, ramps over the barrier in a single mass, and releases as one large block that can injure people, damage gutters, and crush whatever is below. Effective snow retention requires continuous rows across the entire roof plane from eave to ridge. For partial-area applications, contact us for special design considerations before ordering.
What is the minimum panel gauge for the screw down SnoBar?
Minimum panel is 26-gauge steel over wood purlins or 24-gauge over steel purlins, with panel fasteners correctly installed at the panel manufacturer's recommended spacing. Lighter-gauge panels do not provide enough mechanical strength around the bracket fastener to develop the load. Panels with loose, pulled, or under-driven fasteners must be corrected before SnoBar installation - the system is only as strong as the panel attachment underneath it.
How many 6-foot double bar SnoBar kits do I need?
Quantity depends on roof width, roof slope length, ground snow load, and roof pitch. As a rough starting point: measure the eave-to-ridge slope length and the eave width, divide the slope length by the row spacing in your project layout to get the number of rows, then multiply by the eave width and divide by 6 feet to get the number of kits. Because the calculation is project-specific, the most reliable way to get an accurate quantity is to request a free SnoBar layout - we will return exact kit counts and bracket locations sized to your roof.
Will the screw down SnoBar leak?
The screw down SnoBar uses #14 fasteners with bonded sealing washers identical to the OEM panel fasteners. When fasteners are seated correctly - so the bonded washer just compresses without being crushed or under-driven - the system is sealed at the same standard as the rest of the panel. Most leaks on through-fastened metal roofs come from over-driven, under-driven, or aged panel fasteners; the SnoBar fasteners are the same technology and have the same expected service life as the panel itself. For added protection, some installers apply a small bead of butyl sealant under the bracket base before fastening, especially on low-slope roofs.
Is the SnoBar made in the USA?
Yes. SnoBar bars and brackets are manufactured in the USA by SnoBlox-SnoJax, the original developer of the SnoBar snow retention system. The product has been engineered, tested, and produced domestically for over 30 years.
Can I use the SnoBar as a fall protection tie-off?
No. The SnoBar Screw Down system is engineered for snow retention only and is not rated, tested, or certified as a fall protection anchor. It must never be used as a tie-off point under any circumstance. Workers installing the system must use OSHA-compliant fall protection - a separately rated roof anchor, full-body harness, energy-absorbing lanyard or self-retracting lifeline, and lifeline as required.
What warranty comes with the screw down SnoBar?
The SnoBar carries a lifetime warranty on parts, performance, and finish when installed according to the project-specific layout and the current manufacturer installation instructions. The warranty requires that the system be installed across the full roof plane (not in isolated patches), that bases land on structural purlins, and that recommended bracket spacing is followed.
Order Your Double Bar Screw Down SnoBar System
Get the right snow retention system the first time. Provide your panel profile, panel length, roof pitch, and location - we will provide a project-specific layout recommendation including quantity and row spacing for your project.
Request a free SnoBar project quote →
Same or next business day processing on in-stock kits. For submittal packages and commercial bulk pricing, contact the manufacturer directly.
