Thread: Truss End Fire Protection

Recently inspected a brick veneer residence where truss ends were deteriorating due to contact with a band of wet 5/8" drywall which had been installed in a horizontal band at the truss end level on each floor in place of wood sheathing as a fire-retardant method.

(The drywall was wet due to water running down the interior of the WRB, but that's a different issue.)

(I get to tear things up at Water Intrusion Inspections... just like Mike Holmes!)

This seems to me to be a poor construction practice: any water penetrating the wall will wet the drywall, which will more readily absorb water than plywood sheathing, and will likely take longer to dry out. Seems to me that something like ToughRock would be a better choice, and something like DensShield better still.

However, the builder says this a common residential construction method to meet code requirements, and accepted construction practice here in Chicago.

I can't seem to GOOGLE up ANYTHING about truss end protection at exterior veneer walls, anyone have any pointers?

BTW, this is an excellent example of why IMO foam installation is a just awful idea at the underside of flat roofs.

I haven't looked at the Chicago codes in a couple of years, but there is no requirement for truss end protection I recall ever having seen.

There are fire rating requirements which would require some options, one frequent option being to install rated gypsum exterior sheathing (Densglass Gold is the frequently installed option).

The requirements for a fire rating from the exterior side would depend on various factors, including, but not limited to: apartment/codo building; townhouses: separation between buildings; etc.

But that fire rating would apply to the entire exterior wall and openings in that wall, not just to truss end fire protection.

I'm using my phone right now so the photo is not as nice, big and as clear as on my computer - I will look at it again later.

Is the OSB wet? (added this with edit: Oh, wait, what looks like OSB is the gypsum board, got it now.)

I am sure that you wrote up the truss plates which is not embedded (much at all) on the two visible trusses ... which is an indication that a good percentage of the other truss plates may be the same way.

Originally Posted by Jerry Peck

I haven't looked at the Chicago codes in a couple of years, but there is no requirement for truss end protection I recall ever having seen.

There are fire rating requirements which would require some options, one frequent option being to install rated gypsum exterior sheathing (Densglass Gold is the frequently installed option).

The requirements for a fire rating from the exterior side would depend on various factors, including, but not limited to: apartment/codo building; townhouses: separation between buildings; etc.

But that fire rating would apply to the entire exterior wall and openings in that wall, not just to truss end fire protection.

I'm using my phone right now so the photo is not as nice, big and as clear as on my computer - I will look at it again later.

Jerry,

No sheathing is visible except for that in the truss cavities I opened, that's the back-side of the WRB you are looking at where the gypsum board has deteriorated and fallen away.

There were pics taken during construction that show the WRB and gypsum board before the brick veneer was installed, I'm trying to get one to post to make things clearer.

Based on my experience w/ Chicago codes, where this type of fire seperation is required, it's required everyhwere (rated windows, etc.), so like you I'm unclear why only the truss ends are "protected".

Might be a question for Markus Keller.

Originally Posted by Jerry Peck

Is the OSB wet? (added this with edit: Oh, wait, what looks like OSB is the gypsum board, got it now.)

I am sure that you wrote up the truss plates which is not embedded (much at all) on the two visible trusses ... which is an indication that a good percentage of the other truss plates may be the same way.

Jerry,

This was a water intrusion, not a home inspection or PCR, so I was only looking at construction details as they directly affected the water intrusion issues - my insurance requires that I restrict the scope of WI inspections or "where would it end"?

Originally Posted by Michael Thomas

Jerry,

This was a water intrusion, not a home inspection or PCR, so I was only looking at construction details as they directly affected the water intrusion issues - my insurance requires that I restrict the scope of WI inspections or "where would it end"?

Micheal,

With the truss plates barely pressed into the wood, the water intrusion wetting and even slightly damaging or softening the wood could cause the limited truss plate penetration to loose their limited grip and fail.

A direct result of water intrusion? The concrete support for the bridge failed because the concrete spalled due to rusting of the steel reinforcement in the concrete support - a direct result of water intrusion? Yes. And if 'yes', then water intrusion could lead to a direct result of the truss plates failing ... aided, of course, by the failure of the truss manufacturer to properly and fully press the truss plates into the wood, but ... but without the water intrusion damaging the wood the trusses may have continued to hold the truss plates for a very long time ...

Depends on how one addresses items like that.

The drunk driver ran into another vehicle, killing the occupants of the other vehicle - the bartender kept serving drinks to the drunk person even though the bartender kept saying 'You are drunk, you shouldn't have any more drinks.', then served the drunk another drink, and another ... is the fault of the accident only that of the drunk driver? Or did the bartender play a part in the accident?

And this, this has happened in Florida: A child finds a handgun which is not locked up and does not have a trigger lock, the child accidentally shoots a playmate, the parent is held responsible because Florida has a law which requires all guns to be kept out of the reach of children and locked up or have a trigger lock ... the child killed was the son of the gun owner - the gun owner suffered twice: first for losing his son, second for being held responsible for the death of his son.

Michael,
Just to be clear, are you saying the band of drywall was only at the ends of the trusses and that the rest of the wall was sheathed with OSB? For multifamily construction there is typically a fire rating requirement within 4 feet horizontally of the part wall. On multi-floor buildings with different units on each floor there could be a requirement like this at each floor level on the exterior walls, but I am not familiar with it. When thinks get wet drywall is not much worse than OSB. The key is don't allow these materials to get wet.

The other material you mentioned would probably perform better when wet, but may not comply with fire-rating requirements.

