Garage distance separation from dwelling - Section R309

[JBI]

Re: Garage distance separation from dwelling - Section R309

The camel is the preferred mode of transportation in the desert for many good reasons, none of which include anything to do with building construction...

RickA - "...and 1-hr fire rated gypsum board is 5/8" Type X Gypsum board..." In what reality?

There are many listed 1 hr assemblies that use 1/2" plain GWB.

Individual components are not generally assigned a fire-rating, and 5/8" GWB in and of itself does not carry a 1 hour rating.

 

[brudgers]

Re: Garage distance separation from dwelling - Section R309

The camel is the preferred mode of transportation in the desert for many good reasons, none of which include anything to do with building construction...RickA - "...and 1-hr fire rated gypsum board is 5/8" Type X Gypsum board..." In what reality?

There are many listed 1 hr assemblies that use 1/2" plain GWB.

Individual components are not generally assigned a fire-rating, and 5/8" GWB in and of itself does not carry a 1 hour rating.

Cows have the same number of legs as a camel and can legally provide transportation in exempt deserts. The code doesn't require a desert to be dry and a cow is a trasportation professional.

 

[JBI]

Re: Garage distance separation from dwelling - Section R309

brudgers - Was that humor? :lol: :lol:

 

[brudgers]

Re: Garage distance separation from dwelling - Section R309

Sarcasm.

 

[JBI]

Re: Garage distance separation from dwelling - Section R309

Close enough!

 

[brudgers]

Re: Garage distance separation from dwelling - Section R309

Close enough!

For government work.

 

[RickAstoria]

Re: Garage distance separation from dwelling - Section R309

Mark,In the 2006 IRC; R309 only address attached garages and detached garages (R309.2), "less than" 3' from the residence, (and is more restrictive).

It does not address detached garages 3' or more from the residence.

The requirement for detached garages "less than" 3'; in R309.2, was added to the 2006 IRC (as indicated by the solid black line on the side); and according to Dan, was removed in the 2009 IRC; probably because of the confusion it caused.

(It evidently "leaves the impression" that detached garages 3' and more do not require separation protection; and that's why it was taken back out of that section.)

I agree with Dan; R302 applies to all detached garages 3' and more from the residence "in the 2006 IRC".

Hope this helps,

Uncle Bob

R302 requires 1 hour fire-rated walls and that is 5/8" Type X gypsum board on both sides of walls parallel with the fire-separation line (which is 5-ft from the house) if IIRC.

R309.2 requires 1/2" on the inside portion of interior walls within 3-ft.

Maybe for example, if the garage wall is 1-ft from the house. That it would require 5/8" Type-X on walls parallel to the fire separation line and 1/2" for all other interior walls of the garage within 3'. So, in technical regards, for walls within 5-ft from house parallel with fire separation line shall have 5/8" protection on BOTH sides. While walls non-parallel to fire separation line within 3-ft of the other building or rest of the house shall be a minimum of 1/2". Other walls maybe 3/8" or 1/4". Anyway, R309.2 seems to be somewhat moot. It maybe stricter in portions but the truth of the matter, both R302 and R390.2 shall be complied. Fire-rated wall protection on walls parallel to the fire separation line within 5-ft. shall be 5/8" Type X Gypsum board on BOTH sides (If I remember that correctly (on exterior - minimum of 1 hr. fire rated brick can be used in lieu of gypsum board). Other walls within 3-ft. shall be a minimum of 1/2". That would be my interpretation of it.

 

[RickAstoria]

Re: Garage distance separation from dwelling - Section R309

The camel is the preferred mode of transportation in the desert for many good reasons, none of which include anything to do with building construction...RickA - "...and 1-hr fire rated gypsum board is 5/8" Type X Gypsum board..." In what reality?

There are many listed 1 hr assemblies that use 1/2" plain GWB.

Individual components are not generally assigned a fire-rating, and 5/8" GWB in and of itself does not carry a 1 hour rating.

