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Help with 1 hour firewall

platymapus's picture

I need to find the definition of a residential 1 hour firewall.  The wall in question is in a detached garage that is within 3 feet of the side yard property line.  I've install 5/8" fire-rated drywall on both sides of the studs w/ blocking b/w the joist.  The inspector says I need to tape and bed the wall to complete the 1 hour rating.  I've built this wall w/o tape and bed over 100 times and now they have are saying that's not correct.


 


The head building inspector says they don't have anything that states tape and bed is necessary and said I need to show them something that is UL approved that doesn’t show tape and bed.


 


Thanks for your help.


 


 Trace

(post #102079, reply #1 of 26)

   Sorry, can't help.  Around here any rated wall has to be "fire taped". One coat tape and spackle. Any gaps at the edges sealed too...Buic


 

(post #102079, reply #2 of 26)

Your building codes are gonna define what THEY think is a one hour wall.

Doesn't really matter what you can pull off the internet - It's still up to them.

Bumpersticker: Nuke the Whales.

(post #102079, reply #3 of 26)

Where I was a builder in CA you had to tape and mud the joints to comply.

(post #102079, reply #4 of 26)

I don't know what literature you have around for USG (United States Gypsum Co.), but they have been a good resourse if you want to research some pretty standard UL approved fire seperation partitions. They have various partition details showing wood studs and steel studs or whatever best suits your particular needs. Give that a try, look them up online.

(post #102079, reply #5 of 26)

Here, I did a little leg work for you

Go to:

http://www.usg.com:80/navigate.do?resource=/USG_Marketing_Content/usg.com/web_files/resources/architects/Gypsum_Architectural_Reference_Library.htm

The architectural reference library has many goodies you may look for in the future, like acoustical seperations, fire seperations, aesthetic assemblies, etc. This can be a very useful tool for you.

For your purposes, look into the link for fire-resistant assemblies (sa-100)

Hope that helps.
Andrew

(post #102079, reply #6 of 26)

BTW, I could be wrong, but I don't think it is oficially a fire assembly without the proper mud, tape, and caulking, but maybe in your research you can proove me wrong.

Just because youve done something (100) times, does not make it right.

(post #102079, reply #7 of 26)

Im a past building inspector.


Im having a little problem understanding your post .


You say that you installed drywall on both sides of the walls?


First let me say that the protection needs to contain a fire inside so the protection needs to be installed there and not out side. Its useless on the out side unless its metal studs and even then its not the idea behind it .


One of the leading causes of house fires are  caused from fires started in the garage from fuel types. So then you are trying to save the structure from the inside.


Brick is an exellent idea on the out side and cement siding .


If the inspector will look it up fire taping and caulking is in the fire code sections and not the building sections.


5/8s fire code drywall has a 30 minute per layer rating . 2 sheets doubled of course provide the hour rating.


If the garage is detached Im a little confused why the hour rating .


For example ; When an attached garage is built , then the ajoinging wall to the house and the ceiling is suposed to be 1 hour but not any wall not contacting the the living space areas. .


On a 2 hour rating used in commercial the first 4 ft of ajacent walls have to be rated as same for flare reasons. Thats not listed in residential.


Tim



Memphest 2006


November 18th


Edited 9/7/2006 2:36 pm by Mooney


Edited 9/7/2006 2:39 pm by Mooney

 

(post #102079, reply #8 of 26)

Tim,
I think the need for the fire seperation lies in the fact that the proposed structure is less than 3 feet from the adjacent property. I forget where to site in the code off hand, and I'm in Massachusetts, but I know I have run into similar situations in the past with urban type buildings that were very close to property lines

(post #102079, reply #9 of 26)

Well he never stated how close it was.


I got to thinking the code I enforced has changed to another one here and I dont have it . So Im obsolete at best  along with every thing else about me . <G>


When I was practiceing the codes I could whupum out here but theres not anything left to whup out which reminds me of other things.


 


Tim


Memphest 2006


November 18th

 

(post #102079, reply #16 of 26)

 


Well sure he did.


"I need to find the definition of a residential 1 hour firewall.  The wall in question is in a detached garage that is within 3 feet of the side yard property line.  I've install 5/8" fire-rated drywall on both sides of the studs w/ blocking b/w the joist. "


how do you think xosder11 knew  :)

                                                 

(post #102079, reply #17 of 26)

Stated with in three feet of the sideline yard property line , not his house .


I still dont understand drywall on both sides . Its not a 1 hour wall . Drywall is not exterior material.


So what good is it ?


Tim


 


Memphest 2006


November 18th

 

(post #102079, reply #18 of 26)

There is sheathing-grade drywall, which I'd be tempted to use in this case.

The drywall on the exterior will keep the framing from catching fire, presumably, if exposed to a fire in the adjacent structure.


If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #102079, reply #19 of 26)

Then it needs to be a 2 hour wall since he doesnt have brick or concrete siding .  


Tim


Memphest 2006


November 18th

 

(post #102079, reply #20 of 26)

My recollection is that the OP's situation is that this wall is near a garage on his property. I suspect that, in at least some jurisdictions, that situation requires less protection than a wall near another property.


If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #102079, reply #21 of 26)

But he is using conrete siding

 

 


Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #102079, reply #24 of 26)

Thanks , IM gonna have to read a little better. <G>


:"FYI:  The wall consisted of a layer of 5/8" fire-rated drywall on each side of the stud w/ cement siding on the exterior.  This is required because I'm within 3 feet of the side yard property line."


Still no exterior drywall.


Tim


Memphest 2006


November 18th

 

(post #102079, reply #25 of 26)

There is drywall on EACH side of the stud. That places one layer on the exterior.

