• Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by first logging in then clicking here: Upgrades

Type IB - rated floor assembly required over crawl space?

rjjh

rjjh

Registered User
Joined
Nov 11, 2021
Messages
18
Location
LOS ANGELES
Hi!
We are proposing a Type IB, type R-1 single story hotel, that is non-separated.
The units are prefabricated and placed over an unoccupied crawl space, will the floor assembly need to maintain a 2HR rating per Table 601? or are there any exceptions to being over a crawl space over grade?
 
No exceptions. A floor over a crawlspace is still a floor. Type IB construction is fireproof. The intent of the fire protection ratings in Type I construction is at least as much to keep the structure standing as it is to separate portions of the building from other portions. In a building of Type I construction, floors above crawlspaces absolutely must provide the fire-resistance rating called for in the table.

That said, I can't imagine why a building that's a single story R-1 needs to be Type IB construction.
 

722.6.2.4 Floors and Roofs​

“In the case of a floor or roof, the standard test provides only for testing for fire exposure from below.”

If you treated the floor assembly as including noncombustible soil, and the crawl space as a cavity within the floor assembly, then you could see if you could make it work on a performance basis. The problem arises where the perimeter of this assembly has walls that have vents or any other opportunity to introduce fire from the exterior into the cavity.

You described it as an “unoccupied crawl space”, but that could be any number of things, including a raised post-and-beam foundation where wildfire could spread to vegetation underneath.

If you insist on a construction type that requires a fire rated floor, I suggest you contact the modular fabricator and ask them how they have successfully constructed such a floor assembly in the past. This can’t be their first rodeo.

Regarding the required fire rating and the comments in the previous posts, have you considered this:

602.1.1 Minimum Requirements​


A building or portion thereof shall not be required to conform to the details of a type of construction higher than that type which meets the minimum requirements based on occupancy even though certain features of such a building actually conform to a higher type of construction.
 
Some gimmies on rating (sort of), but not combustibility....

711.2.6 Unusable Space​


In 1-hour fire-resistance-rated floor/ceiling assemblies, the ceiling membrane is not required to be installed over unusable crawl spaces. In 1-hour fire-resistance-rated roof assemblies, the floor membrane is not required to be installed where unusable attic space occurs above.
 
Yikes said:
Regarding a 2 hour floor, I suspect the original poster has not yet considered down-rating the construction type per 602.1.1.
Click to expand...
I agree with you. R-1 at a single story seems wholly unnecessary to use Type I-B. Just taking it down to II-B would do away with the fire-resistance rated floor per Table 601 while having an allowable area, pre-frontage increase, of 16,000sf with a 13R system or 64,000sf with a full 13 system.

@rhughes411, why Type I-B?

2021 IBC 602.1.1 Minimum Requirements​

A building or portion thereof shall not be required to conform to the details of a type of construction higher than that type which meets the minimum requirements based on occupancy even though certain features of such a building actually conform to a higher type of construction.
 
classicT said:
I agree with you. R-1 at a single story seems wholly unnecessary to use Type I-B. Just taking it down to II-B would do away with the fire-resistance rated floor per Table 601 while having an allowable area, pre-frontage increase, of 16,000sf with a 13R system or 64,000sf with a full 13 system.

@rhughes411, why Type I-B?

2021 IBC 602.1.1 Minimum Requirements​

A building or portion thereof shall not be required to conform to the details of a type of construction higher than that type which meets the minimum requirements based on occupancy even though certain features of such a building actually conform to a higher type of construction.
Click to expand...

Even downgrading to type II-A would reduce the floor rating to 1-hour -- which would then qualify for the exceptio noted by steveray.
 
classicT said:
I agree with you. R-1 at a single story seems wholly unnecessary to use Type I-B. Just taking it down to II-B would do away with the fire-resistance rated floor per Table 601 while having an allowable area, pre-frontage increase, of 16,000sf with a 13R system or 64,000sf with a full 13 system.

@rhughes411, why Type I-B?

2021 IBC 602.1.1 Minimum Requirements​

A building or portion thereof shall not be required to conform to the details of a type of construction higher than that type which meets the minimum requirements based on occupancy even though certain features of such a building actually conform to a higher type of construction.
Click to expand...
  • thank you all for the feedback and points @classicT @steveray @Yankee Chronicler ! it gets a little complicated, to give a little more context on the issue and project:
    • the hotel/resort is spread out over about 10 acres, in a rural area, with a clubhouse and pool, mixed used non-separated, and fully sprinklered NFPA 13
    • the hotel design was based off of prototype shipping container units on a nearby site that is in a moderate WUI. the prototype plans were approved by the city and state, and the design and construction type (IB) was used as a basis to streamline the approvals of the larger project. the larger site is only a few miles down the road and not in a WUI.
    • the following design changes occurred while the plans were in the city dues to ownership requests:
      • original design was composed of repurposed shipping containers (14ga continuously welded steel underbelly, roof, and exterior walls) where fire rating was hardly an issue. plus it has approved alternate means of construction by the state. the owner selected a container fabricator without fully sharing the bid details, but the fabricator stated that they could meet the design intent using purpose built instead of repurposed containers.
      • the original design was also slab on grade (which was changed to crawl spaces after the LAHJ submittal) for ease of site installed MEP connections, and ratings were not an issue on the floor with SOG. This was requested by ownership late in the process, and the change was accepted by the city.
  • While I agree the construction type is excessive, it was stated in the contract documents from the start of the project; despite the changes and fabricator statements. Now that they are almost in fabrication of purpose built containers, they are expressing issues, and are stating that they cannot meet standard container criteria listed in the architectural and structural drawings.
  • The plans were approved by the city as Type IB, therefor I do not see how 602.1.1 would apply in the reverse situation that the approved construction type is greater than that proposed by the fabricator.
  • I am left either continuing to push back on the fabricator to uphold the contract docs, since it was largely an overlook on them, for not meeting the BOD parameters, but also a huge challenge, or alternatively submitting a revised design and construction type change (to IIB, IIIB, or even propose VB since it appears within the allowable area of the project) to the city while the project is under construction. So I am trying to weigh my options, but both have cost and delay implications.
  • a caveat is that the fabricator still needs to submit the module designs to the state and obtain approval for the modular portions of the project, which are largely excluded from local jurisdiction. the fabricator thinks this is a local building official oversight, but I disagree and think they have every right to uphold the original construction type of the project in it's final site installed form.
 