Ok, if it has the assembly approval and approved by B.O. as an alternative then ok. The code specifies 5/8" that meets 1 hour fire rating. I'm pointing from code but yes alternative products that meets that 1 hr rating can also be used. Call it alternative method/product as approved by B.O.

 

[Plans Approver]

Re: Garage distance separation from dwelling - Section R309

"The code specifies 5/8" that meets 1 hour fire rating."

Hey Rick,

Where? Is that at your local or state level? I couldn't find it in the 06 IRC. Are you stating exceptions, trade-offs, or membranes in lieu of assemblies?

 

[JBI]

Re: Garage distance separation from dwelling - Section R309

Nah. He's just misapplying the allowance for 5/8" type x garage side only for attached garages.

 

[brudgers]

Re: Garage distance separation from dwelling - Section R309

Practically speaking 5/8" type X will provide one hour of fire protection when used in a vertical assembly such as a wall or column wrap.

That's why you can get a 1 hour rated wall with 2 1/2" metal studs despite the thermal bridging.

The wood framed calculated assemblies in the code include horizontal applications as well.

That's why it's per layer value is only 40 minutes.

Of course, none of this is a substitution for code requirements or listed assemblies.

 

[RickAstoria]

Re: Garage distance separation from dwelling - Section R309

Nah. He's just misapplying the allowance for 5/8" type x garage side only for attached garages.

If attached then fire-rating not required. If detached then it must be on both sides. I'll double check what I wrote if I was typing too slow for my thinking and got erroneous.

R302 pertains to detached garages not attached. R309 can apply to attached and detached garages. Code default for 1-hour fire rated wall is 5/8" Type X gypsum board. Of course rated assemblies may be used in lieu of the gypsum board.

Since 5/8" is thicker and therefore more strict then 1/2" - it would apply for all walls parallel to the fire separation line and is within 5-ft. For any other wall within 3-ft of the main residence on a detached garage would need to be 1/2" for any portions within 3-ft.

Regarding attached garages, the any wall within 3-ft of the rest of the house would need a minimum of 1/2". On detached garages, R309.2 would apply also to walls perpendicular to the fire separation line. That is how I would interpret it as minimum but walls parallel to fire separation line would be 5/8" Type X GWB within 5-ft. or equivalent or higher rated assembly.

I would expect 5/8" Type x GWB (or equivalent or higher rated wall assembly) on walls parallel to house walls within 5-ft. on detached garages and 1/2" on other walls for portions within 3-ft. of house on a detached garage. That would be my interpretation if I was a code inspector.

If i see 1/2" instead of 5/8" then I want to see the rating and will check if assembly was installed according to manf. specs.

 

[georgia plans exam]

Re: Garage distance separation from dwelling - Section R309

Here is how I see it.

Section R309.2 has specific requirements for a detached garage wall which is less than 3’ from the house. If it is more than 3’ from the house, no protection is required. The imaginary line between two buildings on the same lot is from the IBC and is not a part of the IRC.

If, however, the back or side wall is within 5’ of the property line, Section 302.1 and Table 302.1 would apply to that wall.

GPE

 

[EPrice]

Re: Garage distance separation from dwelling - Section R309

...The imaginary line between two buildings on the same lot is from the IBC and is not a part of the IRC...

The imaginary line language can be found in the IRC in the definition of "Fire Separation Distance"

 

[EPrice]

Re: Garage distance separation from dwelling - Section R309

After listening to both sides of the discussion, my opinion is that in the case of detached garages, R309 trumps R302. R302 is a general requirement, while R309 is a specific requirement intended for garages and carports. To interpret it otherwise leads to scenarios that do not make sense. If we say that R302 applies to garages that are more than 3' from the house, then for garages that are 0' to 3' from the house, the only requirement is for 1/2" gypsum on the inside face of the garage wall, but if the garage is 3'-1" away from the house then one or both of the walls is required to have a layer of 5/8" gypsum on each face, depending on where the imaginary line is drawn. How does that make sense?

 

[georgia plans exam]

Re: Garage distance separation from dwelling - Section R309

Good point. I missed that.

