Deck Beam Spans and Joist Cantilevers

Рет қаралды 75,722

Күн бұрын

Пікірлер: 53

@MrDougfunny7 Жыл бұрын

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!

@GlennMathewson Жыл бұрын

You’re welcome! I have a comprehensive series of On-Demand Courses that cover (in depth) all the latest IRC codes for decks. I send a free copy of my ICC deck code book with every enrollment. DeckCodes.com for details.

@MrDougfunny7 Жыл бұрын

@@GlennMathewson yes I may take you up on that offer in the near future. Thanks!

@RayBelizean Ай бұрын

I'm a technical writer and software engineer with a passion for deck building and architecture. This video helped me "somewhat" understand these building codes. Thank you. But it is my observation that the building code documentations are intentionally written in an overly complicated manner. The solution to all these construction methodologies, are super simple, yet written in an over-complicated language, intentionally designed for the average Joe, to have to pick up the phone and call an engineer or an inspector, to make sure that he is within the boundaries of the code. The building codes are superbly important, but more so important for the average Joe to easily understand and build.

@GlennMathewson Ай бұрын

Did you notice at the end of the video I explain how I proposed a change to make the table easier to deal with joist cantilevers. Yes, I know exactly what the IRC is for, as I am a 20 year professional in codes and a historian. But if you think you there is an easier way to present this pre-engineered information than what I showed at the end which is now in the 2024 edition, then you have my full encouragement to create it, propose it and go to the hearings like I did to see it through and into the code. Proposals for the 2027 IRC opened for submission on Oct 10 and closed on Jan 10. Get to work and put your opinions about how to make this easier into the mix with the other people getting it done. Go to CDPAccess.com and make a free account and submit a better span table. I’ve got about 20 proposals I’ll be submitting and they are all about making the code easier to understand and more consistent for everyone to interpret the same. Boom! 😎😀

@GlennMathewson Ай бұрын

**edit. “Will close” on Jan 10. You told me you don’t like what I created and it’s too complicated. Time to put action behind that critique, my dude and contribute your technical writing skills alongside the rest of us. Here is your “formal” invitation. Email me at glenn at BuildingCodeCollege.com and I will volunteer my personal time to help show you how to put your voice into this. It costs nothing but your time and give a damn. And it looks like you have a give a damn already, so now make the time. And not to sound rude, but if you won’t make the time, be thankful to those of us that do and understand we did our best to create a useful code. ❤🇺🇸😊

@JaykUS354 9 ай бұрын

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

@UneducatedGeologist 2 ай бұрын

Part time deck builder. Great informative video!

@markschwartz830 2 жыл бұрын

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

@77dongle 10 ай бұрын

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"?

@angrykatrants Жыл бұрын

Loved this! Thank you!

@donaldsmith3787 14 күн бұрын

Glenn Mathewson I'd like to pick your mind about an issue I'm having with sizing a deck beam.

@donaldsmith3787 14 күн бұрын

How do you calculate the beam sizing and support post spacing when you have multiple beams supporting a deck? For instance, 20x27 deck. 27 ft side ledgered to the house, beam at 10 ft from house, beam at the end (20ft from the house.)

@donaldsmith3787 14 күн бұрын

The chart seems to apply to the outermost beam. 10 ft span, no cantilever. I understand the new calculation to find the "effective span."

@donaldsmith3787 14 күн бұрын

But does that chart apply to the middle beam which is supporting two spans? One to the ledger and one to the outer beam. Am I way off base here?

@garyenwards1608 Ай бұрын

The foundation columns for a 12x16 cabin are already installed. I've decided to go 16x24 instead. We went 10x14 for the columns factoring a cantilever of 1 foot on either side. What would you recommend for floor joist to attempt a 3 foot cantilever? I was thinking 2x8 12"OC or 2x10 12"OC or 16"OC

@jandras1 5 ай бұрын

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?

@jeredmattson9 9 ай бұрын

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

@waltermortimer6205 9 ай бұрын

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?

@GlennMathewson 9 ай бұрын

Yes, a beam sized under the IRC table can cantilever one fourth the adjacent beam span.

@billj5645 Ай бұрын

They are trying to make the load calculation easier for someone who doesn't want to get too far into structural engineering and load calculation using structural analyisis per statics. I would think it would be more direct to go the other way and base the table on a simple span beam without cantilever then use factors larger than 1 multiplied by the span for joists with cantilevers. However if someone just uses the table without understanding the modification factors the table as shown is safer. The addition of joist span plus cantilever at the top seems an easier way to improve accuracy of the table without making it too complex.

@awood186 9 ай бұрын

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

@GlennMathewson 9 ай бұрын

The post size doesn’t really matter much in this discussion. it’s about the connection.

@neiloneill9208 Жыл бұрын

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.

@GlennMathewson Жыл бұрын

Honestly not sure if I am picturing this correctly. The backspan length needs to be one single member, the same as the cantilevered one. If it is continuous over the mid span beam, "technically" that mid span beam is now also likely holding down the joist. So that puts all the stress on the wood fibers supporting the cantilever in the area between the midspan beam and cantilever supporting beam. So in that case, yes, the midspan beam would cause you to measure 'backspan" to it. Now... with all that said, personally speaking, I'm not really worried about that. But that's an informal final opinion from a code guy trying to understanding engineering principles.

@bethw5998 5 ай бұрын

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

@baubljos103 8 күн бұрын

Great Glenn thx, just what I'm looking for. However, would you consider slowing down your speech ? Anyone who wants to listen will, so you don't need to rush the explanation.

@strokerace4765 Жыл бұрын

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

@AllFallBeforeMe Жыл бұрын

Use the table in the IRC before you build sonething you might have to rebuild.

@chodge8366 Жыл бұрын

I would rather overbuild than under build. especially raised 6-8’ off the ground with 10 people on it. stick with 10’s and 12’s

@MrDougfunny7 Жыл бұрын

What joist spacing? I use 2x8 for 12'. It's fine.

@garyenwards1608 Ай бұрын

@chrislcaggie141 Ай бұрын

Not all codes are for the better and easy s9me are helpful

@rufushughes5602 10 ай бұрын

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.

@GlennMathewson 10 ай бұрын

You know I’m right here, right? You don’t have to refer to me in third person. I’m a real live human and all…. Thanks for the feedback. This video was an experiment.

@christopherstafford227 9 ай бұрын

I’m an average person and followed it just fine. Besides, it’s a KZbin video and you can adjust playback speeds in the settings, or watch it again.

@bethw5998 5 ай бұрын

@@GlennMathewson it's a great vid. pausing video is a helpful tool. some people are just big complainers

@larrylilly2714 5 ай бұрын

@@christopherstafford227

@MichaelHyde 3 ай бұрын

Please keep up these excellent videos. They are very very helpful. Thank you!

@AllFallBeforeMe Жыл бұрын

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.

@AllFallBeforeMe Жыл бұрын

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

@MrDougfunny7 Жыл бұрын

skill issue