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Garage distance separation from dwelling - Section R309

MarkRandall

MarkRandall

Silver Member
Joined
Dec 4, 2009
Messages
216
Location
Vancouver, Washington
Section R309.2 says garages less than 3 from a dwelling on the same lot require protection. So If I have a 3 foot total distance from dwelling to garage, there's no gypsum board protection required and I can have windows in either the garage or dwelling or both with no protection? Is that correct?

My code brain is trying to do the imaginary property line thing or look at connecting the two buildings, but if I'm reading this correct the garage can be as close as 3 feet and nothing is required. My client requested building an addition as close to an existing garage as possible. Before checking the code, I thought I might need 6' (3' each structure) with protection, 10' without any protection. I'm just totally surprised and decided to have you guys verify my code review.

R309.2.....Garages located less than 3 feet (914 mm) from a dwelling unit

on the same lot shall be protected with not less than 1/2-inch (12.7

mm) gypsum board applied to the interior side of exterior walls

that are within this area.
 
Re: Garage distance separation from dwelling - Section R309

MarkRandall said:
Section R309.2 says garages less than 3 from a dwelling on the same lot require protection. So If I have a 3 foot total distance from dwelling to garage, there's no gypsum board protection required and I can have windows in either the garage or dwelling or both with no protection? Is that correct?My code brain is trying to do the imaginary property line thing or look at connecting the two buildings, but if I'm reading this correct the garage can be as close as 3 feet and nothing is required. My client requested building an addition as close to an existing garage as possible. Before checking the code, I thought I might need 6' (3' each structure) with protection, 10' without any protection. I'm just totally surprised and decided to have you guys verify my code review.

R309.2.....Garages located less than 3 feet (914 mm) from a dwelling unit

on the same lot shall be protected with not less than 1/2-inch (12.7

mm) gypsum board applied to the interior side of exterior walls

that are within this area.
Click to expand...
Make it 3'-6" from the other building and be more safe that it is not going to be less then that distance. This would include the roof overhang projection should not be within 3'.

It does not say 3-ft. or less. Which is <=3'

It is < 3'

That mean if it is 3-ft. then you are ok. The same a law says that a building is non-exempt if over 4000 sq.ft. 4,000 sq.ft. is ok. If you don't want construction variability to bite you, make no portion including roof overhang projection (including gutter) to not project within 3'. So put a minimum of 3'-6" at roof overhang. Assume 24" overhang from wall to gutter for the projection for an ordinarily 18" roof overhang projection (not including 6" gutter). Therefore, you would want your wall to be 5'-6" to 6'-0" from the other building at roof overhang projection.

The portion that is within the projection zone would require that 1 hour type-x gypsum board fire wall rating and may need to meet the full 1hour rating all the way around the point of the wall and roof overhang join together. Even though the wall itself may be outside the 5' rating zone. Any door and door frame that projects into the zone would need to be 1 hour fire-rated assembly and the windows as well if it projects into the zone. However, the entire wall may not have to be 1hour fire rated.

Local conditions may amend this. I remember a 5-ft rule. I felt so lucky. :)

There is some variability with this and don't forget the fire marshal whom might require additional requirements and it goes because he is the fire marshal.
 
Re: Garage distance separation from dwelling - Section R309

Mark,

"there is no gypsum board protection required and I can have windows in either the garage or dwelling or both with no protection? Is that correct?"

Yes, according to the 2006 IRC R309. The 3' seems to cover it.

Uncle Bob
 
Re: Garage distance separation from dwelling - Section R309

Uncle Bob,

That's how I see it (I just don't believe it).

I would not interpret measuring from overhang. Any other comments on that?

I'll probably stay 5' back. The area where the two structure meet is only about 30" of wall length, but there is a window in the garage in that 30".
 
Re: Garage distance separation from dwelling - Section R309

MarkRandall said:
Uncle Bob,That's how I see it (I just don't believe it).

I would not interpret measuring from overhang. Any other comments on that?

I'll probably stay 5' back. The area where the two structure meet is only about 30" of wall length, but there is a window in the garage in that 30".
Click to expand...
Is this an attached or detached garage? If attached, then all that fire-rating would not be required even if attached by just a roof. Then the space inbetween is a breezeway and would be governed under another set of code sections.

Some thoughts? IIRC: It would then be one structure not two.

The reason I would start from overhang is there is other codes governing roof overhang fire protection that is within the 3-ft. separation. The whole idea is a complete 3' separation from ground to outer space between the two buildings if you don't want to install 1-hr or higher fire-rated walls and if the buildings comes within that then fire-rating would be required at any of the areas that are projecting within that 3-ft. space.

If the structure makes a complete connection then fire-rating is not required. Unless there is some state/local amendment.