Are you argueing that it may not be RATED for exterior use?

 

 


Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #102079, reply #26 of 26)

didnt sound like it


 



Memphest 2006


November 18th


Edited 9/11/2006 9:38 pm by Mooney

 

(post #102079, reply #22 of 26)

Tim,

Does fiber cement (e.g. - Hardi) qualify the assembly any? I think the OP is using FC over the gypsum sheathing.

Bill

(post #102079, reply #23 of 26)

Yes, concrete siding is considered masonary. I know that sounds like a redundant statement but the codes will give allowances for a masonary wall as well as insurance.


The 4x8 sheets carry a 1 hour rating by its self . Of course its never by its self.


Any fire retardant sheeting would extend it .  


Anyway, my point being is that he only has a 30 minute interior wall rating. So it depends on what we are protecting.


To my calcs , he has a 1 1/2 hour exterior.


Tim


Memphest 2006


November 18th

 

(post #102079, reply #10 of 26)

Thanks for everyone’s help.  I found a building official who would take the time and help me research the issue.  Tape and bed is required.  All of this time I wasn't trying to break the rules, I just didn't know, 10 plus years and no red tag.


Every couple of years they spring something new on me and I'll call them on it, sometimes I'm right and sometimes they are right.


FYI:  The wall consisted of a layer of 5/8" fire-rated drywall on each side of the stud w/ cement siding on the exterior.  This is required because I'm within 3 feet of the side yard property line.


Thanks again.


 


 

(post #102079, reply #11 of 26)

I'd like to give a little "primer" on firewalls, and how they get their ratings.

The ratings are based upon actual full-size fire tests. A test panel, maybe 12 ft. square. is subjected to a massive natural gas flame for the specified time. Temperatures are measured on bot sides of the wall. (On the fire side, to adjust the size of the fire to a 'standard' pattern, and on the 'protected' side to see if enough heat gets through to ignite stuff on that side).
If the wall is a "bearing" wall, the appropriate load is evenly applied, and monitored, using hydraulic cylinders.
Sometimes, at the end of the test, the assembly is subjected to a stream of water from a fire hose.

A key thing to remember is that an "assembly" is tested, and not just individual components. For example, a particular door / frame assembly is installed in a particular type of wall. You must make a similar assembly to have the rating. It is perfectly possible that a door assembly from one wall type will fail if used on a different wall type.

In general, two things must not happen, for the wall to pass. First, the wall may not fall apart, or burn through. The wall might be bowed, twisted, and completely trashed... you might be able to tear it apart with your hands... but it simply has to "be there."

The second part is less obvious: the protected face cannot get too hot, anywhere. The wall does little good if the heat passes through. A wall made of plate steel might not "burn" at all, but it has very little value as a fire wall.

This is why you can be sure that every wall design that has nails or screws is going to have some thermocouples mounted directly over them during the test. It does no good if the exposed heads themselves start a fire on the protected side! So, every test I saw had something.... usually gypsum and tape... over the fasteners. Walls with multiple layers of drywall had seams offset, and layers 'fire-taped,' just to make sure. Again, I guarantee every joint or seam has a thermocouple over it!

This issue of heat transmission is also one of the reasons there is absolutely NO difference between the performance of light steel studs, and wood studs, in fire ratings. Sure, the steel "doesn't burn," but it also transmits heat to the drywall quite well.
As a side note, in these tests, wood studs don't really "burn" either. Rather, they slowly char through. As they char, the remaining wood actually acts as an insulation protecting that part of the wall from heat!
End result: changing from wood studs to light steel has NO effect on the test performance. This is true, whether the wall is bearing, or not.

There are listed assemblies that have the drywall on only one face of the wall. For example, two layers of 5/8 drywall, on one face of the wall only, has exactly the same rating as a wall with one layer one each side. The difference is only that the wall faced on both sides is listed for fire exposure to either side.... while the open wall is rated for exposure to the covered side only.

Absent your being able to document an assembly passing the ASTM test, with uncovered fasteners, you'll have to cover them to comply. UL publishes a "Fire Resistance Directory" with thousands of wall designs in it. There are others out there as well. Good hunting!

(post #102079, reply #12 of 26)

The idea behind what's called fire taping, is to seal the wall to eliminate air passage, which would feed a fire air.


Roger

(post #102079, reply #13 of 26)

Plus you prevent directly exposing the framing (at joints) to radiant energy from the fire.

There's really no reason to NOT tape a firewall. It's fast (one coat'll do it), cheap, and improves the insulating value of the wall by reducing air infiltration. It doesn't have to be pretty.


If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #102079, reply #14 of 26)

GP and others have dozens of fire wall assemblies in CAD form on the web.

but standard residential is as you have described WITH the joints taped and mudded. The inspector is right. Time top get with it and quit losing ground arguing with him.

The code book won't desctibe every aspect of any assembly. Rather, it describes the desired goal with language such as"...shall be designed to..." and then leaves it to designers to prove they meet that goal. so standaard assemblies get accepted after testing by the larger manufacturers.

 

 


Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #102079, reply #15 of 26)

Baed on LA codes: In Residential construction there are two types of wall to consider and that may be why there is some confusion. One would be the wall between the garage and attached house. That requires only some of the details of a fire resistive wall. I.e. fire caulking penetrations is not required, one layer of 5/8 Type X drywall on both sides, tight fitting solid door with self closing mechanism.

The other wall is that near a property line. It needs to be one hour construction which normally means Stucco outside. This is to prevent fire from next door to spread to this structure. Some codes require drywall behind the stucco, but most do not for this application. Typically windows are not permitted in this wall.

As far as what detail, our codes have specific language or defer to the Gypsum Handbook of Fire Resistive Assemblies.