You'll find lots of references to paintability in reference to structural steel and other materials on the net. In your context I think it has to do with being able to get at the surfaces to be painted (the spaces between elements should not be too tight).

Here's a definition of paintability:

"3. Paintability
Paintability is assessed by these criteria: painted surface finish, paint adherence, corrosion resistance after painting, ease of application, and **expenses incurred in painting**." (see first URL below)

If expense is one of the criteria of paintability, then a minimum distance ratio between elements would certainly make sense. The ratio might be distance>height/5, but I haven't found anything on that.

ITF might be the International Transport Federation (unless they are constructing a tennis court?), which also has a land transport workers section. It might make sense that they would establish minimum requirements for "paintability" of construction materials, including a distance ratio--but I have not managed to find more info in this.


http://www.nkk.co.jp/en/steel/kaigai/tcs/products/main.html

http://www.precisionsteel.com/intro2.cfm?Properties=True&Pro...

http://www.damonco.thomasregister.com/olc/damonco/matdesc.ht...