Snow Guards
A snow guard is a device or system that increases friction between roof and snow, retaining a snow pack on a roof, so that it evacuates in a predictable and controlled fashion (evaporation and thaw) rather than by a sudden and dangerous rooftop avalanche
When snow avalanches off of a rooftop, it can damage anything in its path. This sudden release of snow can be dramatic—dumping tons of snow all at once. This can have dramatic results -damaging gutters, vehicles, and landscape. Once piled up below, that same snowbank can go on to cause additional troubles, like structural or cosmetic damage to the building walls. In any event, the removal of avalanched snow from walkways, entries and parking areas is a constant maintenance nuisance.
Falling snow forms a temperature-sensitive bond to the surface of a metal roof. As that roof is warmed, (through an invisible spectrum of sunlight or from building heat loss), the bond with the snow is broken and a thin film of meltwater lubricates the roof. This causes a sudden release from a rooftop that can dump many tons of snow below the eaves in a matter of seconds, endangering building elements, landscape, vehicles and pedestrians.
Snow guards should always be placed at the lower half of the roof near the eave. It is recommended to place snow guards no further back than 12” from the eave of the roof; in some cases, multiple rows of snow guards will be needed which is why you should always talk to someone who specializes in snow guards.
The cost of a snow guard depends on the style of snow you choose whether you have a standing seam roof or an exposed fastened (screw down) roof. If you have a standing seam roof the best option is to choose a snow guard that clamps onto the seam which avoids putting holes into your brand-new roof. If you have an exposed fastened roof (screw down) you will have to choose a snow guard that is secured to the substructure under your roof. On average, a properly tested and engineered snow guard system will start around $12.00 a foot Canadian.
Adhesive snow guards rely on an adhesive to secure the snow guard to the roof. The problem with these is that they can only be installed during warmer months, the adhesive must have proper conditions for the adhesive to cure and usually require multiple call backs to replace them. Adhesives will break down due to UV exposure and will weaken over time resulting in failure. Further, the adhesive type of snow guards looks clear at first, but over time they tend to yellow due to chemical breakdown in the product.
Yes. For years there has been a practice of simply installing some type of snow guard on a roof and hope for the best which can result in snow guard failure and damage to the roof. Each roof or project can have different design elements that will affect the proper design of a snow guard. For example, there is an upper roof that sheds snow down to a lower roof that can increase the snow load on the lower roof. Valleys created by dormers can introduce a funnelling effect which in certain cases will also increase now loads. It also depends on where you live, some areas of Canada have higher snow loads than others which MUST be taken into consideration.
Placing snow guards over an entranceway can be done but it is not advised. It is very difficult to predict how snow will break and slide down the roof. Snow will not break in a straight line, it tends to break and pile in a wedge shape pattern which can overload the snow guard or miss it entirely. Another way to visualize it; you are trying to manage 100% of the snow load by only using 40% of a snow guard.
Solar
The key to frequency and spacing of attachment points for PV is to distribute loads to the metal standing seam panels in a manner that is consistent with the intended distribution of loads from the roof panels into the building structure.
NOTE: The following suggestions assume that determination has been made that the roof to which the S-5! clamps will be attached is structurally adequate. Any loads imposed on the S-5! clamps will be transferred to the panels. Panel seams must have sufficient flexural strength to carry these loads. Panels must also be adequately attached to the building structure, and the structure must be sufficient to carry these loads. The makers of S-5! clamps make no representations with respect to these variables. It is the responsibility of the user to verify this information or seek assistance from a qualified design professional, if necessary.
With very few exceptions, the attachment of a single S-5! clamp (even the “Mini”) to the seam will be stronger than a single point of attachment of the seam to the building structure. Hence the “weak link” is not the S-5! clamp, but the attachment clips that hold the metal panels to the building structure, or the beam strength of the roof panel seam, itself.
The most conservative approach to the spacing/frequency of PV attachment to the roof is to determine the spacing/frequency of the roof’s attachment to the building structure; then duplicate it at minimum.
Determining panel attachment spacing in one axis is very simple: Standing seam panels’ attachment will be made using concealed hold-down clips within the seam area of the panel. So, in that axis, the clip spacing is the same as the seam spacing. The location of the clips along the seam (in the other axis) can be determined by
- a) consultation with the roof system manufacturer or installer,
- b) checking from the underside or,
- c) close examination from the topside along the seam. There will usually be a slight, but detectable, deformation of the seam at the clip location visible from the roof’s topside. Many standing seam roofing systems are installed on “pre-engineered steel” buildings. The attachment spacing in that industry is typically 5’-0” and is readily apparent by inspecting the structural purlins to which the panel clips are attached from the roof underside (interior of the building).
If the panel clips are spaced, for instance, 5′-0″ on center along the seam, then use the 5′-0″ dimension as a maximum spacing for the S-5! clamps. (S-5! clamps may also be spaced at closer centers, but not wider.) When modules are direct-attached (without racking) in the landscape orientation, this spacing dimension is dictated by the smallest dimension of the PV frame.
Using the roof panel clip spacing as a maximum spacing template for S-5! clamps is a sound practice, whether the PV modules are attached directly to S-5! clamps or brackets, or to a racking system, which is in turn attached to the S-5! attachments (and then panel seams).
To evenly distribute loads, it is also necessary that each seam be involved in the finished assembly. Thus, every time a seam is traversed, it should be attached. Such an attachment scheme should evenly distribute wind loads into the building structure through the panels and their attachment, as was intended in the original roof construction assembly.
Please note these are only suggestions. Wind dynamics are complex, and S-5! advises review by a qualified licensed professional who understands wind effects and metal roof design and construction.
