Alpine’s 5th year of snow guard testing was off to a snowy start, then early “Deepcember” yielded to rain. Still, snow guard performance went from ideal (as reported initially in the testing phase) to excellent at this juncture based on performance during thawing and freezing cycles. Read on for data analysis from multiple snow events, including three storms in three weeks, followed by two back-to-back events that yielded the latest findings.
Snow Retention Findings & Best Practices
After careful data analysis, we’ll share snow retention test findings here to shape future recommendations specific to our products. Please bookmark this blog to help inform your team on best practices as they relate to Alpine SnowGuards’ products paired with multiple roof types.
Snow Retention Testing Goals
Alpine’s goals for testing snow retention systems are two-fold: first, testing is an important factor of our recommended snow guard layouts; secondly, testing will help to determine which products perform best under a set of distinct variables. This knowledge will allow us to expertly advise customers on which systems will perform best for their application.
Importance of Following Manufacturer’s Recommended Layouts
Snow guards are safety devices and it’s important to follow a manufacturer’s recommended layouts to achieve maximum snow guard performance. To emphasize this, there are no reported failures of Alpine SnowGuards’ snow retention systems when they are properly installed. We provide free recommended layouts that benefit all parties involved.
2023-24 Performance Testing
Testing Snow Retention Systems for DaVinci Composite Tiles
Alpine retrofit two roofs with materials provided by composite tile pioneers DaVinci Roofscapes: DaVinci Multi-Width Shake and Single-Width Slate. We’re testing Fusion-Guard on the shake and PD40s on the slate. DaVinci performance test observations and videos for this season can be found here: “Testing Snow Retention Systems for DaVinci Composite Tiles.”
Testing Multiple Roof Types, including synthetic, solar, membrane and metal
SNOW EVENTS: Nov. 9-10
Temperatures are in Degrees Fahrenheit
- Snowfall: 5:30 to 7 a.m. on Nov. 9
- Temperature: Temps rose from 28° to 32° by 12 p.m., Nov. 9 and stayed above freezing until 11 p.m., when temps spiked to about 40°. Some fluctuations throughout morning hours of Nov. 10, but temps rose over 40° and remained there after 7:00 a.m. until full melt occurred by 2 p.m.
- Humidity & Wind: 86%-88% with still wind (<5mph average)
- Total snow accumulation: less than the height of the roof separation joints, or less than 3”
PERFORMANCE: EcoStar & Wire Loops 12:12 Pitch
Snow fell in a consistent blanket and condensed down the roof as melting occurred
As temps rose well above freezing around 11 p.m. on Nov. 9, the snow movement (slumping) became more pronounced and waves formed around the snow guards.
Ideal behavior on this roof pitch: snow guards held the snow back from sliding off freely and allowed it to move down the roof in a very slow, and controlled manner through full melt-out
SNOW EVENTS: Nov. 26 – Dec. 6
- Snowfall: 10 p.m. on Nov. 26 to 7 a.m. on Nov. 27
- Temperature:
- Nov. 27: hovered at 32°-33° and began rising at 9 a.m., hitting a peak of 39° in the afternoon
- Wind: averaging ~10 mph
- Total snow accumulation: 3” on the roof
- Snowfall: 3:30 p.m. on Nov. 28 to 3:30 a.m. on Nov. 29
- Temperature:
- Nov. 28: 28°
- Nov. 29: 28° an overnight low of 21°
- Nov. 30: 32° at 10 a.m., 41° at 3 p.m. and an evening low of 30° saw some re-freezing occur before temps rose quickly over freezing
- Dec. 1-6: rose quickly above freezing by 5:30 p.m., reached a high of 45 by 2 a.m. on Dec. 2, at or above freezing until 2 p.m. Dec. 4, and below freezing through Dec. 6
- Wind: averaging 5-8 mph caused drifting snow on 12:12 PITCH and reduce accumulation on 7:12 PITCH
- Total Snow Accumulation: 3” on the roof; little appreciable movement of the snow other than densification with Nov. 29th’s overnight low; additional snowfall of approximately 1-1/2” fell the evening of Dec. 3 into the overnight hours
PERFORMANCE: EcoStar & Wire Loops 12:12 Pitch
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- Ideal behavior was observed throughout this time period with all snow basically remaining on the roof through full melt-out
- Slumping and movement occurred with no larger releases
SNOW EVENTS: Dec. 10-12
- Snowfall: Rain began Dec. 10 around 6 p.m. and turned to accumulating snow at 11:45 p.m. when the air temperature on our weather station read 33°. Snow continued off and on throughout Dec.. 11 and ended about 6 a.m. Dec. 12.
- Temperature: Temps hovered around the 32° freezing point until about 5 p.m. on Dec. 11, before dropping to a low of 18° at 5:15 a.m. on Dec. 12, and rose to a high of 36° during the day.
