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Fire Separation Requirements for Barndominiums

Fire Separation Requirements for Barndominiums and Shouses

Loyal reader CHUCK in MERINO timed asking this question perfectly, as fire separation requirements for barndominiums, shouses and post frame houses had just made it to my list of subjects to research and comment upon.

Chuck writes:

“I was wondering if you could pen your interpretation of the construction details pertaining to the separation wall and/or sheetrock detail of each side of a shop and house all being under one roof?

I live in rural Logan County Colorado with no official construction inspection required (other than state electrical and plumbing). This is from the county website:

“Logan County has adopted the 2006 IBC building code and the 2006 Energy Conservation Code.  All new structures must be compliant with these codes. No building shall be erected, occupied, moved or structurally altered until a permit therefore has been issued by the Building Department.  Building Permits are required for roof repair or replacement”

Thank you Guru, you are the best!”

Good question, glad you asked and thank you for your kind words! I also appreciate clients who want to do things right, even when plan reviews do not exist and there are no inspections. Meeting Code requirements is a fire, life and safety issue.

I was always brought up believing it took 1/2″ drywall on the house side of a wall between garage and house and 5/8″ Type X on the garage side. If the garage side did not have a ceiling then drywall had to run up to the roof line. Even when I worked for a sheetrocker as a teen, this is how he did everything. All made sense to me.

Well Building Codes have their own ideas. If your shop (aka garage) is 1000 square feet or less, then it is classified as a “U” occupancy and these are requirements:

Garage to residence or attic – 1/2″ gypsum board on garage side

Gambrel HomeIf there is a habitable room above garage – 5/8″ Type X gypsum board on ceiling
Doors between garage and residence shall be 1-3/8″ minimum thick solid wood, solid or honeycomb-core steel doors not less than 1-3/8″ thick, or 20-minute fire-rated doors, equipped with a self-closing or automatic-closing device.

If your shop/garage is over 1000 square feet, is becomes an S-2 occupancy and fire separation requirements get tougher:

If equipped with an automatic sprinkler system one hour fire separation is required, if no sprinklers two hours. If the area (shop/garage) is used only for private or pleasure vehicles, then it can be reduced to one hour. 

I have run into this two-hour rating requirement before with a gambrel style barndominium, where our client was living upstairs and parking below. Because it “looked” like a barn, our client’s Building Official required two-hour separation. Walls and columns supporting this second floor also were required to meet two-hour requirements! No amount of debate was going to change this Building Officials’ mind either.

To achieve a one-hour rating would take a layer of 5/8″ Type X gypsum wallboard on each side of a wall, or two layers on a ceiling. A two-hour rating would double these requirements.

I personally like 5/8″ Type X and use it on walls and ceiling everywhere in our shouse. It lies much smoother than 1/2″, does not dent as easily, plus it affords added fire protections, with minimal added investment.

The Use and Occupancy Use Challenge

The Use and Occupancy Classification Challenge Part I
Every building, regardless of how it is constructed has a Use and Occupancy Classification (sometimes more than one).

In order to best enjoy this, you can play along at home by opening this free access link to the International Building Code (ICC): https://codes.iccsafe.org/public/document/IBC2015

Who Should Read This?
Post frame building contractors, building designers as well as anyone considering a building which will have mixed occupancies, or a single occupancy other than R or U should read through these IBC Code chapters so as to be able to make informed decisions as to the planning of their building. In the event your proposed building will be for any commercial use, it is best to get involved early in a pre-application conference (read more here: https://www.hansenpolebuildings.com/2013/01/pre-application-conference/).

Let’s play using an actual real life scenario.
Imagine this – a monitor style building which has a center portion 20 feet wide with a 20 foot eave height. The wings (enclosed sheds) off each side are 10 feet wide and slope from 13’4” to 10 feet (4/12 roof slope). The entire building is 112 feet in length. In the center section is a second floor which is 20 feet by 50 feet.

The square footage is 4480 on the main level and 1000 square feet on the second floor.
The building will initially be used as a barn, with the eventual intention of it being a wedding venue on the main level and having bedrooms on the second floor.

For those following along, go to Chapter 3 of the IBC.
Looking at the eventual use of the building as a wedding venue, it could be Assembly Group A:

“303.1 Assembly Group A.
Assembly Group A occupancy includes, among others, the use of a building or structure, or a portion thereof, for the gathering of persons for purposes such as civic, social or religious functions, recreation, food or drink consumption or awaiting transportation.”
In fact, i probably is a best fit as Assembly Group A-3.
Of course the building will also eventually have bedrooms. If the building was not a post frame building, and was all residential, it could fall under the auspices of the International Residential Code (IRC) which is a prescriptive code for stick framed housing.
“310.5 Residential Group R-3.
Residential Group R-3 occupancies where the occupants are primarily permanent in nature and not classified as Group R-1, R-2, R-4 or I, including:
Buildings that do not contain more than two dwelling units”

Of course there is also the initial use of the building, as a barn.

“UTILITY AND MISCELLANEOUS GROUP U
312.1 General.
Buildings and structures of an accessory character and miscellaneous structures not classified in any specific occupancy shall be constructed, equipped and maintained to conform to the requirements of this code commensurate with the fire and life hazard incidental to their occupancy. Group U shall include, but not be limited to, the following:
Agricultural buildings
Barns”
SECTION 420 of the IBC applies to R-3

In cases where you have mixed occupancy separation walls are required.

420.2 Separation walls.
Walls separating dwelling units in the same building, walls separating sleeping units in the same building and walls separating dwelling or sleeping units from other occupancies contiguous to them in the same building shall be constructed as fire partitions in accordance with Section 708.
420.3 Horizontal separation.
Floor assemblies separating dwelling units in the same buildings, floor assemblies separating sleeping units in the same building and floor assemblies separating dwelling or sleeping units from other occupancies contiguous to them in the same building shall be constructed as horizontal assemblies in accordance with Section 711.
[F] 420.5 Automatic sprinkler system.
Group R occupancies shall be equipped throughout with an automatic sprinkler system in accordance with Section 903.2.8.
Stay tuned tomorrow for Part II of Use and Occupancy.

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