The S-5 PVKIT / S-5! standing seam clamp assembly is a UL2703 listed bonding device. While the listing covers carrying a ground path from PV panel to PV panel, the clamp to the roof panel material is not included in this certification.
On an individual basis, some independent racking companies have worked with certification labs to verify the clamp-to-roof connection and its reliability as a bonding path. For instance, IronRidge has found that S-5! clamps provide a reliable bond path between the clamps and the roofing panels beneath the array. This rating is included in their racking systems UL2703 listing.
Grounding path as concerns module-level-power electronics (MLPE): If the microinverter does not have internal grounding, then it will need to be independently grounded when fixed to the roof. If the microinverter is fixed to the module frame, then it can be grounded via the module frame.
S-5! Clamps
You should always be concerned about metallurgical compatibility. Incompatibility can cause rapid galvanic corrosion and void material warranties. S-5! aluminum clamps are completely compatible with painted or unpainted G-90 galvanized steel, bare or painted Aluminized, Galvalume, Zincalume, ZincalumePlus, Acrylume Galvalume Plus, Galfan, Bonderized and Galvanneal steel. They are also compatible with aluminum (painted, bare, or anodized), titanium-zinc (VM & Rheinzink), and with stainless steel. The brass clamp S-5-B is compatible with everything the aluminum clamp is not (copper and its alloys).
If you have concerns or questions regarding clamp compatibility with your roofing material please reach out to us at sales@skyproducts.ca
We would never promote a product that solves one problem on a metal roof while creating another. The metallic coatings on steel sheet are very thin but very important for corrosion protection of the base steel. They must not be breached. That’s why we created our custom-designed, stainless steel setscrew. We went to great lengths to have these setscrews custom made to our exact specifications before ever taking our products to market. This special screw has a polished rounded end to prevent damage to the protective coatings of steel sheet. But we didn’t stop there.
These round-point setscrews (or oval-shaped point on one end) are shaped to a specific radius and polished to eliminate abrasion to the panel finish when tensioned. But we didn’t stop there either. We have also performed 2000 hour ASTM B-117 Salt Fog testing on our clamps and setscrews, attached to Galvalume® coated steel panels to prove they maintain perfect metals compatibility and cause no mechanical damage to the coating.
Although standard “cup point” setscrews are lower in cost, they should never be used on coated steel (as some of our competitors may claim). The cup point digs through the coating, creating a corrosion site.
In addition, all our related hardware is non-corrosive, 300 series stainless, not plated steel. The unique S-5! round-point setscrews are always furnished with our clamps because they offer a secure mechanical connection while protecting roof warranties.
The answer to this question varies with the load direction, the seam profile, the roof material and the clamp model.
These variables result with a wide range of holding capacities from ±300 lbs (235 kg) to ±4,000 lbs (1800 kg). This is why for critical applications it is important to correctly identify the roof panel, seam type, gauge, etc along with the recommended seam clamp for the specific roof. [ link– Clamp-to-seam tool] When used on some “applied cap” architectural type seam styles, S-5! may yield low load-to-failure results as compared with integrated seam profiles. Always check our load table to verify the correct allowable holding strength on your specific roof type.
We perform hundreds of rigorous tensile load tests parallel and normal to the panel seam on various gauges and profiles, the results are tabulated for your convenience here: Load Test Results.
In the parallel load direction, loads that are introduced into the clamp will transfer to the panel’s seam and accumulate to the point of fixity in tension (or compression). Roof panels must be adequately attached to resist these loads. S-5! clamps have been laboratory-tested on various seam types, profiles, and materials for ultimate failure loads parallel to panel seam (“drag” type loads). The ultimate load-to-failure results vary with individual panel profiles and gauges. Watch this video to understand more about testing and why we test. [insert ways we test video].
In the negative normal load direction, with few exceptions, the attachment of a single S-5! clamp (even the “Mini”) to the seam will be stronger than a single point of attachment of the seam to the building structure. The “weak link” then is not the S-5! clamp, but the attachment clips that hold the metal panels to the building structure, or the beam strength of the roof panel seam, itself. Ultimate loads normal to the panel seam (both positive and negative) are more a function of the panel’s beam strength and the failure strength of the panel’s attachment clips than of the holding strength of the S-5! clamp on the panel seam. These values will also change with various attachment spacing.
ASTM standard E-1514-93 for structural standing seam metal roofing requires that roof panels by design must withstand a minimum 200-pound point load in positive (downward) pressure at the panel’s weakest point (the flat of the panel at midspan). The Army Corps of Engineers Technical Instructions for metal roof design spec (TI 809-29) says that the same value should be 300 pounds.
Almost any structural metal panel system will meet and easily exceed the above specifications. The seam area is also much stronger than the panel flat. S-5 attachments transfer positive loads into the panel seam. HVAC units, for example, are mounted successfully in this fashion on numerous projects, utilizing four, six, or eight clamps (bearing points) for a single unit of considerable weight, by distributing the weight of the unit equally over those bearing points so as to maintain a maximum point load within ASTM or ACOE limitations. The building structure must also be designed to support these loads.
We are a Canadian company! Sky Products has grown to be and remains the number one S-5! distributor in Canada and works with Architectural and Engineering firms, Metal Roof Manufacturers, Contractors and Suppliers to homeowners across Canada to provide the best solution from snow guards to solar panel attachment points.
We offer a range of services such as technical and customer support, engineered stamped drawings, architectural specifications, snow guard layout recommendations, powder coating, Canada wide shipping and the largest stock of S-5! products in Canada.
