Egress From Third Floor Residential

wurdan freo

It is my understanding that egress from a third floor in a single family home per the IRC requires two separate stairs. Two floors and you can have a stair and a jump platform, but three floors you will need two stairs.  Is that correct? 

I recently saw a home built. Passed through inspections and everything where there were three floors and only one stair.  The floors were labeled lower floor, second floor and third floor. The Lower floor was half garage and half bedroom. The bedroom side could be considered basement as 3-4 feet was retaining wall. The footprint was 20x45 with the garage facing the street and the bedroom facing the back. Lot sloped from back to street.

Was one stair allowed because this lower floor was not the first floor but a basement? Even so, I would have labeled the plans, lower floor, first floor and second floor. Or am I reading the code entirely wrong?

Apr 3, 14 4:59 pm
Where are you located? Local code is critical.
Apr 3, 14 8:20 pm  · 


You've got two separate issues here.  Gruen is correct in one respect; The zoning code will have a definition of what a basement is, but it's likely only defining it for the purposes of civic planning (density, parking, height limitations, etc.).

The issue you're addressing is concerning life safety, which is the building department's bailiwick.  For that definition, our 'basement' needs to conform to the definition tendered in IRC R202, 'Story Above Grade Plane', as NOT a basement. (The language creates what is known as a 'negative declaration', i.e. if the story is not 'Above Grade Plane', then it's a basement).

Also, in deference to Gruen...Check the local civic code and be sure the local jurisdiction hasn't amended the IRC definition of what constitutes a 'basement' (which they can conceivably do).

The ground floor of the building you describe sounds like it may indeed qualify as a 'basement' in terms of the IRC language, which would mean the topmost floor only requires one stair for egress.  It may or may not be a 'basement' in the eyes of the planning department, though.

Hope that helps.

Apr 3, 14 9:14 pm  · 
wurdan freo

Thanks for your insight.  The property is in Breckenridge, Summit County CO. I haven't checked the local amendments, but my assumption is that the lower level was viewed as a basement by the AHJ. Thanks for the reference to R202 as well. I will review. 

Apr 4, 14 11:20 am  · 

Did a lawsuit like this once.  First; Getting a permit or occupancy certificate doesn't mean it meets code (read the first chapters of the code and that language about permits, inspections, and co's that starts "Nothing in this chapter shall ____").  Our lawsuit was a duplex (which is single family).  The layout is garage and entry on the first level, everything above it to save on footprint.  3 stories.  Basements are also defined in the code, so you can't call it a basement. There were also 72 of these buildings so you can imagine the potential damages to correct this defect.  btw; grey area is creating a carport down there since it isn't enclosed space... So if your good, you can backdoor argue your garage condition isn't any more hazardous just because you put in an oh door.

Two exits were required per code unless amended otherwise or went through a variance..   So if you are designing it, just cya and get the CBO (chief building official) to acknowledge and sign-off that they reviewed and approved it specifically.  Call attention to this known code violation and let them decide if it's ok or not. 

Lots of ways to successfully argue this violation or meet halfway.  Some even allow alternate means of egress such as drop ladders, circular stairs, etc. (which also aren't code compliant).  I've used a commercial alternating tread device as well which complies with commercial code and takes less space on a project once to get from that 3rd floor to the 2nd.   

Apr 4, 14 11:42 am  · 

In some jurisdictions, you can exit through a window as long as the sill is at an elevation no greater than 42" AFF. At the 3rd Floor Level, the fire department can rescue you with a ladder... 

Apr 4, 14 11:59 am  · 

You do know ladder trucks are outdated equipment right?  Also... might want to check the response times versus how fast smoke envelopes.  Both smoke and fire rise. 

Why it matters to you as an architect:  You are more likely to receive a substantial injury jumping from a 3rd floor.  Not quite high enough to kill people that often. Permanent disabilities are very expensive.  That insurance company is going to seek out someone to help pay for that.  Failing to meet the minimums of the code is negligence that is extremely difficult to prove innocence on.

Apr 4, 14 1:35 pm  · 
wurdan freo

So even if you get the CBO to sign off on it... could you still be found liable in the situation you present above since you knowingly are designing in violation of code?

Apr 4, 14 1:58 pm  · 

Keep in mind the State and local codes do have amendments to the IRC.  Be sure your using the proper issue of the IRC as accepted  by your State of Local.  Lots of States are way behind  the current publication.

Apr 4, 14 3:02 pm  · 

The code allows the CBO to waive requirements based on circumstance.  And I'd highly suggest you get that notification in writing and document the conversation.  Or even specifically call it out on the code study in the drawings so no one can think you were trying to sneak it past the plan reviewer.

Apr 4, 14 3:17 pm  · 

I'm not convinced that the IRC requires a second stair from a third floor.  If it does, I would expect that the requirement would be found in Chapter 3 - Building Planning.  No reference there that I can see.  (Pre-IRC/IBC, the old UBC did have such a requirement.) 

