Snow Guard / Retention Row Layout

Vector force = snow load x sin(roof angle), times the rafter length above the row; guards per foot = force x safety factor / the guard's TESTED capacity. 40 psf on a 4:12 with a 30-ft rafter pushes 379 lb per foot of eave - 61 guards at 7.9 in on center over a 40-ft eave with 500-lb clamps at a 2.0 factor. No capacity is shipped: it must come from the manufacturer's test data for your exact panel and seam.

vector force (psf) = roof snow load x sin(roof angle); force per ft of eave = vector force x rafter (slope) length; guards per ft = force x safety factor / tested guard capacity; spacing = 12 / guards per ft.

Manufacturer snow-retention design method (roof snow x sine of the roof angle, times rafter length and tributary width), by name - not a code section.

The method is published across independent snow-retention design references and manufacturer design guides.

Estimate. AHJ and licensed professional govern.

Field names used by the API: roof_snow_psf, pitch_rise_per_12, rafter_length_ft, eave_length_ft, guard_capacity_lb, safety_factor, rows, slope_deg, vector_psf, force_plf, guards_per_ft, spacing_in, guards_per_row, guards_total

• Vector force snow load x sin(roof angle); the cosine component is carried by the roof, not the guardsmanufacturer snow-retention method
• Capacity is an input no holding capacity shipped; use tested data for the exact panel, seam, and attachmentmanufacturer test data
• Slope length, stated rafter length used per the manufacturer method, conservative vs the horizontal projection by 1/cos(theta)stated conservatism