Still, I believe that the specific requirements of Section R309.2 trump the requirements of 302.1.

GPE

 

[fw.]

Re: Garage distance separation from dwelling - Section R309

Section 302 has nothing to do with Section 309. 302 has to do with lot lines, 309 is about garages on the same lot. If the garage was placed less than 3 feet away from the dwelling the window couldn't be there, at 3 feet no problem. Section 309 is silent about projections, but it only requires the sheetrock on the interior of the wall. It doesn't say that if closer than 3 feet you need to do more. The code is a minimum, don't overthink it. If it was my home I might do something different, but I enforce the code.

 

[TJacobs]

Re: Garage distance separation from dwelling - Section R309

Here is how I see it.Section R309.2 has specific requirements for a detached garage wall which is less than 3’ from the house. If it is more than 3’ from the house, no protection is required. The imaginary line between two buildings on the same lot is from the IBC and is not a part of the IRC.

If, however, the back or side wall is within 5’ of the property line, Section 302.1 and Table 302.1 would apply to that wall.

GPE

See definition of fire separation distance below to see it is also in IRC, not just IBC.

My take is that 302.1 is used for exterior walls of dwelling units and accessory buildings, including the fire separation distance between a detached garage and another building on the same lot or an adjacent lot. However, 309.2 applies to the protection required for a detached garage on the same lot as the associated dwelling unit. 309.2 modifies 302.1 for a detached garage only on the same lot as the dwelling unit.

I'd rather see that "exception" in 309.2 moved to 302.1 as an exception, with a pointer sentence in 309.2 to reference 302.1.

2006 IRC definition:

FIRE SEPARATION DISTANCE. The distance measured from the building face to one of the following:

1. To the closest interior lot line; or

2. To the centerline of a street, an alley or public way; or

3. To an imaginary line between two buildings on the lot.

The distance shall be measured at a right angle from the face of the wall.

 

[JBI]

Re: Garage distance separation from dwelling - Section R309

IRC 2006

SECTION R302 EXTERIOR WALL LOCATION

R302.1 Exterior walls.

Construction, projections, openings and penetrations of exterior walls of dwellings and accessory buildings shall comply with Table R302.1. These provisions shall not apply to walls, projections, openings or penetrations in walls that are perpendicular to the line used to determine the fire separation distance. Projections beyond the exterior wall shall not extend more than 12 inches (305 mm) into the areas where openings are prohibited.

Exceptions:

1. Detached tool sheds and storage sheds, playhouses and similar structures exempted from permits are not required to provide wall protection based on location on the lot. Projections beyond the exterior wall shall not extend over the lot line.

2. Detached garages accessory to a dwelling located within 2 feet (610 mm) of a lot line are permitted to have roof eave projections not exceeding 4 inches (102 mm).

3. Foundation vents installed in compliance with this code are permitted.

SECTION R309 GARAGES AND CARPORTS

R309.2 Separation required.

The garage shall be separated from the residence and its attic area by not less than ½-inch (12.7 mm) gypsum board applied to the garage side. Garages beneath habitable rooms shall be separated from all habitable rooms above by not less than 5/8-inch (15.9 mm) Type X gypsum board or equivalent. Where the separation is a floor-ceiling assembly, the structure supporting the separation shall also be protected by not less than 1/2-inch (12.7 mm) gypsum board or equivalent. Garages located less than 3 feet (914 mm) from a dwelling unit on the same lot shall be protected with not less than ½-inch (12.7 mm) gypsum board applied to the interior side of exterior walls that are within this area. Openings in these walls shall be regulated by Section R309.1. This provision does not apply to garage walls that are perpendicular to the adjacent dwelling unit wall.

I'm not sure I understand the confusion.

And for the record, unless I am missing something, the only place 5/8" Type X gypsum board is required is ceilings of garages with habitable space above with no reference to hourly rating of assemblies... :roll:

 

[FredK]

Re: Garage distance separation from dwelling - Section R309

Can't believe this is 5 pages . JD's post is right on the mark.

More things to worry about than 3'0" inches and less than 3'0"difference.

