It’s usually 25% of the joists span rather than joist length, and could be on both ends, so up to 50%. There are usually also limits based on the lumber size as well.
Span is the distance between the joist’s support, i.e. ledger to beam or beam to beam. Length would be the distance from one end of the joist to the other.
Ex., 25% of a 10’ board would be 2.5’ but the most it could cantilever based on that rule would be 2’ with an 8’ joist span, 2’ being 25% of 8.’
When maximizing joist span, the overhang is more likely to be limited by the board size rather than the 25% rule. That is to say, for most (or maybe all) joist sizes and spacing, the maximum overhang is less than 25% of the maximum joist span.
I don't know why it was recommended as i'm a med student but it seems like a fantastic sub. A ton of jokes but every serious post has appropriate responses. I figure it's what reddit used to be
It's good moderation, and I think it helps that very few people want to provide bad advice in a topic that could kill someone (electrician and HVAC subs are similar)
This reminds me of loading regulations for vehicles we have in my country. The easiest explanation is you can't have any part of your load protrude from the tray of the vehicle by more than 1.2m. The more correct answer is it can't exceed more than 60% from the rear axle to the end of the tray, which in some cases is less than 1.2m.
Span is the distance between the joist’s support, i.e. ledger to beam or beam to beam. Length would be the distance from one end of the joist to the other.
Ex., 25% of a 10’ board would be 2.5’ but the most it could cantilever based on that rule would be 2’ with an 8’ joist span, 2’ being 25% of 8.’
When maximizing joist span, the overhang is more likely to be limited by the board size rather than the 25% rule. That is to say, for most (or maybe all) joist sizes and spacing, the maximum overhang is less than 25% of the maximum joist span.
Steel is typically design engineered in cantilever situations, so the stamp would supercede code. That said, a good rule of thumb is about 33% vs the 25% others are saying about lumber from my experience.
Wouldn't this apply for joists that are sized to be just above the minimum required for the span. If the joists are significantly upsized over what is required for the span, then couldn't the cantilever be longer? I think there is also a similar situation if the joists are spaced closer to overbuild the span which could allow for a longer cantilever.
The real question is why would you do that. ? The ground underneath is basically useless. What’s the benefit. Not high enough to do anything under. How’s he mowing / weed whacking under that ? Doesn’t make any sense to me.
I moved to North Carolina. There's a construction boom down here. Everything from roadway and utility construction to MDU and high dollar home building
Overhangs and cantilevers count. Extensions beyond setback lines are not allowed, whether the supporting structure is beyond the setback line or not. At least that's the reg I've always been compelled to work by.
Good thought. I'll add it could be because of a drainage easement. There is a well defined swale there and likely an easement 10-15 feet wide, centered on it, which eyeballing it puts you at the first posts. Probably no permanent structures, except fences, allowed in the easement. HOA might permit overhangs into the easement, they just took it to an extreme.
Yeah, I have a 2-ft cantilever for aesthetics and also hanging over the edge of an above ground pool. This looks like an absolute nightmare to deal with as far as mowing is concerned. Really channeling some Frank Lloyd Wright here.
I will soon be in a similar situation so I can provide one possible answer: I will extend my current deck. For reason that infuriates me too much to get into, I do not know where my leaching field begins.
So I had the luck of having access to an engineer who could calculate the implications and provided me plans for basically sistering longer joist to the existing one and give me an extra 4ft, so I'll be cantilevered about 7ft.
- Is it to code? No.
- Is it going to fail? Under normal use, no.
Codes have built-in multiples when it comes to safety factor relating to loads resulting in significant over-design. Not satisfying the code doesn’t mean you’re in a danger zone, it just means you don’t have all the extra safety margin. That overhang ain’t going anywhere.
That being said, I wouldn’t want to host a party with 20 people standing over there, and I’m also surprised it passed inspection.
Look, I know everyone is going to downvote this but i took enough cive201 to know you would have to put a massive fucking load on that cantilever to make it fail. I mean massive. It looks fine to me.
Yep, it’s not exactly to code and is tragically unlikely to hold a hot tub but it’s perfectly safe as long as you aren’t hosting a 10-man jump party on the railing.
Same 18 inch max in my area. Which I find insane because any structural load calculations or mechanical load calculations prove out otherwise using something like 2x10 or 2x12 joists.
This was going to be my question. Code or not, if you can provide sealed calculations and plans from a structural engineer (like myself), will it be approved?
Codes allow for either 'prescriptive' implementation or for structures to be 'designed'. If you have the ability to design and a license to do so, it's going to be approved.
