Shaftwall Construction

[TCGConstruction]

I have an upcoming project that the architect wants a CH shaftwall system built against an existing fire wall.

Deck is 19-20' high.

My question:

Can I stack two 10' sections of the CH studs, supporting the joint off of the existing wall or do I need to special order 20' CH studs to span the entire distance?

My supplier thought it was odd when I asked if I could get 20' long CH studs and suggested I just stack two 10' tall sections. USG website says not to stack the shaftwalls, though.

Again, this is not being used to line and actual shaft opening. Architect wants the extra protection between commercial units, the room is being use to store O2 tanks.


Thanks!!!

 

[classicT]

Need to visit with the architect and see if he is doing this to meet a required fire rating, and if so, how his/her design is done. Supporting via an existing rated wall assembly can be an issue if the fire ratings are independent of one another and exposure is from both sides. Basically, if one wall supports the other, you can't add the fire ratings together. The "combined rating" would only work in a single direction of exposure. (Side note - the scenario I am proposing is an over-simplification of design principles).

File a request for an ASI (Architect's Supplemental Instruction) and have the AoR perform the design as it is their responsibility anyways.

 

[TCGConstruction]

OK, I will be seeing the GC in the morning and I can call the Architect in the afternoon.

The drawings are only calling for a 1hr rating on the shaftwall, and the existing wall is already a 1hr firewall between two units.


A side question....does anyone know if CH studs come in 20 foot lengths?

 

[JPohling]

some notes from Clark Dietrich:

 

[Tim Mailloux]

OK, I will be seeing the GC in the morning and I can call the Architect in the afternoon.

The drawings are only calling for a 1hr rating on the shaftwall, and the existing wall is already a 1hr firewall between two units.


A side question....does anyone know if CH studs come in 20 foot lengths?

Are you sure its a FIRE WALL and not a FIRE BARRIER or FIRE PARTITION? The minimum FIREWALL rating in the code is 2 hour.

 

[classicT]

Are you sure its a FIRE WALL and not a FIRE BARRIER or FIRE PARTITION? The minimum FIREWALL rating in the code is 2 hour.

Given the OP is on the contracting side, I am quite sure he simply meant a fire 'rated' wall. As for the type of the fire resistance rated assembly, it is likely a fire barrier given that it is a 2-hr rated assembly and is between commercial tenant spaces.

Architect wants the extra protection between commercial units

 

[Sleepy]

Given the OP is on the contracting side, I am quite sure he simply meant a fire 'rated' wall. As for the type of the fire resistance rated assembly, it is likely a fire barrier given that it is a 2-hr rated assembly and is between commercial tenant spaces.

I've never liked the "fire wall" terminology. The old UBC used the term "area separation wall" or something like that and changing to "fire wall" introduced all sorts of confusion.

 

[classicT]

I've never liked the "fire wall" terminology. The old UBC used the term "area separation wall" or something like that and changing to "fire wall" introduced all sorts of confusion.

I agree. UBC I think just had fire separation walls, no differentiation between fire walls/barriers/partitions.

It would be better understood if it were something like fire separation, fire barrier, fire partition. I'm not sure that separation is the right word, but I took it from the floor system equivalent (horizontal separation) of a fire wall for simplicity. Makes more sense to me. Gives a sense of cascading performance and significance.

 

[Jay Smith]

This table shows the C-H stud limit at 21’-8” for 5 PSF and L/120, so one would think Clark-Dietrich can supply the studs to build it.

https://www.itools.clarkdietrich.com/submittalpro/dyn_pdf/%7B%22pdf_type%22%3A%22individual_product%22%2C%22project_product_code%22%3A%22product%7Cct_shaftwall%7Eproduct_code%7C400CT-21%22%7D/CD_400CT-21.pdf