Looking up towards the ceiling of Hangar 1 at Dunnville Airport near Dunnville, Ontario, Canada.   The steel columns and trusses are clearly visible.   The classic construction method of British Commonwealth Air Training Plan "temporary" buildings, a wooden frame covered by diagonal planking, and covered by wooden shingles was used at Dunnville.   From the interior the wooden frame and planking is clearly seen.   The large window opening is covered the metal siding at to the exterior of the building sometime after the war.
<a href="//commons.wikimedia.org/wiki/User:SteveTheAirman" title="User:SteveTheAirman">J. S. (Steve) Bond</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>