Bird-friendly glass treatment
What is bird-friendly glass?
Short answer
Glass treated so birds can see it. In practice that means a marker pattern on the outside surface, spaced closely enough that a bird will not try to fly between the markers. The Canadian standard CSA A460 sets out marker size, spacing and how much of a facade to treat.
Birds do not perceive glass. They see reflected sky, trees and open space, and fly into it. Collision estimates for North America run into the hundreds of millions to over a billion birds a year, and most of those collisions happen at low-rise buildings and homes rather than towers.
Bird-friendly glazing solves this with visual markers. The key requirements are consistent across the guidance: the markers must be on the first surface, meaning the exterior face of the glass, because anything behind a reflective outer surface is invisible from the bird's side. And the spacing must be tight. Guidance has moved from the older two-by-four inch rule toward a two-by-two inch approach, and Canada's CSA A460 standard specifies markers of at least 4 mm with spacing no greater than 50 mm.
Different frameworks add their own thresholds. CSA A460 addresses the treated height above grade and the proportion of glazing covered. The Toronto Green Standard sets its own coverage requirement for the lower storeys. American Bird Conservancy publishes a threat factor rating for products, and the LEED bird collision deterrence pilot credit uses a calculated building threat rating plus post-occupancy monitoring.
Retrofit film is how existing buildings comply. It applies to the outside of the glass and, because the markers are small and evenly distributed, occupants inside generally stop noticing the pattern within days.
The requirements that matter
- Markers on the first (exterior) surface of the glazing
- CSA A460: markers at least 4 mm, spaced no more than 50 mm apart
- A defined treated height above grade and above adjacent green roofs
- A minimum proportion of the glazing area covered
- Product threat factor ratings where a rating system is being pursued
Tell us which standard your project is assessed against before we quote, because the spacing and coverage numbers change the material and the price.