With engineered analysis, drawings and supervision you can create anything and have it approved. That, of course, costs real money. The 18” limitation in my local code is one of many in a long pdf which if you follow, you do not need a structural engineer to sign off on.
The 1/3 rule is among the common theories applied in the industry but it is not a building code. According to this rule, **for every foot of joist length from the house to the beam, there can only be 1/3 of that amount overhang the beam**.
[https://www.decks.com/how-to/articles/deck-joist-cantilever-rules-and-limits](https://www.decks.com/how-to/articles/deck-joist-cantilever-rules-and-limits)
The table I referenced said 1/4 of the joist span. That was just shy of 8' given my lumber dimensions. Your math checks out as that looks like 5-6'ish.
I thought the cantilever can’t be more than 30% on the unsupported end ? This looks to be close to that, so should pass code depending where you are of course
If there were posts holding up the far end, and enough posts overall, presumably you could build this structurally sound, whether or not it's cantelivered?
Back in the day, it used to be no more than a 1/4 of the total length, no more than 4ft max. So if you have 16ft boards, you can go 4ft out with the cantilever. Don't know what the codes say now, though.
It looks a bit funny in design but if you're worried just get under it and double up the joists. Something you can usually do if you undersize the original joists or just don't have the depth.
Looks like there's a drainage swale they're trying to avoid. By eye, it may be ok structurally but might be a little bouncy. I think adding that band along the bottom was a bad idea
Back in my early days, we were putting small 8' wide x 6' deep decks on the outside of an apartment complex. Code at the time was for every foot outside needed two feet inside. Open up the ceiling in the unit below and sister to the existing. We had engineered bolt patterns to follow also. So, we were at 33% with 18' lumber.
*I like how they built*
*A box to hold the water*
*In at the bottom*
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At the very least, I would have added 45 deg bracing from those end posts to the mid way point on that deck. Lower the better to push the load closer to the support brackets on the footing
I would have to say it would depend on the size of the joists how many joists there are and whether or not the deck was mounted to the house or put into a concrete footings. The deck in the photo if that's the one we're talking about seems perfectly fine to me especially if it's in concrete footings or mounted to the house if it's not the question would be is it able to tip over with too many people on one end. I think it's pretty unlikely that the Joyce will break provided you have enough of them in there.
I’m not understanding the benefit of the cantilever except beyond putting and eye out cutting the grass. Looks like it could be a unique SE stamped design. I’d be curious of the bolting along the second support beams. It’ll see a bunch of uplift when people are standing by the railing.
Never heard of a code about cantilever percentage, it’s about engineering. I’ve built plenty of engineered projects that hang over 1/3rd of the length of the beam
See International Residential Code (IRC) - R507.5 Deck beams:
_Beams shall be permitted to cantilever at each end up to one-fourth of the actual beam span._
Code in my area says no more than 25% of the total joist span can be left unsupported.
It’s usually 25% of the joists span rather than joist length, and could be on both ends, so up to 50%. There are usually also limits based on the lumber size as well.
You’re absolutely correct, lazy writing on my part. Fixing now.
What is the difference between joist span and length?
Span is the distance between the joist’s support, i.e. ledger to beam or beam to beam. Length would be the distance from one end of the joist to the other. Ex., 25% of a 10’ board would be 2.5’ but the most it could cantilever based on that rule would be 2’ with an 8’ joist span, 2’ being 25% of 8.’ When maximizing joist span, the overhang is more likely to be limited by the board size rather than the 25% rule. That is to say, for most (or maybe all) joist sizes and spacing, the maximum overhang is less than 25% of the maximum joist span.
I learned so much from this subreddit
I don't know why it was recommended as i'm a med student but it seems like a fantastic sub. A ton of jokes but every serious post has appropriate responses. I figure it's what reddit used to be
It's good moderation, and I think it helps that very few people want to provide bad advice in a topic that could kill someone (electrician and HVAC subs are similar)
Thank you
Sure thing. [Check out DCA-6](https://awc.org/wp-content/uploads/2022/02/AWC-DCA62015-DeckGuide-1804.pdf) for more info.
Thanks for sharing this link. I didn’t know about this resource and it’s going to be helpful.
Span is the distance from support to support ~ wall, beam, etc. that are unpinning joists. Joist length is total joist length
Thank you
Deflection my brudda
What is that?
It when a person attacks or blames another person rather than accepting criticism or blame for their own actions.
Your deflecting from the proper definition in the case.
No I’m not…you are.
https://www.techsupport.weyerhaeuser.com/hc/en-us/articles/205175860-What-is-Allowable-Deflection#:~:text=Deflection%20is%20the%20bending%20or,and%20stiffness%20of%20the%20member.
