I'm a newbie to deck building and am just reading through the code book and a Black and Decker book designing decks. I just came to this exact issue and was puzzled, until I found this video. I guessed it worked as you said, but thanks for confirming it, as I'm hesitant to think I am correct as I have had no formal training. You're awesome dude!

Thanks Glen, I'd love to see this expanded info in the 2024 IRC.

Building a low-level 32’x26’ deck and this helped a ton! Thank you

Such a helpful video! One Question- I need to calculate the "joist span factor" on a 9' wide freestanding deck with only 2 beams, and joists cantilevering 18" beyond beams at both ends. To determine the "actual joist cantilever", do you add both cantilevers together (making it 36") or use 18"?

Thanks for this! Question re "joist BACK span" which is confusing me At 1:05, in the "maximum cantilever" portion of Table R507.6, it refers to "joist back span" in feet, in 2' increments, from 4' up to the number that is just below the max. "allowable joist span." What is a a "joist BACK span?" It's not defined. Is that the actual ledger-to-beam distance for your joists? If so, isn't that what "joist span" already means?

Loved this! Thank you!

would love to find an online calculator that could do this. probably is one somewhere ??

Thanks Glenn, great explanation of the 2021 and the proposed 2024. Makes sense. Question though, using the allowable beam span can the beam also have a cantilever on the beam beyond the post, like 1/4 the beam length?

Is this for 4x4 posts on these beam spans or we talking 6x6 or does it matter?

Glen, I’m currently extending my deck (original 12x12, but 16’ in one side due to stair landing. I’m extending the 16’ side 8 more feet. So I had to extend the current beam which is around 10’ from the house, but then added a second beam supporting the landing and the new extension around 13.5’ from the house, which left me me with a 2’-6” cantilever. Is this cantilever ok? All I see in the tables is “back span” but doesn’t take in consideration if you have a second beam/support. Without taking the second beam in consideration, if I only go with the first back span at 10’, I’m allow 2-6” cantilever correct? Joist are 2x8s and beams are double 2x12s. Hopefully my confusion and question make sense to you. Thanks in advance.

If you play this video at .75 speed, it is more comprehensible.

I have been building 10x12 decks, I use 2x10s, usually have a two foot canterlever, could I get by with using 2x8 joists instead?

No matter what you build always try to keep it simple. Lots of builders and architects are trying to show off their pretty skills and then a bunch of errors are made when their plans are more complicated than they need to be. Same with cars and trucks.

There's no way an average person can keep up and get a good understanding he talks much too fast and move through the lesson too fast.

I have no idea what I'm seeing. I cannot decipher your plans.

You talk too fast. Thanks. Ill check someone else

Geez what did you say ,,,,slow down or get off the coffee

your videos are great. i’m building a 14x20’ deck that cantilevers; my beam needs to be 20’ but i’m confused on the tables, should i just use 4 beams made up of double 2x10 that are all 5’ long to equal the 20’ span? and insight would be appreciated