I remember this a few years ago.
 
Re: Garage distance separation from dwelling - Section R309

"Is this an attached or detached garage?"

No, I wouldn't reference this code section if it was.

I initially was concerned IRC would require 10' separation (5' each) to do unprotected construction. I was preparing to get creative by thinking about attaching the two structures, but then I did the code research and came across the 3' requirement.

Actually, the more I think about it, it is not all that surprising. If attached the only requirement is gypsum boar on the garage side. 3' separation provides more protection than that.
 
Re: Garage distance separation from dwelling - Section R309

MarkRandall said:
"Is this an attached or detached garage?"No, I wouldn't reference this code section if it was.

I initially was concerned IRC would require 10' separation (5' each) to do unprotected construction. I was preparing to get creative by thinking about attaching the two structures, but then I did the code research and came across the 3' requirement.

Actually, the more I think about it, it is not all that surprising. If attached the only requirement is gypsum boar on the garage side. 3' separation provides more protection than that.
Click to expand...
Technically, if it is attached then fire-rating is no more required then the rest of the house and whatever gap would be a covered breezeway but the structure would be an addition versus a separate building. The 5-ft rule is in regards to two buildings within 5-ft. requires fire-rated walls. They are separate buildings if they are completely detached.

If attached, then the garage would just need to meet R309. It wouldn't need to be fire-rated level. If detached, it would depend on distance apart. You would need to look at Table R302.1 & R302.1.

Only 5-ft. separation for unprotected construction of two separate buildings.

EDIT: To remove "ORSC talk" for plain IRC 2006.
 
Re: Garage distance separation from dwelling - Section R309

Mark,

I may have missed something by consentrating on R309.2;

Look at R302.1 and Table R302.1

According to the Table; the "(not fire-resistance rated)" requires 5' separation for both the wall and projections.

:oops: Plan Approver be me to it.

Sorry,

Uncle Bob
 
Re: Garage distance separation from dwelling - Section R309

Uncle Bob said:
Mark,I may have missed something by consentrating on R309.2;

Look at R302.1 and Table R302.1

According to the Table; the "(not fire-resistance rated)" requires 5' separation for both the wall and projections.

:oops: Plan Approver be me to it.

Sorry,

Uncle Bob
Click to expand...
Depending on the code books in use.... In Oregon, it is 3' except for local amendments or Fire Marshal ruling. WA, I believe is plain IRC 2006 so it is 5-ft. unless amended.

If any projection is within the 5-ft zone then then those portions needs to be fire-rated. If roof projects within the 5-ft. the entire roof projection from wall to end of projection within the 5-ft separation distance would need to be fire-rated. Fire Marshal can be anal and have to entire roof projection on that wall face of the garage to be fire-rated.

Depending on how close the projection and wall is, I might tie the roof to the rest of the house even if it is 30" but I would obviously need to be sure the structure and tie is strongly tied together to resist seismic.

One of two things, the entire garage including roof projection is 5-ft or more from the house or I tie the roof system of the garage and house together if I don't want to have to meet that 1-hr. fire rating. Otherwise, bite the bullet and make it fire-rated.
 
Re: Garage distance separation from dwelling - Section R309

I see the 309.2 "3-ft." rule. If it was attached then that would apply unless you have something like a 3-ft.+ breezeway under the tied roof between the house and the garage portion.

That could be interesting for input.
 
Re: Garage distance separation from dwelling - Section R309

Plans Approver said:
Making a correction - be back soon. :D
Click to expand...
Unless completely attached which changes the rules a bit.
 
Re: Garage distance separation from dwelling - Section R309

R302.1 doesn't "jive" w/ R309.2.

Table R302.1 assumes that the overhang is 12" max. as stated in R302.1 for a 5' FSD. If your overhang is greater than 12" on either structure then the separation distance to maintain a nonfire-resistance rating on the overhang must be increased.

R309.2 only applies to walls less than 3' - what about walls over 3' away. That is where - IMHO - R302.1 - takes over. Then as in your original post you lay down an imaginary line between the 2 structures and find the location that works best for you or ask your local AHJ.

R302 seems to get changed every code cycle - 2003 it was call "Location on Lot" - 2006 "Exterior Wall Location" - 2009 "Fire-Resistant Construction". The wording to 2006 R309.2 disappears in 2009.
 
Re: Garage distance separation from dwelling - Section R309

Dan,

Changng every cycle; you gotta love the ICC. :)

I think that is why a lot a AHJs stay with a code adoption for 9 years and more; when they can.