Originally Posted by Mark Reinmiller

For multifamily construction there is typically a fire rating requirement within 4 feet horizontally of the part wall.

That is when the party wall is separating separate structures (such as townhouses where there are no units above-below another unit).

With apartments, condos, co-ops and the like, the structure is one single structure, then the separation is between units (side-to-side and above-below). Typically, this is done with rated wall assemblies between the units, rated floor-ceiling assemblies between units, and ceiling-roof assemblies between the uppermost units and the roof.

Townhouses are different animals as they are one structure from the ground to the sky above and are separated by rated walls sufficient to allow the "structure" on one side of the rated wall to burn down while the "structure" on the other side of the rated wall remains standing.

Now, given that Chicago is union controlled ... ... I don't know what is required or permitted in those cases in Chicago.

Originally Posted by Jerry Peck

That is when the party wall is separating separate structures (such as townhouses where there are no units above-below another unit).

With apartments, condos, co-ops and the like, the structure is one single structure, then the separation is between units (side-to-side and above-below). Typically, this is done with rated wall assemblies between the units, rated floor-ceiling assemblies between units, and ceiling-roof assemblies between the uppermost units and the roof.

Townhouses are different animals as they are one structure from the ground to the sky above and are separated by rated walls sufficient to allow the "structure" on one side of the rated wall to burn down while the "structure" on the other side of the rated wall remains standing.

Now, given that Chicago is union controlled ... ... I don't know what is required or permitted in those cases in Chicago.

Jerry, I meant to say townhouse instead of multi-family. I am familiar with interior fire-rating requirements for multi-story condos, etc. but I am not familiar with exterior requirements. I have not had much dealings with these pertaining to code compliance.

As you said, things could be much different in Chicago. Regional practices wary widely also.

Originally Posted by Mark Reinmiller

but I am not familiar with exterior requirements. I have not had much dealings with these pertaining to code compliance.

Mark,

The exterior requirements are basically related to three things: a) separate structures (townhouses) or one structure (condos, apartments, etc); b) distance to closest building or property line measured perpendicular to the face of the structure (don't want one structure on fire to cause a nearby structure to catch on fire); c) openings in the wall.

As opening percentage area of the wall increases, the required separation distance between structures increases (it's more complicated than that - to many variables to go over here, but if the structures are 30 feet or greater apart, there is no limit or requirement for the openings in the wall, whether sprinklered, unsprinklered, protected or unprotected - IBC TABLE 705.8).

The drywall is required as fire separation between buildings depending on how close the house is to the property line and adjacent house. Since newer construction in dense neighborhoods tends to have no more than 3' between homes, sometimes less, 5/8" drywall is required.
This is another well intentioned moron idea that works great in books but terrible in the field. If I were in charge, and we know I'm not, I'd get rid of this stupid requirement. At 3' or less of space between the homes the fire is going to jump across if not put out fast enough. From my experience the drywall itself creates more of a problem for the homeowner than it provides as a potential safety improvement. I'd rather see fire rated or coated cdx than drywall.
Our construction around here is so pathetic that problems like this are all too common. Maybe I'm just jaded but I'm thinking more and more Code compliance isn't about safety or minimum standards etc. but more about putting enough requirements in place to keep the idiot contractors from screwing up the house in the first place.

Originally Posted by Markus Keller

The drywall is required as fire separation between buildings depending on how close the house is to the property line and adjacent house. Since newer construction in dense neighborhoods tends to have no more than 3' between homes, sometimes less, 5/8" drywall is required.

Markus,

Required at the truss ends only, or for the entire wall?

Are they permitting drywall or requiring exterior gypsum sheathing?

I've seen exterior gypsum sheathing damaged due to moisture and water leaks as you describe, however, my experience is that OSB deteriorates quicker given the same conditions - and I am referring to the old exterior gypsum sheathing, not the newer products like DensGlass, Dens Shield and the like which are more resistant to that deterioration.

Not required specifically for truss ends but for the wall, can be the entire wall or portions but it depends on proximity, dormers, lot line etc.
Yes Jerry, I was referring to exterior gyp sheathing, black drywall. Problem is it gets damaged or cut poorly a lot and ends up essentially bare drywall exposed to everything.
i'm not a fan of OSB at all. Did have a conversation with the lumber yard rep last month about OSB though. He stated OSB manufacturers are aware of the 'perceived' problems and have been working hard at making all the glues and additives waterproof. Can't say I agree with some of his points though considering what we see in the field.

Originally Posted by Markus Keller

Yes Jerry, I was referring to exterior gyp sheathing, black drywall.

I figured you were referring to exterior gypsum sheathing but wanted to clarify it for all.

Some read "drywall" and think about what is typically referred to "drywall".

Many don't realize there are several different types, which is why I try to avoid using the term "drywall" unless I am referring to the typical and common interior use non rated type.

Many don't know that Type X is not to be installed on a ceiling, that is why Type C is made ... many may not know that Type C exists.

I believe it raises the profressalism bar by using correct terminology and to try to reduce confusion of terms even before that confusion may be present or known to be present.

It is discouraging the number of drywall installers who do not understand that Type C goes on the ceiling (it can go on the wall too, just costs a lot more) and Type X goes on the wall (only), and that Exterior Soffit Board goes on the exterior soffit and ceiling, not Type C ... and on and on ...

I know you and many others know this, but some may not.

Only the truss ends had gypsum boards sheething - that's what's strangest; above and below floor level the sheathing was plywood.

The owner took *lots* of pictures during construction, I'm trying to get one to post to make things clearer.