Last edited:
rhughes411 said:
  • thank you all for the feedback and points @classicT @steveray @Yankee Chronicler ! it gets a little complicated, to give a little more context on the issue and project:
    • the hotel/resort is spread out over about 10 acres, in a rural area, with a clubhouse and pool, mixed used non-separated, and fully sprinklered NFPA 13
    • the hotel design was based off of prototype shipping container units on a nearby site that is in a moderate WUI. the prototype plans were approved by the city and state, and the design and construction type (IB) was used as a basis to streamline the approvals of the larger project. the larger site is only a few miles down the road and not in a WUI.
    • the following design changes occurred while the plans were in the city dues to ownership requests:
      • original design was composed of repurposed shipping containers (14ga continuously welded steel underbelly, roof, and exterior walls) where fire rating was hardly an issue. plus it has approved alternate means of construction by the state. the owner selected a container fabricator without fully sharing the bid details, but the fabricator stated that they could meet the design intent using purpose built instead of repurposed containers.
      • the original design was also slab on grade (which was changed to crawl spaces after the LAHJ submittal) for ease of site installed MEP connections, and ratings were not an issue on the floor with SOG. This was requested by ownership late in the process, and the change was accepted by the city.
  • While I agree the construction type is excessive, it was stated in the contract documents from the start of the project; despite the changes and fabricator statements. Now that they are almost in fabrication of purpose built containers, they are expressing issues, and are stating that they cannot meet standard container criteria listed in the architectural and structural drawings.
  • The plans were approved by the city as Type IB, therefor I do not see how 602.1.1 would apply in the reverse situation that the approved construction type is greater than that proposed by the fabricator.
  • I am left either continuing to push back on the fabricator to uphold the contract docs, since it was largely an overlook on them, for not meeting the BOD parameters, but also a huge challenge, or alternatively submitting a revised design and construction type change (to IIB, IIIB, or even propose VB since it appears within the allowable area of the project) to the city while the project is under construction. So I am trying to weigh my options, but both have cost and delay implications.
  • a caveat is that the fabricator still needs to submit the module designs to the state and obtain approval for the modular portions of the project, which are largely excluded from local jurisdiction. the fabricator thinks this is a local building official oversight, but I disagree and think they have every right to uphold the original construction type of the project in it's final site installed form.
Click to expand...
Makes sense now. Thank you for sharing some of the unique details.

IMHO, you have your mind in the right spot. You are well informed and have multiple paths to choose from on how to proceed.

We hope that you can find resolution and move forward. Sounds like a very interesting project. Good luck!
 
steveray said:
Any intumescent paint to get you to 2 hours? Or hit IBC 722 and start layering up drywall....?
Click to expand...
neither are a bad idea to propose, would you recommend any intumescent pain products? and have you used them in the past without issue?
 
steveray said:
Any intumescent paint to get you to 2 hours? Or hit IBC 722 and start layering up drywall....?
Click to expand...
rhughes411 said:
neither are a bad idea to propose, would you recommend any intumescent pain products? and have you used them in the past without issue?
Click to expand...
I'm not sure that intumescent paint would work...

Intumescent paint works great for individual member encasement (i.e. protection of the beams/girders/joists), but is not a great option for membrane construction. How would you deal with any penetrations of the membrane? Finding an approved firestop for the through penetrations that includes intumescent coated floor sheathing as part of the assembly is not something I have seen before. Not saying it doesn't exist, but it would be a novel approach IMHO.
 
To be honest, I saw lots of CONEX shipping containers when I was in Vietnam, I've been around shipping yards where they are found in abundance, and I've seen a couple of residential structures built around re-purposed shipping containers. I can't imagine any possible scenario under which a tin can like a shipping container might even remotely qualify as type I-B construction.

That said -- it sounds to me like a contractual issue. Whatever your role is (if you mentioned it, I missed it), the fabricator bid on something and now doesn't want to provide what he/they contracted to provide. Seems to me the solution is to void their contract and try again.

What about spray-applied, cementitious fireproofing on the underside of the floors?
 
steveray said:
I was kinda thinking it was "one piece" being the bottom of the box....
Click to expand...
Solid point.

Although, I think most shipping containers use wood sheathing for their floor (either nominal or 1" T&G marine-ply). This could have been another issue with the Type I-B designation. Being that the OP indicates that the plan is to fabricate new units, it is unknown what the floor consists of.
 
Yankee Chronicler said:
I'm pretty certain they don't.
Click to expand...

Shipping Container Flooring (from https://www.discovercontainers.com/)​

To understand shipping container flooring consider the original purpose of shipping containers. They have been designed to withstand the punishment of long distance ocean travel and to protect the goods inside of them during transport.

Most often, shipping container floors are one inch marine plywood made from tropical hardwood such as Keruing or Apitong. These types of hardwoods unfortunately attract pests of all sorts.

To prevent damage to the goods by the insects and other critters, the wooden floors are treated with pesticides.
 
You must log in or register to reply here.
Top