- Total Snow Accumulation: Approximately 5-6″, Dec. 10-11.
SNOW EVENTS: Dec. 13-14
- Snowfall: Rain fell before turning into slushy ice/snow and snow accumulations.
- Temperature: Temps hit a low of 15° at 8:15 a.m. on Dec. 14, a high of 30° at 3 p.m. and an overnight low of 16°. Temps rose quickly heading into Dec. 15 with an afternoon high of 46°, stayed in the 30’s throughout the afternoon and rose back into the 40’s on Dec. 16.
- Total Snow Accumulation: Additional 1-2″, Dec. 13-14.
PERFORMANCE: EcoStar & Wire Loop HDs 12:12 Pitch
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- Dec. 10-12 snow events captured above – rain turning into slushy ice/snow and snow accumulations – were an optimal cycle for the Wire Loops in terms of performance
- Rainfall turning to ice on the shingle prior to snow accumulation provided a textured base of friction to help hold the snow on the roof
- As temps continued to drop below freezing on Dec. 12, snow solidified around the Wire Loops
- As temps rose above freezing Dec. 15-16, snow slowly melted away from and slumped around the snow guards
- Any amount of falling below the snow guards were small, controlled pieces.
- Performance: Excellent
PERFORMANCE: Metal Exposed Fastener with Snow Bird 12:12 Pitch
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- Snow fell in an even blanket initially, but slumped downslope during the course of the first snowfall event due to the wet nature of the snow and the steep slope.
- Snow Birds held the snow on the roof while some snow below the guards fell off
- Remainder of snow stayed in place until full melt out occurred days later
- Performance may be enhanced over a new metal corrugated roof due to the age of the roof impacting the surface slickness
- Performance: Excellent
PERFORMANCE: Solar Array with Solar Snow Dogs and Solar SnowMax Universal 8 1/2:12 pitch, (35°)
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- As snow fell, it slumped down the glass panel surface
- Accumulations built against the Snow Dogs and bar system, but little to no snow fell from the panels through full melt out
- Performance: Excellent
PERFORMANCE: Membrane with SnowMax Membrane 1.5, 8 1/2:12 pitch, (35°)
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- Snow fell in an even blanket and was retained through full melt out with no movement
- Performance: Excellent
SNOW EVENTS: Jan. 6-24
PERFORMANCE: EcoStar & Wire Loop HDs 12:12 PITCH
- Jan. 6 storm – Snow built up Jan. 6-7 and then on Jan. 8 at midday (1 p.m.) a portion of the snow released from the roof on the left side, then about 10 minutes later most of the remainder released from the right side. Temperatures during snow fall were low to mid 20’s thru to release
- Jan. 9 snow began at 6 p.m. and fell through 2 a.m. quickly accumulating 6-7”. Temperatures started in the mid to high 20’s and then continued above freezing at midnight and into the mid-40’s by 2 p.m. Snow accumulated on the roof and began slumping toward the bottom; falling off in small pieces but no snow slides occurred.
- Overnight Jan. 15-16 a thin layer of frost formed on the roof preceding a relatively quick accumulation of 4-5” of snow by 6 p.m. Temperatures dropped to single digits overnight and rose to a high of 18° during the snow fall event.
- Slumping became noticeable about 6 p.m. on Jan. 17 and progressed overnight
- Additional dusting of snow occurred overnight Jan. 18-19.
- Snow continued to compact and slump with another dusting on Jan. 21.
- Temperatures during this stretch reached a high of 21° and a low -3°.
- On Jan. 22 temperatures rose quickly to 32° by 3:30 p.m.. and stayed there through Jan. 23 at 3:30 p.m. when they began to decline. During that time considerable snow slumping and melt occurred. Re-freezing of the pack occurred around 6 p.m. Jan. 23.
- Some additional snow accumulation occurred Jan. 24 before mild weather just above freezing arrived all day Jan. 25 and remained throughout the remainder of snow melt by Jan. 27, 5 p.m.
- Performance: Mixed. Snow slides occurred during the early Jan. storm related to snow drifting at the peak. The snow pack didn’t have enough internal strength to support the heavier weight load above. During the snow events in mid-January, the wire loop snow guards performed ideally.
PERFORMANCE: Solar Array with Solar Snow Dogs and Solar SnowMax Universal 8 1/2:12 pitch, (35°)
- 6” or so of dry fluffy snow built up on Jan. 7. Another dusting occurred during the evening of the 9th as temperatures climbed into the 30’s and hit a high of 40° during the early morning hours of Jan. 10. Snow shed off the array in one mass slide with a small amount retained by the bars.