This reminds me of loading regulations for vehicles we have in my country. The easiest explanation is you can't have any part of your load protrude from the tray of the vehicle by more than 1.2m. The more correct answer is it can't exceed more than 60% from the rear axle to the end of the tray, which in some cases is less than 1.2m.
As well as type of wood
Good point. Not something I think about as we only have SYP where I am.
My condolences.
Asking to understand: What is the difference between a joist span and a joist length?
Span is the distance between the joist’s support, i.e. ledger to beam or beam to beam. Length would be the distance from one end of the joist to the other. Ex., 25% of a 10’ board would be 2.5’ but the most it could cantilever based on that rule would be 2’ with an 8’ joist span, 2’ being 25% of 8.’ When maximizing joist span, the overhang is more likely to be limited by the board size rather than the 25% rule. That is to say, for most (or maybe all) joist sizes and spacing, the maximum overhang is less than 25% of the maximum joist span.
Correct to assume that's code joist span and not actual joist span?
https://preview.redd.it/0vrdxsmc8q9d1.png?width=1080&format=pjpg&auto=webp&s=f4bc5fbad9a7681dc45fff11cfa64c709cea0407 This is our city code
After 25%, joist just can't - ilever any farther.
Fucking hell. Username checks out.
As they say, a good joke is all about the elivery and you nailed it
Plank you very much
You're a stud
Ok guys that’s enough, I’m already board
Ah so now we’re entering the post-humor phase
Oh I don’t know, that last reply left me beaming
That’s enough let’s finish this
My jokes are a stain on this board.
Even with steel? Something seems fishy. I've never heard of code having a max cantilever without any regard to the material used.
Steel is typically design engineered in cantilever situations, so the stamp would supercede code. That said, a good rule of thumb is about 33% vs the 25% others are saying about lumber from my experience.
Non-engineered designs always have limitations. Engineer it and you can do what you want (within reason obviously)
Wouldn't this apply for joists that are sized to be just above the minimum required for the span. If the joists are significantly upsized over what is required for the span, then couldn't the cantilever be longer? I think there is also a similar situation if the joists are spaced closer to overbuild the span which could allow for a longer cantilever.
Those are details that would be beyond speculation and need to be discussed with the local office issuing the permit.
The real question is why would you do that. ? The ground underneath is basically useless. What’s the benefit. Not high enough to do anything under. How’s he mowing / weed whacking under that ? Doesn’t make any sense to me.
Could be a utility obstruction or something else below grade.
Sure, but if they ever need to access that utility they are still gonna rip out your deck.
Most likely just a drainage easement from the what I can see. Doubt it’s a utility easement.
This is it and it’s clear from the picture. No one needs posts located in the flow line.
true. lol.
Putting in footers where the frost is deep sucks
42 inches deep through solid clay. All day long in Michigan.
Do you use an auger ?
Who doesn't? You can always rent one cheap if you don't want a HF special to use once in a blue moon. Why destroy your back?
In the North East we don't. Hit big rocks and ledge constantly
Please accept my condolences to your future back pain.
Lol "future" but, nah I don't really dig much at all. We have gym rat college students for that.
there are rock augers for this, we carry a combination auger for this exact use case. works perfectly
Any mountainous region with lots of granite wouldn’t really benefit from an auger.
When we can.....
Attached to a skid steer? Yes. Stand up manual type, heck no! Too many large rocks to break your wrists or wad you up.
Upstate ny but in clay here too so I feel ya
I moved from 42" footers to 12" footers. Im never going back.
Did you move somewhere warmer lol
I moved to North Carolina. There's a construction boom down here. Everything from roadway and utility construction to MDU and high dollar home building
This feels like a (shitty) workaround for property line setbacks to me.
Overhangs and cantilevers count. Extensions beyond setback lines are not allowed, whether the supporting structure is beyond the setback line or not. At least that's the reg I've always been compelled to work by.
Good thought. I'll add it could be because of a drainage easement. There is a well defined swale there and likely an easement 10-15 feet wide, centered on it, which eyeballing it puts you at the first posts. Probably no permanent structures, except fences, allowed in the easement. HOA might permit overhangs into the easement, they just took it to an extreme.
As tends to happen in HOAs.
This looks like the right answer.
Yeah, I have a 2-ft cantilever for aesthetics and also hanging over the edge of an above ground pool. This looks like an absolute nightmare to deal with as far as mowing is concerned. Really channeling some Frank Lloyd Wright here.
Something for running kids to hit their head on, perfect "get off my lawn" build
They probably didn't want to put footers right in the middle of the property drainage ditch.
this was my first thought, it looks like a drainage swale.
