This time, I tried to attach a fireplace hood (400 lbs) to the existing wood joist. Using DF #2, I noticed the wood joist could not even hold its own existing loads. But the contractor argued that nobody use DF #2 50 years ago and the joist without any knots should be classified as DF #1 and better.
My question are how to justify the lumber grade 50 years ago and what kind of equivalent values we can use for today's calculations. I like to hear your thoughts.
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