Black spider identification
This is very likely an araneid (or Orb-weaver spider) in the family Araneidae. 

Without further evidence/details, it's hard to narrow down to a species. 

One possibility is Larinioides sclopetarius (the bridge spider or gray cross spider). 

 

 Source: Ed Nieuwenhuys 

 

 Source: Eurospiders.com 


Description: 


  Prosoma grey to grey-brown. Opisthosoma grey to grey-brown, dorsally with pronounced, white margined pattern. [Source: University of Bern]



See University of Bern for detailed drawings of anatomical structures. 

Size: females = 10-14 mm ; males = 8-9 mm. 
Web: orb webs can have diameters of up to 70 cm.
Ecology: often lives on briges or near water; often found on steel structures.
Range: holoarctic including Ottawa, Canada






What it's NOT

Although visually similar, this is not 
Nuctenea umbratica (walnut orb-weaver)



 Source 


This species is confined to Europe, Asia and Africa. 


The specimen is also unlikely Larinioides ixobolus, which generally has a black outline (vs white) on their backs And is constrained to Europe/Asia:



 Source