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» ICC Bulletin Board » Code Chat » Building and Residential Codes -- Structural Issues » R311.2 and free standing decks/landings

   
Author Topic: R311.2 and free standing decks/landings
outsidethebox
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Just wanted to see what others thought of this.

According to IRC R311.4.3 there shall be a landing on both sides of an exterior door. Right? The width of each landing shall not be less than the door served and a min. of 36" in the direction of travel. R311.2 construction and R311.2.1 Attachment....similar means of egress componenents shall be positively anchored to the structure to resist both vert. and lateral forces.

So how does a deck ore required landing outside of an exterior door, that is free-standing, provide this positive anchorage to the primary structure? Can ANY deck that a door opens out onto be free standing?

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Vmac
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Interesting question. Concrete slabs that are often provided for exterior landings are not usually tied into the foundation around here. That would be the equivilent of tying the deck landing to the structure.

My real concern is that whatevere means of construction used for the deck be structurally sound. One potential issue, if they are not tied together, is what happens in the event of seismic activity. Would the resulting motion result in the failure of the deck and prevent an escape route from the structure?

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There is never a problem until someone creates a problem.
Vmac

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High Desert
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I think the code's pretty clear - you can't have a free-standing deck or landing at a required egress door. I think you can have additional decks or landings at other doors that don't need to be attached.

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"If it ain't broke, fix it 'til it is"
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DRP
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Free standing does not neccessarily mean unattached, it means that all vertical loads are carried on posts vs on a ledger. See fig 23 in DCA6. There is another pic of post to foundation bolting attachment in a publication I can't bring to mind at the moment. Basically thru the post and wall.
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Kilitact
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similar means of egress componenents: similar to balconies, stairways etc. not a free standing deck

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In seeking wisdom thou art wise; in imagining that thou hast attained it - thou art a fool.
Lord Chesterfield

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outsidethebox
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I think that fig 23 has me busted. I assume the lag bolt spacing is far less than that given in figure 19. Although in fig 23 it says its spacing is 16" o.c., so why bother with the free standing portion which costs the permitee another concrete pier(s), 6x6 column(s) and beam(s)?

Now what happens when the house is brick veneer?

[ 06-03-2009, 09:37 AM: Message edited by: outsidethebox ]

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DRP
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Code or not I've built my last ledger supported deck. The only question then remains whether to attach to the house and eliminate knee bracing or knee brace and lightly attach to the building. If I'm against the house there will be some form of attachment to guarantee alignment, it is simply a matter of which method is used to develop the lateral resistance required. That IMO is the reason for the 16"oc lags or knee brace options.

This is from the "Manual for the Inspection of Residential Wood Decks and Balconies", it was the other connection I was remembering;
 -

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Vmac
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You are correct, it does say that all exit egress componenets shall be positively anchored to the structure. So I am sure all will now be checking to see if the concrete pad often used is anchored in this fashion with rebar.

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There is never a problem until someone creates a problem.
Vmac

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outsidethebox
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We don't allow 36x36x4 concrete slabs to be poured outside of an exterior door. They have to reabr it to the existing structure and then provide some sort of foundation sytem to 42" below grade such as piers or foundation. Or they can use wing walls. But a concrete pad alone is a no go. Of course I get people telling me that the cost of 2 concrete piers is about $500. I have to think these people are either making this stuff up or someone is gauging them.
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DRP
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What would you do it for?
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Vmac
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DRP - I assume that question was for me. My point is that is "all exit appertenances" are required to be postively anchored to the structure. That requirement would apply to concrete pads also.

It sounds as though "outsidethebox" does just that. My guess is he is in the minority. Yet, if we are goung to make an issue of not accepting free standing landings (whether adequately braced or not), concrete slabs need to be treated the same and also anchored to the structure with rebar or (?)

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There is never a problem until someone creates a problem.
Vmac

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outsidethebox
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How much money is a couple bags of ready mix concrete, wire mesh, a couple 2x4's, 3 pieces of rebar, expansive grout, a drill bit and the post hole digger? My time is free when I do it at my house. So what is that? Maybe $100-$120 But for anybody else I'd charge about $1200 per 36x36x4 landing. [Wink]
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RickAstoria
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outsidethebox

Home owners look at total cost as it is quoted. Contractors, ect., will give a cost including labor factored in. Two of them for $500 is realistic for material cost and labor cost. Homeowners will often not do concrete work themselves. Wood framing is more common. The labor is the biter. Ther 36"x36"x4" slab itself, may be the bulk of the material cost but the labor on a slab is lower. You don't have to dig a hole which is time consuming and at $30-60/hr. labor, that'll cost unless you have an auger drill. Oh well.

