Head clearance for ships ladder to access storage area in tiny house

[dmoreholt]

Hi,

I have a client with an already built mobile tiny house. He wants to put it on a permanent foundation and we are reviewing the design for code compliance.

He has a ships ladder to access a small lofted area for storage (~7'x7' with 4' ceiling), and the ceiling profile is such that the ceiling drops slightly from the storage area to the space over the ladder (goes from 4' ceiling in the loft to a sloped ceiling over the stair 3'-6" over the loft floor on the high part and 2'-8" on the lower part). Our concern is with meeting the headroom requirement for the stairs. According to R311.7.10 Spiral Stairs and Bulkhead Enclosure Stairways are required to meet code requirements for stairs (R311.7) (including head height requirements) but I see no similar requirement for Ship's Ladder Stairs or Alternating Tread Devices. Are there any height clearance requirements for these types of stairs? I cannot find anything in the code about it. If there is such a requirement, I would imagine that it would allow for the clearance height to match the ceiling of the space at the top of the stairs where that ceiling is below the height requirement, but since the ceiling drops slightly at the stair any such exemption would not apply.

Location is Sussex County, Delaware, they're adopted the 2021 IRC.

 

[Mr. Inspector]

Since it is not a stairway, it would not need to comply with any stairway requirements like head clearance or landings, etc. per 2018 IRC

 

[dmoreholt]

That's what I'm getting as well from the code. Just seems strange. By the reading of the code you could have a ships ladder with 2' of head clearance and meet requirements for egress as long as the loft complies with the egress exemption for ship's ladders.

 

[Yankee Chronicler]

Is there any guidance in the IRC Tiny Homes appendix?

APPENDIX AQ TINY HOUSES - 2021 INTERNATIONAL RESIDENTIAL CODE (IRC)

ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures.

codes.iccsafe.org

 

[SCBO1]

2021 IRC, Appendix AQ, section AQ104.2, Loft access and egress (If adopted?)
The AQ1042.2 allows the stairway to be 6'2" on a ships ladder.

2021 IRC R311.7.10.1 The spiral stairway height 6'6" head clearance.
2021 R311.7.12 Ships ladders

Is there a headroom requirement for a ships ladder?

 

[dmoreholt]

I read thru the appendix and don't see any head height requirements for ship's ladders.

@SCBO1 I see that AQ104.2.2 says ladders must comply with the headroom requirements listed in AQ104.2.1 but I don't see that requirement for Ship's Ladders (AQ104.2.4, not a subsection of AQ104.2.2).

 

[SCBO1]

IRC 2021
AQ104.2 Loft access and egress
AQ104.2.1.2 Headroom (6 feet 2 inches)

 

[dmoreholt]

@SCBO1 My thinking is that AQ104.2.1.2 is a subsection of AQ104.2.1 which is the regulations for stairways accessing lofts. AQ104.2.2 cover the requirements for ladders, including ship's ladders, and don't have that height requirement.

 

[bill1952]

If it were a stair, and the loft storage (or to attic storage in a ranch house) was only 4', is headroom required? Seems like a lot of stairs and ships ladders to low storage.