- Several snow dustings and melts occurred without incident. On Jan. 16-17 several inches of snow built up with temperatures in the mid to high teens. During the afternoon on Jan. 17 snow broke free from the top panel on the right side only and slid over the snow retained by the Snow Dogs and then pushed some of the snow off the lower panel off as well. Several more storms occurred with additional accumulation and melt until full melt out on Jan. 26. Snow on the left side never released.
- Performance: Mixed. Jan. 7-10 – snow accumulated on the array with temps in the 20’s, stayed a few days until temps rose to a high of 40° the morning of Jan. 10 where the water content of the snow made it weak enough to break and slide. It appears to happen through buckling action above the Snow Dog.
- Multiple smaller events with perfect snow holding.
- Jan. 17 – another snow slide occurred on the right side only. We believe this is related to wind scouring snow off the left side panels or they may have slid as well. The right side panels released due to apparent buckling action above the Snow Dog that starts the slide.
- Performance: Mixed, probably related to wind scouring of the left side and unequal loading between the left and right sides of the array.
PERFORMANCE: Membrane with SnowMax Membrane 1.5, 8 1/2:12 pitch, (35°)
- Snow accumulated and melted. No slides occurred.
- Performance: Ideal
SNOW EVENT: February 13-15
- Snowfall: Approximately 4”
- Temperature range, avg: 11°-35°, 24°
- Humidity range, avg: 54%-88%, 72%
- Wind, range, avg: 0-16 mph, 6.5 mph
- Total snow accumulation: ~4”
- Notes: Frost formed and then snow fell the early morning hours of February 14th. Fully melted on February 15th with temperatures peaking at 28 degrees.
SNOW EVENT: February 15-16
- Snowfall: ~4”
- Temperature: 3°-27°, 18°
- Humidity: 43%-87%, 68%
- Wind: 0-12 mph, average of 40
- Total snow accumulation: ~4”
- Notes: Snow began around 8 PM on 2/15 and continued through the night to 7 AM on 2/16
SNOW EVENT: February 18
- Snowfall: ~1”
- Temperature: 13°-28°, 21°
- Humidity: 59%-81%, 69%
- Wind: 0-9 mph, 5 mph
- Total snow accumulation: ~1”
SNOW EVENT: February 26
- Snowfall: ~1”
- Temperature: 25°-41°, 32°
- Humidity: 56%-88%, 78%
- Wind: 0-7 mph, 2.5 mph
- Total snow accumulation: ~1”
Performance: EcoStar & Wire Loop HDs 12:12 PITCH
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- SNOW EVENT: 2/13-2/15, 2024: Snow accumulated behind and was retained by the Wire Loop HD snow guards.
- SNOW EVENT: 2/16, 2024: A snow slide occurred mid-day beginning at the ridge and removing the snow below. There was a significant drift at the ridge when this occurred. No frost accumulation was witnessed like it was in the hours prior to the 2/13 storm.
- SNOW EVENT: 2/18-2/19, 2024: snow accumulated and melted off in small amounts with no slides
- Performance: Mixed
PERFORMANCE: Solar Array with Solar Snow Dogs and Solar SnowMax Universal 8 1/2:12 pitch, (35°)
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- SNOW EVENT: 2/15-2/21, 2024: Snow accumulated on the panels with and without snow guards. There was somewhat more snow movement on the panel(s) without snow guards on the bottom panel. Some icicle formation at the bottom of the panels behind the SSM-Universal snow guard. Upslope Snow Dogs performed ideally.
- Performance: Excellent
PERFORMANCE: Membrane with SnowMax Membrane 1.5, 8 1/2:12 pitch, (35°)
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- SNOW EVENT: 2/15-2/21, 2024 – snow accumulated on the roof and was retained by the SnowMax-Membrane system through full melt-out.
- Performance: Ideal
PERFORMANCE: Metal Exposed Fastener with Snow Bird 12:12 PITCH
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- Performance: Corrugated Metal – Snow Bird – 12/12 pitch
- SNOW EVENTS: 2/13-2/26, 2024: Snow accumulated behind the Snow Birds and was held in place. Snow slumped against the Snow Bird and the density of the snow pack appeared to change over time, but the snow guards held the pack steadfastly through melt-out.
- Performance: Ideal
Extensive Data Collection
Alpine collects extensive data 24-7 all across our 80 psf ground snow load performance facility in Morrisville, VT with a Weather Davis Station, 16 cameras on 12 roof types, and also conducts structural tests in-house.
For more information, check out:
“Alpine SnowGuards Installs New DaVinci Shake and Slate for 5th Year of Performance Testing”
“Testing Snow Retention Systems for DaVinci Composite Tiles”
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Alpine SnowGuards designs, engineers, and manufactures snow management systems from our facilities in Morrisville, VT. We work closely with leading roofing contractors, engineering firms, developers, and roofing manufacturers to ensure we deliver quality products that do what we say they’ll do. Alpine SnowGuards can help a building qualify for LEED® credits.