OTB, the people saying that is probably using the simple quote from the contractor who will simply say - "It will cost you $_______". They count into the cost for material and labor and some contigency amount.

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Kilitact
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R502.2.2: Where supported by attachment to an exterior wall, decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads as applicable. freed standing decks are not required to be attached.

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In seeking wisdom thou art wise; in imagining that thou hast attained it - thou art a fool.
Lord Chesterfield

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outsidethebox
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Kilitact, I don't se how your last sentance, which is not written in the code, is accurate. R311.2.1 says that the means of egress components shall be positively anchored to the structure to resist both vert. and lateral forces. R50202 does not make an exception to this. It allows a deck to be free standing and not attached to the primary structure. I suppose a deck with no door component/landing requirement.
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Kilitact
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R311.2.1 is talking about exterior egress balconies, exterior exit stairways and similar means of egress. This section is not referring to decks, which aren’t similar in design or if free standing, dependent on the primary structure for support, Vmac’s example of a slab, is another way to look at this. R502.2.2 is specific to the design for decks

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In seeking wisdom thou art wise; in imagining that thou hast attained it - thou art a fool.
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Vmac
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OK guy's I finally resorted to pulling out the Commentary to the IRC

it reads - "If an exterior wall is used to support a deck, the deck framing must be positively attached to the building structure." ............ "If it is not (positively attached) the deck must be self-supporting."

[ 06-05-2009, 12:48 PM: Message edited by: Vmac ]

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There is never a problem until someone creates a problem.
Vmac

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outsidethebox
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Which also says nothing about a landing component nor means of egress. Only decks. We have many decks, free standing or not, that do not have a door component on them thus no need to attach them positively to the primary structure.

See code commentary for 311.2.1 Too long to write it down.

Especially read the last sentence.

[ 06-05-2009, 12:33 PM: Message edited by: outsidethebox ]

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Kilitact
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decks are not balconies,exterior stairs or concrete slabs.

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In seeking wisdom thou art wise; in imagining that thou hast attained it - thou art a fool.
Lord Chesterfield

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outsidethebox
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Nope. A deck is not a balcony nor a concrete pad nor a bag of groceries. But it is a component of a means of egress and required landing if being installed outside an exterior door.

[ 06-05-2009, 12:49 PM: Message edited by: outsidethebox ]

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Kilitact
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otb; You are correct, its not a bag of groceries! now, its also not included in R311.2.1 attachment, R311.4.3, landings at doors is the code section for landings.

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In seeking wisdom thou art wise; in imagining that thou hast attained it - thou art a fool.
Lord Chesterfield

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Vmac
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Commentary again -

Definition of deck - DECK = An exterior floor system supported on at least two oposing sides by an adjoining structure and/or posts, piers or other independant supports.

"Where an exterior floor system is supported on a minimum of two opposing sides, it is a deck. The support may be totally by post or piers, or, as often occurs, by the dwelling on one side with posts and piers on the opposite side."

Language above directly from the IRC Commentary.

This would seem to apply to ALL Decks, whether they are used as a means of egress or not. Now back to the previous post, IF SUPPORTED ON ONE SIDE BY THE HOUSE OR STRUCTURE, it must be positively attached to said house or structure. IF, IF, IF. If it is not attached tot the structure it must be a free standing deck whether it is used as a front porch, means of egress or a dance and party platform.

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There is never a problem until someone creates a problem.
Vmac

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outsidethebox
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But it is. It is all inclusive.

Similar means of egress components. I would believe that it is certainly a similar means of egress as that of a balcony with exterior stairs, wouldn't you?

And R102.1 Where in any specific case different sections of this code sppecify different materials, methods of construction or other requirements, the most restrictive shall govern.

Or better. Argue to me how a concrete pad 36x36x4 is a component of the means of egress but the landing portion of a deck is not as well as any staircase attached to the deck?

[ 06-05-2009, 01:04 PM: Message edited by: outsidethebox ]

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Vmac
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I have retracted my position on the concrete pad since opening the Commentary where it specifically notes that free-standing elements are acceptable. Munch, munch, munch. Does that sound like eating crow?