 

[Uncle Bob]

Re: Garage distance separation from dwelling - Section R309

John,

Thanks for straightening that out, I see I was more part of the problem than the solution.

Uncle Bob

 

[RickAstoria]

Re: Garage distance separation from dwelling - Section R309

Section 302 has nothing to do with Section 309. 302 has to do with lot lines, 309 is about garages on the same lot. If the garage was placed less than 3 feet away from the dwelling the window couldn't be there, at 3 feet no problem. Section 309 is silent about projections, but it only requires the sheetrock on the interior of the wall. It doesn't say that if closer than 3 feet you need to do more. The code is a minimum, don't overthink it. If it was my home I might do something different, but I enforce the code.

R302 has has nothing to do with lot line but can apply when there is a lot line issue but then zoning setbacks comes into the game. R302 has to do with two separate buildings within X number of feet from each other.

R309 makes provisions that addresses walls perpendicular to the fire separation line. The line being discussed is about the fire separation NOT lot separation.

So if you read it 302 applies to walls of buildings being constructed and work being done on existing buildings where the walls of two buildings are within 5-ft. Crossing the 5-ft. fire separation line which is the distance unprotected walls of two separate buildings can be to each other. Otherwise 1-hour fire protection must be achieved on walls that are not perpendicular or substantially parallel. Walls that are near perpendicular may be treated as perpendicular. Walls that are substantially parallel would be treated parallel. That is my interpretation.

This applies to walls NOT perpendicular (or substantially) to fire separation line.

309 applies to all interior walls of garages within 3-ft. of another building (or main residence) regardless of whether it is attached or detached.

 

[TJacobs]

Re: Garage distance separation from dwelling - Section R309

Section 302 has nothing to do with Section 309. 302 has to do with lot lines, 309 is about garages on the same lot. If the garage was placed less than 3 feet away from the dwelling the window couldn't be there, at 3 feet no problem. Section 309 is silent about projections, but it only requires the sheetrock on the interior of the wall. It doesn't say that if closer than 3 feet you need to do more. The code is a minimum, don't overthink it. If it was my home I might do something different, but I enforce the code.

R302 has has nothing to do with lot line but can apply when there is a lot line issue but then zoning setbacks comes into the game. R302 has to do with two separate buildings within X number of feet from each other.

Incorrect. Please reread the definition of fire separation distance, then reread 302. Lot lines is in there.

R309 makes provisions that addresses walls perpendicular to the fire separation line. The line being discussed is about the fire separation NOT lot separation. So if you read it 302 applies to walls of buildings being constructed and work being done on existing buildings where the walls of two buildings are within 5-ft. Crossing the 5-ft. fire separation line which is the distance unprotected walls of two separate buildings can be to each other. Otherwise 1-hour fire protection must be achieved on walls that are not perpendicular or substantially parallel. Walls that are near perpendicular may be treated as perpendicular. Walls that are substantially parallel would be treated parallel. That is my interpretation.

This applies to walls NOT perpendicular (or substantially) to fire separation line.

Not sure where you are coming up with some of this...

http://www.merriam-webster.com/dictionary/perpendicular

1 a : standing at right angles to the plane of the horizon : exactly upright b : being at right angles to a given line or plane

http://www.merriam-webster.com/dictionary/right%20angle

: the angle bounded by two lines perpendicular to each other : an angle of 90° or 1?2 ? radians

309 applies to all interior walls of garages within 3-ft. of another building (or main residence) regardless of whether it is attached or detached.

The garage has to be on the same lot as the dwelling unit and the garage has to serve that dwelling unit to use 309.

If you had a townhouse project, would you not reference 302 regarding rated walls between adjacent garages serving different units whether a lot line is involved or not?

 

[Plans Approver]

Re: Garage distance separation from dwelling - Section R309

This thread is suffering from length. So for my last say on it. I decided to post the commentary for 302.1 and 309.2. You can make your own decision on what you want to enforce in your jurisdiction. Since you may be able to make your own interpretations, just make a decision that your feel comfortable with and that will keep your residents safe. Make that decision available to any one wishing to build, add, remodel, etc. so that everyone is reading from the same script.