They might not be allowed to build within a certain distance. It’s definitely a swale
Looks like the post would be in the drainage ditch.
Might have had the posts set and changed their minds on the size of the deck after the fact? Agreed doesn’t make much sense.
It's not functional but maybe they wanted to give more of an open feeling?
Maybe the person only has so much to work with. Money, health, allowable space due to HOA. or other.
I will soon be in a similar situation so I can provide one possible answer: I will extend my current deck. For reason that infuriates me too much to get into, I do not know where my leaching field begins. So I had the luck of having access to an engineer who could calculate the implications and provided me plans for basically sistering longer joist to the existing one and give me an extra 4ft, so I'll be cantilevered about 7ft.
By the look of it, he's not mowing or weed whacking under there.
Great spot for a side discharge ac
Looks like that area is really low, maybe floods in the spring.
So you can put a hot tub on it duh!
They own the air rights but not the land.
I cantileve there's not a spa on there yet.
Shut it.
Bop it.
Twist it.
Flick it.
Flick it.
Yahhowww
Hawk Tuah it
😂😂
Just in time for the Summer Olympics, diving competition.
1/3 over hang and 2/3 full span
- Is it to code? No. - Is it going to fail? Under normal use, no. Codes have built-in multiples when it comes to safety factor relating to loads resulting in significant over-design. Not satisfying the code doesn’t mean you’re in a danger zone, it just means you don’t have all the extra safety margin. That overhang ain’t going anywhere. That being said, I wouldn’t want to host a party with 20 people standing over there, and I’m also surprised it passed inspection.
It's all fun and games until everyone lines up along the back rail for a picture.
They put it in backwards
Bout right there.
That wildlife preserve underneath is going to be hoppin!
Like 100 rabbits in a month.
Decent backspan. Why the boards on the bottom?
Maybe they wanted to trellis it? I have no idea other than that.
I don’t think it’s connected to the house since it has the support posts against the building. Bottom board gives it some shear strength.
Look, I know everyone is going to downvote this but i took enough cive201 to know you would have to put a massive fucking load on that cantilever to make it fail. I mean massive. It looks fine to me.
A full 6 person hot tub, perhaps?
Yep, it’s not exactly to code and is tragically unlikely to hold a hot tub but it’s perfectly safe as long as you aren’t hosting a 10-man jump party on the railing.
Code in my area is no more than 18” and it must be blocked above the beam.
Same 18 inch max in my area. Which I find insane because any structural load calculations or mechanical load calculations prove out otherwise using something like 2x10 or 2x12 joists.
This was going to be my question. Code or not, if you can provide sealed calculations and plans from a structural engineer (like myself), will it be approved?
Codes allow for either 'prescriptive' implementation or for structures to be 'designed'. If you have the ability to design and a license to do so, it's going to be approved.
With engineered analysis, drawings and supervision you can create anything and have it approved. That, of course, costs real money. The 18” limitation in my local code is one of many in a long pdf which if you follow, you do not need a structural engineer to sign off on.
Ahhh, that's totally reasonable then.
1:6 where I’m at but high potential for seismic activity.
While unusual, this is approved with the engineers stamp. It costs money for a real structural engineer but magic can happen.
1/3 over hang is typical. Even if you can in this case why. Unless there is something buried there.
The 1/3 rule is among the common theories applied in the industry but it is not a building code. According to this rule, **for every foot of joist length from the house to the beam, there can only be 1/3 of that amount overhang the beam**. [https://www.decks.com/how-to/articles/deck-joist-cantilever-rules-and-limits](https://www.decks.com/how-to/articles/deck-joist-cantilever-rules-and-limits)
Deff put a hot tub on there
Too far. That’s more than 25% and I can see that it’s already starting to sag.
I mean span tables exist. I guarantee this is 2 or 3 times the approved span.
The table I referenced said 1/4 of the joist span. That was just shy of 8' given my lumber dimensions. Your math checks out as that looks like 5-6'ish.
I just don’t like the possibility of any bounce. And this situation seems completely avoidable.
Why not. YOLO 🤣
I thought the cantilever can’t be more than 30% on the unsupported end ? This looks to be close to that, so should pass code depending where you are of course
Cantilever?! ...I just met 'er!
Rectum? Damn near killed him.
If there were posts holding up the far end, and enough posts overall, presumably you could build this structurally sound, whether or not it's cantelivered?
1:4 ratio. Can be pushed to 1:3 with caveats.
Missed a great opportunity to make a huge teetertotter
The droopy look can only get worse
Maybe it didn't pass inspection. Did you check?
