How common is it that chimney liners cannot be seen from inside the fireplace using only a flashlight?
“Is there some standard building requirement for the flue and the fireplace that you can’t just look up from the fireplace and see the sky or chimney cap at the top of the chimney?” Flues are allowed to have up to 30 degree offsets. In most cases this will make a direct visual observation of the flue impossible. A video scan would be required to evaluate the flue condition. The height of the chimney flue is not a factor. There is a big difference in what is observed between a visual inspection and a video inspection, even in short flues.
