Topic Title

There used to be a code requiring the garage floor to be a step down from the main living area floor in an attached garage to act as a fume barrier. I say used to because an architect I am dealing with says it is no longer required. Does anyone know where this was specified in the code or can anyone confirm that this is no longer required?

I am working on an accessible plan and the architect is figuring the garage floor to be flush with the first floor slab. It will then slope to a floor drain in the middle of the garage. This would eliminate the need for a ramp but I just want to make sure.

I have calls into a few building officials but have not gotten the call back yet and thought I would post this here.

Thanks in advance for any replies.

Hello Tony,

As far as I know, a minimum of 4" stepdown is still required -- fuel fumes still leak out of fuel tanks, and they still drop to the floor; so in order to avoid an explosion...the step down is still required.

Hello Tony,

As far as I know, a minimum of 4" stepdown is still required -- fuel fumes still leak out of fuel tanks, and they still drop to the floor; so in order to avoid an explosion...the step down is still required.

That's my feeling but I don't know where this is in the code to back me up. Any idea on what section this is discussed in the IRC? or even better in the Residential Code of Ohio 2006 (based on the 2003 IRC).

I had to look this up for a builder the other day and I was surprised to not see the 4" step down requirement in the IRC anymore (2006 edition). I had not read from any of the code committees that they were removing this age-old requirement. Don't know if it was removed by mistake and it will come back as an errata fix or whether it was really meant to be removed. I will write to the ICC to ask and find out why.

I still plan to build in that drop-down step to my plans. It has been a requirement for so long that I am hoping it was always done for a good reason and should not have been abandoned.

I would be cautious about building in a floor drain to the garage floor if that drain will tie into the sanitary waste system for the house. That sounds like it would not be approved by the plumbing code because of the possibility of oil and gas then mixing into the sanitary system. Also, most likely the trap in that floor drain will dry up because it won't receive enough water over a constant amount of time and that would then allow sewer vapors into the garage. Or, that drain will require a trap primer to keep it wet to stop vapors from coming back up the drain and into the garage and then that's another cost, maintenance item, and I suppose if the garage gets cold enough, the water in the trap could freeze. I think sloping the garage floor to get rid of any water that accumulates on the floor is still a cheap, sound, and proven way to handle that.

David,

Was the 4" step requirement in the 2003 IRC? If so what section was it in?

I totally agree about the floor drain. We typically slope the garage floor toward the door. For this particular plan the fire door into the house is located towards the front. The architect involved feels that using the drain and not having a 4" step allows the garage to be accessible. I found out his plan when I mentioned the garage couldn't accommodate the ramp due to the size of the garage and the location of the fire door. That's when he hit me with this.

Did a job in Arizona that referenced '03 IBC,IRC and IFC back in 2005.
The architect of record for this project also eliminated any step up into the house from the garage. This was new to me as well, but apparantly has been around since the '03 codes. What else threw me was a self-closer was not a requirement either. IMO a step or better yet a 6" curb is desireable, just for the fact that you can hose out the garage without worry of soaking the first floor. The only explanation I received from the plan reviewer/building official was it was no longer a requirement per code.
As a side note, the fire rating for garage/house roof and wall assemblies was changed at this time ('03).

I checked back as far as the 2000 IRC and the garage step-down had also been removed from it. Seems that when BOCA, UBC, and SBC all merged back just before 2000 and the IBC and IRC came into existence as the combined code of all 3 former code agencies, the garage step-down requirement disappeared and none of us (architects and builders) caught it because it had been a requirement for decades.

I did find in the 2000, 2003, and 2006 IRC's that section R309.3 still requires that garage floor slabs be sloped to the vehicular door for the "movement of liquids."

I too concur that it is much safer to have the garage down lower than the finished house floor so that when Joe weekend-warrior gets out the firehose to wash out the garage, the carpet or wood floors that are on the inside of the house surrounding the garage don't get trashed from water getting blown under the sill plate that is flush with the garage floor slab.

Hello David,

Thanks for checking on this. It's a surprise to me...

Another reason for the sloped floor that occurs up here: in the winter, melting snow/ice/sludge that has built up in the wheel wells, has a better chance of flowing out the door after it melts.