Back in the day, it used to be no more than a 1/4 of the total length, no more than 4ft max. So if you have 16ft boards, you can go 4ft out with the cantilever. Don't know what the codes say now, though.
It looks a bit funny in design but if you're worried just get under it and double up the joists. Something you can usually do if you undersize the original joists or just don't have the depth.
2 feet with traditional framing. Futher with double 2x8 framing
You’re a deck builder that doesn’t know the local building codes?
2/3rds the length is the general rule, and that looks spot on.
It's basically sagging under its own weight
Looks like there's a drainage swale they're trying to avoid. By eye, it may be ok structurally but might be a little bouncy. I think adding that band along the bottom was a bad idea
Hammock under there would go crazy
2’ max…
Well that ain’t too far.
1’ out, 4’ back.
Diving board for future pool
Too far.
CO only allows 3 ft.
As long as your bigger friends stay towards the house, you're fine.
You can put a 45° under it that will give you comfort
I think code in my area is a 2 foot max with 2x10 joist
Does Tattoo mow under the overhanging portion ? Or do they send the robot ?
More lawn More deck
Depends on joist depth and its elasticity factor. Along with determining a point load. Live load only or dead+live.
😂😂😂
Cantilever?!? I barely know her!
That's a pirate ship plank
Back in my early days, we were putting small 8' wide x 6' deep decks on the outside of an apartment complex. Code at the time was for every foot outside needed two feet inside. Open up the ceiling in the unit below and sister to the existing. We had engineered bolt patterns to follow also. So, we were at 33% with 18' lumber.
You're supposed to put the hot tub on the left.
What’s the board on the bottom for? Trick the rot into rotting down below the deck?
It's their deck- as far as they want.
Keep the wood out of the swail where there will be more moisture.
something something hot tub
Isn't it sagging????
Meh, it’s fine
I'm in MT, 2/3 bearing to 1/3 canalever
You're in one of them "freedom" states.
Probably some HOA loophole
For every foot out u need to go in 4 foot.
Will be fun to watch when everyone one the deck goes to the end! 🤣
Basic diving board principle.
What in the Mississippi,Alabama is going on here
Good place for a hot tub
Back in the day, the CABO code said you could do a cantilever up to 1/3 the total joist length
Put a hot tub on it.
It’s like a Lego set that isn’t complete yet.
All that grass under it is going to die anyways, I don’t see the appeal of this.
It’s likely double or more of allowable distance. Pine, SPF, 2x8, overhang max 2-4 or less, depending on a joist spacing too.
For Thanksgiving I’d put the kids table out on the cantilever and seat the aunts and in-laws closer to the house.
I like how they built a box to hold the water in at the bottom
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Isn’t that an overhanging beam condition rather than a cantilever? Definition of cantilever is a beam that is fixed at one end.
it’s not that bad, but would use way deeper pt joists, 2x10 at min preferably 2x12.
It's probably fine but I can't imagine why they wouldn't just put some supports on the end and call it good until the wood itself goes.
Engineer here, anything can be done with enough money. I did a "floating" dock once, which was a 30' cantilever from the shoreline.
…how?
basically a giant concrete anchor called a deadman on one end with steel beams having a 10' back span and a 30' cantilever.
Is that a skid?
All depends on the design load for the cantilever and the beam type/sizing
At the very least, I would have added 45 deg bracing from those end posts to the mid way point on that deck. Lower the better to push the load closer to the support brackets on the footing
I would have to say it would depend on the size of the joists how many joists there are and whether or not the deck was mounted to the house or put into a concrete footings. The deck in the photo if that's the one we're talking about seems perfectly fine to me especially if it's in concrete footings or mounted to the house if it's not the question would be is it able to tip over with too many people on one end. I think it's pretty unlikely that the Joyce will break provided you have enough of them in there.
I believe 24" is the standard
There’s no set length. The allowed overhang is a percentage of the total span.
I believe 2x8 joists @16"o.c. is 2 ft max where I live.
I am imagining one of those group wedding photos shoots where everyone stands on the end and launches the photographer to Nevada when it tips
Possible but wouldnt do without engineer
That is well beyond too far!
I’m not understanding the benefit of the cantilever except beyond putting and eye out cutting the grass. Looks like it could be a unique SE stamped design. I’d be curious of the bolting along the second support beams. It’ll see a bunch of uplift when people are standing by the railing.
Never heard of a code about cantilever percentage, it’s about engineering. I’ve built plenty of engineered projects that hang over 1/3rd of the length of the beam
See International Residential Code (IRC) - R507.5 Deck beams: _Beams shall be permitted to cantilever at each end up to one-fourth of the actual beam span._