From the IRC Commentary for 302.1 This section provides details for issues related to building location on the property, including the fire rating of exterior walls, permitted openings and projections. Table R302.1 is a tabular overview of the requirements of this section.

Concerning exterior wall protection, the IRC assumes that an owner has no control over an adjoining property. Thus, the location of buildings on the owner's property relative to the property line requires regulation. In addition, Section R309, which lists the separation requirements for garages and carports, specifically requires garages located less than 3 feet (914 mm) from a dwelling unit on the same lot to have not less than 1/2-inch (12.7 mm) gypsum board applied to the interior side of the walls. Opening protection for these walls is regulated by Section R309.1.

The property line concept is a convenient means of protecting one building from another as far as exposure is concerned. Exposure is the potential for heat to be transmitted from one building to another during a fire in the exposing building. Radiation is the primary means of heat transfer.

Walls less than 5 feet (1525 mm) from the property line must be of 1-hour fire-resistant construction. The fire-resistance rating also requires the rating exposure to be for both sides. Specific provisions are not found in the IRC for the fire-resistance ratings of walls or other elements, so one may use either the IBC or another manual of fire-resistant assemblies. Projections may not be closer than 4 feet (1219 mm) to the lot line. Projections should not extend more than 12 inches (305 mm) into an area where walls are required to be of 1-hour fire-resistant construction must be protected on the underside with 1-hour fire-resistant construction [see Commentary Figure R302.1(1)].

Unlike the IBC, the IRC does not set a distance from the property line at which openings must be protected. Openings are not permitted in exterior walls where the exterior wall has a fire-separation distance of less than 3 feet (914 mm) from the lot line. Openings in a wall located at a distance in excess of 3 feet (914 mm) from the lot line can not exceed 25 percent of the maximum wall area (see Commentary Figures R302.1(2) and (3)]. Openings, projections or penetrations that are 90 degrees (1.57 rad) (perpendicular) to the line used to determine fire separation distance are not prohibited. Section R317.3 describes through penetrations and membrane penetrations in detail.

See the definition of Fire Separation Distance in Chapter 2. The requirements for protection do not apply to walls that are at a right angle (perpendicular to) the property line (see Commentary Figures R302.1(2) and (3)].

From the IRC Commentary for 309.2 Numerous potential hazards exist within garages because occupants of dwelling units tend to store a variety of hazardous materials there. Along with this and the potential for carbon monoxide build-up within the garage, the IRC requires that the garage be separated from the dwelling unit and the attic with at least 1/2-inch (12.7 mm) gypsum board or other equivalent material. If a habitable room is above the garage, the separation must be at least 5/8-inch (15.9 mm) Type X gypsum board or equivalent. In addition, garages located less than 3 feet (305 mm) from an adjacent structure must be protected with at least 1/2 inch (12.7 mm) gypsum board applied to the interior side of the garage. See Section R302. The close proximity to adjacent structures requires the additional protection.

There are two primary reasons for the enhanced fire endurance of a garage ceiling located beneath a habitable room. First, a fire occurring in a garage may well go undetected for an extended period prior to activation of a detector or other visual alerting. Second, the inherent fire load and hazardous household activities associated with a garage necessitate this additional level of protection if fire suppression forces are to have a reasonable opportunity to contain a garage fire to the area of origin. The single layer of 5/8-inch (15.9 mm) Type X gypsum at the garage ceiling increases the fire endurance of the assembly considerably, from 15 minutes for a 1/2-inch (12.7 mm) layer, to at least 40 minutes, or a 167 percent increase in endurance. When added to the rating for floor joists and certain subflooring combinations, the final endurance is close to 1 hour.

Additionally, the exterior walls of the garage are required to have 1/2-inch (12.7 mm) gypsum board on the interior face where they support floors separating all or part of a dwelling unit above the garage. Commentary Figure R309.2 shows two locations of gypsum wallboard; each achieves the protection required by the code.

Over and out.