Uncle Bob
 
Re: Garage distance separation from dwelling - Section R309

"Changng every cycle; you gotta love the ICC. :) "

I wish we could keep a code for a period longer than 3 years. From 1966 (I was alive, but not not of code age) to 1992 we used what was called the "Regional Dwelling Code" about 150 pages and the BO was the otherwise unemployable bother-in-law of the mayor. From 1992 on it was either the CABO or ICC code every 3 years until the state imposed a statewide residential building code. Local ammendments only by permission of the state and then incorporated statewide. That caused a great increase in the size of local zoning codes which now means former building code regulations are enforced by the zoning appeals board. We will be getting 2009 IRC in 2011 originally scheduled for 2010.
 
Re: Garage distance separation from dwelling - Section R309

Uncle Bob said:
Dan,Changng every cycle; you gotta love the ICC. :)

I think that is why a lot a AHJs stay with a code adoption for 9 years and more; when they can.

Uncle Bob
Click to expand...
Yeah and then throw in local/state amendments....... then you feel like :?

Look at Oregon.... they even rename the code as well as amend it and then the local jurisdictions may amend it through local ordinances. Got to love it.
 
Re: Garage distance separation from dwelling - Section R309

Maybe I'm misreading the code (that's why I posted).

R302.1 and Table R302.1 is exactly where I started my code research and I understand that section. Later, though, in section R309.2 is lists a more specific condition of separation between a dwelling and a garage on the same property. That condition is not referenced in 302, so wouldn't 309.2 take precedence over any of the other conditions that I now assume refer to property line separation, not separation between a dwelling and a garage on the same property. If 309.2 doesn't apply, what exactly is it saying then.

I didn't know 309.2 even existed until today (haven't done much residential since I-codes came out). I'm trying to understand intent and if you take all those sections together, 309.2 would not make any sense unless you interpret it superceding the info in 302.
 
Re: Garage distance separation from dwelling - Section R309

R102.4 Referenced codes and standards. The codes and

standards referenced in this code shall be considered part of the

requirements of this code to the prescribed extent of each such

reference. Where differences occur between provisions of this

code and referenced codes and standards, the provisions of this

code shall apply.

Exception: Where enforcement of a code provision would

violate the conditions of the listing of the equipment or

appliance, the conditions of the listing and manufacturer's

instructions shall apply.

The code with the stricter / higher requirement wins.

IIRC: 1-hour fire rated wall would be required on BOTH sides of the wall and 1-hr fire rated gypsum board is 5/8" Type X Gypsum board. 309.2 primary would apply most likely if the garage was attached and is within 3-ft. of the house. Unless it impacts walls perpendicular to the fire separation line. That is about my guess of its applicability.

It (309.2)would not really apply much if the garage was attached with a common roof with a minimum of 3-ft. Breezeway inbetween the garage exterior wall faces and the house.
 
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
 
Re: Garage distance separation from dwelling - Section R309

Thanks All for all the input.

The whole purpose of this discussion was to try and make sense of R309.2 as it didn't make sense to me. I guess since they are pulling that verbage out of the 2009 version, it was not making sense to a lot of people. I may look at attaching the two structures as that will allow the requested addition size with the least requirements.
 
Warning Rant

In their infinite wisdom, ICC changed around all the building planning requirements related to lot line proximity in 2006.

Previously, fire separation was measured between buildings which allowed traditional zero lot line type development.

But despite any significant evidence that such development poses a hazard, IRC 2006 changed to fire separation based on distance from lot lines.

It was change for the sake of change.

I'm not surprised that 2009 has to clean up the mess.

--end rant
 
Re: Garage distance separation from dwelling - Section R309

R309.2 is less restrictive and should be considered an exception to R302.1 & Table R302.1.

At 3' or less R309.2 allows 1/2" gyp. on the interior of the exterior walls and permits a solid door or etc. Whereas, at less than 5 feet, Table R302.1 requires 1 hour from both sides on both walls, none or some (25%) openings, and 1 hour overhangs.

The way I see your situation is that you will need 10' between the detached garage and the proposed addition in order to have unprotected walls, overhangs and openings. If the overhangs are over 2' then the overhangs would need 1 hour.

Again, your local AHJ may see it differently.
 
Re: Garage distance separation from dwelling - Section R309

In their infinite wisdom, ICC changed around all the building planning requirements related to lot line proximity in 2006.Previously, fire separation was measured between buildings which allowed traditional zero lot line type development.

But despite any significant evidence that such development poses a hazard, IRC 2006 changed to fire separation based on distance from lot lines.

It was change for the sake of change.

I'm not surprised that 2009 has to clean up the mess.
Click to expand...
It is popular for many to say ICC stands for International Cash Cow. I prefer that ICC stands for International Code Camel as in "A camel looks like a horse that was planned by a committee." Can't wait for the changes in the Green Building Code and future cap and trade changes. The camel will look sane, logical, well thought out.

-- end rant 2.0
 
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