We just recently switched to using the garage as the accessible route. That allows us to have a step at the main entrance. Here in MN, that makes for a much better weather proofing situation at the front door. The flush threshold can be problematic with snow and water. And I too would be surprised if anyone allowed garage floor drains.

David,

Thanks for checking that far back, I appreciate it.

Ohio has customized the section on the garage slope to:

The area of the floor used for parking of automobiles or other vehicles shall be sloped to facilitate the movement of liquids to a drain or toward the main vehicle doorway.

I guess based on the original architect's recommendation and the findings here that I can raise this garage floor up and eliminate the step. Since this wil be built in Ohio it looks like I can just slope the floor to a drain and am good to go.

Thanks to everyone for posting and helping.

I have had 6 back and forth e-mails with the ICC on this item already this afternoon. They have now referred my question up to the guy in charge of the 2006 IRC code to see if he can answer why the step-down section is not in the IRC. Apparently, it has NEVER been in any of the IRC's since the first one published back in 2000. It had been in UBC, BOCA, SBC, and CABO prior to the existence of the ICC, IBC, and IRC and since these new codes were a merging of the former codes, I am surprised that the step-down reference was eliminated.

Maybe I opened up a hornet's nest with my question to them and maybe they will find an "oops" that someone forgot to type in that requirement when the IRC was developed. I will write back when I hear from the head honcho at the IRC on the history of why this section has vanished.

I certainly wouldn't put my name or seal on a garage without that 4" lip...regardless of the IRC. And I'm not sure I would for a handicapped entrance through a garage unless there was a 36" accessible "man-door" out of the garage on a path of egress. If you need the wheelchair, you certainly can't open the overhead garage sectional doors without assistance.

I prefer getting around the lack of a lip at the front door by using a PT wood boardwalk slightly elevated so that water can drain through the deck. This usually means a wood front porch rather than poured concrete patio. In a side-entry townhouse, this also solves the sidewalk crossing the drainge-swale issue by using the front porch as a bridge. Townhouses here typically do have basements, so the floor-elevation is already 18 to 24inches above the typical grade. And the rear patios also get replaced with slightly raised wood decks so the rear doors have a weather lip while the walking-surface is flush. We just make sure that the synthetic or composite decking "boards" have sharp-corners rather than the typical generous chamfers of PT lumber; that way the surface stays relatively smooth.

Handicapped and ADA's a bitch; and I'm glad I don't deal with it full-time like I did in my past architectural life doing multi-family.

I checked all the way back to the 1986 CABO code (the original ICC effort) and the requirement for a 4" lip was not there. It was, however, required by the Regional Dwelling Code (1966) which was very popular and widely adopted/adapted in northeastern Ohio and still used in some areas until 2006.

I, too, would not have less than a 4" lip or step at the opening into the living area and an 8" lip if there was a stairway to the basement open to the garage.

Daniel,

I think you may have uncorked the answer to this mystery with your mentioning of CABO. I too checked CABO to way back. You are right in that the step-down requirement was not in it, maybe ever. I also think that CABO, since it was already the combined 1 and 2 family dwelling code of UBC, BOCA, and SBCCI, simply became the IRC. Therefore, the IRC does not contain a requirement for the garage step-down.

I then looked up BOCA and the SBC. Seems that both, all the way up to the last one's published prior to the IBC taking over, DID have a required 4" step down for private, attached garages to residences. In the 1984 BOCA, it was section 608.1. I know in most jurisdictions in the northeast where I used to practice, they always used BOCA, even for houses. They did not use CABO. So, I grew up with the 4" step-down requirement and it stuck all the way up until the IBC and IRC came out in 2000.

Seems that the IBC, that was a merging of UBC, BOCA, and SBCCI, then purged the step-down requirement from the "private garage" section. I am guessing they did so in order for the IBC to better coordinate with the IRC since all building departments started just using the IRC and not the IBC for 1 and 2-family dwellings.

Good catch, David. It never dawned on me to look at BOCA, since here in Ohio BOCA was used solely for commercial and multifamily buildings. Prior to 2006, Ohio did not have a statewide residential code for 1, 2, & 3 family dwellings. Every jusidiction used their own, sometimes based on the whim of an otherwise, unemployable bother-in-law of the mayor.

Note: 3 family dwellings is an Ohio specific addition to the Ohioized IRC.