File talk:Common leakage sites classified in 4 categories.jpg

This drawing serves as complimentary to the article "building airtightness", and is necessary for the reader to understand the most common leakage sites described in the text. No free equivalent is available, or could be created, that would serve the same encyclopedic purpose.M.Kapsalaki (talk) 16:26, 20 February 2014 (UTC)

See for example WP:NFC#UUI §4. Easily replaceable. --Stefan2 (talk) 16:31, 20 February 2014 (UTC)