Scratchbuilding a scrap metal container, size needed ?

[0121modeller]

I'm scratchbuiding a couple of these for my scrapyard project.

,I forgot to measure when taking photo! , I'm guessing they're 7ft x 15ft,  Does anyone know for certain what size these containers are ?

 

Thanks in advance.

 

EDIT , I now have dimensions of this, 7'11" wide x 19'9" , heights can vary from 6'6" to 8'3 approx.