The front porch you describe is an exteriro floor, most closely resembling a deck (by definition)

The commentary specifically allows free-standing decks.

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There is never a problem until someone creates a problem.
Vmac

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Francis Vineyard
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__________________________________________________
Can ANY deck that a door opens out onto be free standing?
__________________________________________________

Yes, however for example; an IRC dwelling has three exterior doors and they all are located over a deck, at least one of the decks must be attached to the structure (with footings) for the required exit door.

Now how could a balcony not be positively anchored? Never mind.

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mcb
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The deck may not necessarily be the means of egress component. Generally a house needs only one means of egress (R311.4). Therefore, a rear door/slider would not be the means of egress component and can have a "floating" deck.
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outsidethebox
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I don't think that is exactly true or quite right. Every dwelling shall have not less than one exit door conforming to this section. That is how R311.4.1 reads. That does not mean that every other exterior door is not subject to the 2006 IRC all of a sudden. If the attachment requirement in section R311.2.1 is only for the "not less than one exterior door", why does it include the line "similar means of egress components"? There would not need to be this requirement for extra components, right because only the front door would be applicable?
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Francis Vineyard
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IMHO generally accepted practice has the front entrance door as the minimum required exit door. This follows IBC when only one exit is required.

This exit door as mcb pointed out shall be side hinged, 36x80 and exterior grade.

Note Section R311.4 having the required exit door is singular. There is the required exit door and other doors that may be exterior, sliding, interior, garage, etc.

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Paul Sweet
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If you're in earthquake or flood country the deck might need to be independent of the house.
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RickAstoria
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All landings are decks but not all decks are landings. If the deck serves as a landing then landing rules applies.

The saying goes as follows. All squares are quadrilaterals but not all quadrilaterals are squares.

Simply put a landing is a deck. It is structurally nothing more then a floor diaphragm supported by posts/beams and/or walls.

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George Roberts
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"Attachment....similar means of egress componenents shall be positively anchored to the structure to resist both vert. and lateral forces."

The requirement of the attachment is given - the landing should not move relative to the structure as a person moves through the doorway.

A slab on grade will not move.

What will move:

a slab with wheels that rolls on another slab.

or a cantilever deck that deflects more than the l/360 that a floor requires.

or a set of floating pads on a decorative pond.

[ 06-09-2009, 05:31 PM: Message edited by: George Roberts ]

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CSL
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Outsidethebox has a very legitimate question. He is discussing the requirement for means of egress components (like a landing) to be "positively anchored" to the structure. Thus creates the question..."what if a free standing deck is used as the landing...wouldn't that violate the section?

I ran into this question a few months ago, but in regard to writing about the 2009 IRC. I discovered that this statement goes away in that edition, and thus so does the issue.

This entire section is re-worked in the 09 IRC and it now includes the phrase "...or shall be designed to be self-supporting".

I would be comfortable to allow a "self-supporting" deck to act as a means of egress landing as an "alternative" to the 06 IRC with the evidence of equivalency being the provisions in the 2009 IRC.

DONE.

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RickAstoria
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Then the deck shall meet the stricter provisions because the deck is both a deck and stair landing and the deck shall meet the requirements of both. The stricter provision applies.
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RickAstoria
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All landings of exterior stair cases are decks but not all decks are landings.

Interior stairway landings are floor diapragms and obviously needs to be integrally fasten and tied to the rest of the structure.

Deck is a floor supported by walls or posts. An exterior stair landing is a floor supported by posts or walls.

An interior landing of an interior stair is a a floor supported by walls or posts as well.

The provision of an exterior deck to not have to be positively attached is for structurally independent decks. But landings of a stair requires it. When a deck is used as part of a means of egress (exit discharge) of one or more buildings then the deck needs to be positively connected to each building that it serves even if it is structurally independent. This is so that the decks/landing does not pull away from structure.

When a deck is serving as a landing then it is a landing and deck at the same time and serves two roles and is permitted in code to serve more then one function. A foundation wall can also serve as a retaining wall as well. This duality of role and purpose is legal and code permits it.

Just call this spade a spade. This deck is a landing and a deck in one. Serves both purpose and shall comply with both codes requirements.

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Kilitact
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If your refering to CSL's post,there's one requirement.

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In seeking wisdom thou art wise; in imagining that thou hast attained it - thou art a fool.
Lord Chesterfield

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