Are reglets an "opening" in a wall assembly?

[Yikes]

I have a coworker who just completed a plan check, and the plan checker made him add up the SF area of a 1" wide aluminum reglet reveal on the wood-framed exterior plaster wall, and include it in the tally along with doors and windows per Table 705.8. It still added up OK for him, but:

Q1: do you consider reglets to be an interruption of the fire-rated assembly?
Q2: do you consider them to be an "opening" in a wall?

 

[RLGA]

I have some questions of my own:

Q1: Is the exterior wall required to be rated from both sides or just the inside?

• If rating is required from both sides, then it depends on the answer to my next question.
• If rating is from the interior only, then the answer to both of your questions is "no."

Q2: Is the stucco plaster a required component for the rating, or just an approved exterior wall covering?

• If the stucco plaster is only an approved exterior wall covering over a rated assembly, then the answer to both of your questions is "no."
• If the fire rating depends on the stucco plaster, then the answer to your first question is "maybe," and the answer to your second question is "no." The "maybe" response depends on the tested assembly and what was included in the test sample. Sometimes expansion joints, crack control joints, etc. may have been a part of the tested assembly. Decorative aluminum reveals probably may not have been tested, but I wouldn't consider them an opening.

Joints that go through the assembly would be considered openings.

 

[Yikes]

For sake of discussion, let's call it a type V-A building. And let's say it's in a location that limits maximum amount of openings based on fire separation.

 

[RLGA]

For sake of discussion, let's call it a type V-A building. And let's say it's in a location that limits maximum amount of openings based on fire separation.

If the wall is greater than 10 feet from the lot line, then it need only be protected from an interior exposure; thus, the exterior wall covering (i.e., the stucco plaster) does not factor into the fire-resistance rating of the wall. In this case, the reveals are not needed for the fire-resistance rating and are not considered joints, penetrations, or openings.

If the exterior wall is required to be protected from exposure on the outside and the stucco is a required component of the fire-rated wall assembly, then the reveal could be considered an opening.

 

[ADAguy]

I thought that fire ratings were determined by material type (+) thickness of wall, the reglet reduces that thickness where it occurs, no?

 

[RLGA]

I thought that fire ratings were determined by material type (+) thickness of wall, the reglet reduces that thickness where it occurs, no?

Depends. If your base assembly is rated, then you can apply any applicable finishes permitted by the building code.

For example, let's assume you're required to have a 1-hour exterior wall. This may be achieved by using UL assembly U419 constructed of metal studs and 5/8-inch Type X gypsum board (USG SGX) on the inside and Type X exterior gypsum sheathing (USG SHX) on the outside--that is your 1-hour assembly. You can add exterior wall coverings (e.g. metal siding, stucco, etc.) to the exterior gypsum sheathing side without affecting the assembly's rating, provided the cladding complies with the IBC. Thus, adding reveals to the stucco would not alter the fire-resistance rating of the wall.

Some assemblies may have the stucco cladding as a required component of the rated assembly, so adding reveals that disrupts the continuous stucco plane, would be considered an opening. For example, UL assembly V482 allows 3/4-inch stucco as an alternate veneer to the brick veneer shown as part of the assembly. In this case, the stucco is a required component of the assembly, and any reveals would provide a weakness in the stucco surface and the assembly. On the other hand, since stucco is a portland cement product and that it will crack, I assume that standard control joints (not aesthetic reveals) installed at the recommended spacing would be acceptable within the assembly.

 

[ADAguy]

Control joints do differ from reglets in width and depth, reglets often being used for architectural effect.
It is one thing to attach materials over stucco as you indicate but another to reduce the thickness of the rated material. Also, substitution of plastic reglets for metal is a cause for concern.

 

[RLGA]

Control joints do differ from reglets in width and depth, reglets often being used for architectural effect.
It is one thing to attach materials over stucco as you indicate but another to reduce the thickness of the rated material. Also, substitution of plastic reglets for metal is a cause for concern.

Control joints for stucco are for the full depth of the stucco, but they are not as wide as regrets or reveals. And plastic ones do provide less protection than aluminum ones, but not by much.

 

[Yikes]

Some assemblies may have the stucco cladding as a required component of the rated assembly, so adding reveals that disrupts the continuous stucco plane, would be considered an opening.

I just received a plan check comment: "Revise details to maintain the fire rating behind the aluminum reveal". We show a 7/8" Fry Reglet in a one-hour wood-framed fire assembly. The stucco forms part of that assembly. So this plan checker is saying that I've compromised the wall.
Q1. What's difference between a reglet being a code-allowable opening, vs. a non-compliant, compromised wall assembly?
Q2. If I put 2x blocking behind the reglet, does that mitigate the problem altogether?

 

[mark handler]

Are unprotected windows permitted?

715.1 General
Joints installed in or between fire-resistance-rated walls, floor or floor/ceiling assemblies and roofs or roof/ceiling assemblies shall be protected by an approved fire-resistant joint system designed to resist the passage of fire for a time period not less than the required fire-resistance rating of the wall, floor or roof in or between which the system is installed. Fire-resistant joint systems shall be tested in accordance with Section 715.3.
Exception: Fire-resistant joint systems shall not be required for joints in all of the following locations:
7. Walls that are permitted to have unprotected openings.

 

[Yikes]

Yes, unprotected windows are permitted. Thanks for the reference.

 

[ADAguy]

Yes, unprotected windows are permitted. Thanks for the reference.

So, is it assumed that given the size (width and depth) of most riglets that heat transfer through the metal is not enough to ignite wood studs?

 

[RLGA]

So, is it assumed that given the size (width and depth) of most riglets that heat transfer through the metal is not enough to ignite wood studs?

Not any more than an aluminum or steel window installed in a wood-framed opening.