If someone has found a current code reference that shows otherwise, I would gladly stand corrected.

I agree that local amendments could require the second stair, but I'm just addressing the requirement in the IRC. 

Apr 7, 14 6:48 pm  · 

That's weird.  I also went and looked it up.  Even in the R101 it allows for "no more than 3 stories" and I can't find where a second exit is required off the 3rd floor.  Even went back a few versions.  I stand corrected though I still swear it was in there somewhere; I can't find it, so I must be wrong and what I saw was a local amendment or UBC memories.... It isn't in the IRC.

Apr 7, 14 7:21 pm  · 
Yeah, pretty sure it's 4 stories and up. But local might override or require sprinklers.
Apr 7, 14 8:12 pm  · 

The fourth floor would move it out of the realm of the IRC and into the IBC.

Apr 8, 14 12:19 am  · 
wurdan freo

Guess I should actually read the code. Thanks for the update!

Apr 8, 14 11:36 am  · 

OK, I want to revisit this. 

I'm in the design phase for a 3 unit townhome project. One of the units is an existing single family home, the other 2 are new.

All 3 will have a third story - an "attic" story. Ideally, just one stair due to site constraints. 

My assumption: that townhomes are separated single family homes, and therefore allowed under the IRC instead of IBC due to the the definition of townhouse in the IRC:


TOWNHOUSE. A single-family dwelling unit constructed in a group of three or more attached units in which each unit extends from foundation to roof and with a yard or public way on at least two sides.


R302.2 Townhouses. Each townhouse shall be considered a separate building and shall be separated by fire-resistance-rated wall assemblies meeting the requirements of Section R302.1 for exterior walls.

I cannot find anything in the IRC (or my local code) stating that a 2nd stair is required from a 3rd story. If you think it should have a second stair, can you point me at a code reference? 

Second question: the fire separation requirement for the common wall appears to allow a single width (IE: single row of 2x6 at 16" O.C) common wall, as long as 1 hour rated. I've had others tell me it should be a double row of structurally independent studs, both sides rated (so it's built like a 1 hour fire wall). What would you do? I'm tempted to just do a double row of studs, but saving a few inches would be useful on the site. 

Sep 14, 15 11:13 am  · 

Townhomes are different from single family.  One is R-3 and one is R-5.  Review the code with this understanding.


I've built many of each and have never done provided a second stair.

Sep 14, 15 3:47 pm  · 

Never ran into the problem with 2-story + walkout basement configurations.  They are quite routine.  Only was a problem when the walkout basement itself was a full story out of ground (mountain site).

Most 2-story plus walkout houses had a deck across the back with an outside stair down to grade.  So, the second floor occupant would go down the main stair and then either run out the front door (at grade) or out the patio doors to the deck and then down the deck stair to grade.

Sep 14, 15 4:47 pm  · 

R-5? For New Jersey and Virginia but not where I am. Interesting. I can see the rationale for classification.

Cute code amendment, though.

Sep 15, 15 12:30 am  · 

Interesting. The project is in MA, and I'm glad you pointed me at the IBC because I found this MA amendment which clarifies the issue (in my case):


310.2 R-3 Replace as follows:

(removed a bunch of unimportant edits)

Townhouses (three or more attached dwelling units) more than three stories in height. Height and area and fire protection requirements for townhouses shall be restricted to those for R-2 uses. (Note: Townhouses three stories or less are also classified as R-3 but shall comply with the 780 CMR One-and Two-family Dwellings.)


Thusly, in MA, for a 3 story townhome, they consider it to be a collection of single family dwellings, separated by a rated wall as long as it's 3 stories or less. Funny that they say that a 4 story town home is an R-3, but must comply with R-2. There is no "R-5" in the straight IBC or MA edits of the IBC. 

Sep 15, 15 9:54 am  · 

I want to revisit this question ONCE AGAIN.

I recently worked on an 8 unit apartment house. This had 1st-floor garage, 2nd floor 4 units, 3rd floor 4 units. All the units have access to 2 stairs. the building is sprinklered. 

The client suggested combining the attic area into the 3rd-floor units, such that they were 2 level larger units. 

I shot down this proposal due to height constraints, but it got me thinking - would it be allowed to have a 4th floor, with a single communicating stair for a residential unit? It would be an "exit access stair" which can be open, and the UNIT and both its levels 3rd and 4th would have "access" to 2 independent means of egress within 125' of distance. This seems to me to meet the requirements of TABLE 1006.3.1.

It's been some time, but I recall that this is fairly common on the "penthouse" level in wood framed apartments.

Jan 27, 22 10:17 am  · 

In other words, can you make the top floor a townhouse with a single stair down to the living room level, and then have access to two fire exits once you flee out of the unit's front door?  I see it done all the time so I would assume it's legal in most places.  The problem might come into play with the bedroom egress windows, which might be too high off the ground.

Jan 27, 22 11:19 am  · 
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