Design Fire Barrier

A rated wall is not a wall type. It is a continuous surface that has to hold a rating from the floor it sits on to the deck above, along its whole length, past every duct, pipe, conduit, joint and door in it. It is drawn as a hatch on a plan and it fails at the places the plan does not show.

Workflow

Step 1. Establish what kind of separation it is

Ask, in one message:

1. What kind of separation is this, and what code section requires it? Quote the section.
2. What is the required rating, and where did the figure come from?
3. What tested assembly are you using, and do you have the listing?
4. What is above: a deck, a rated floor assembly, a rated ceiling membrane, a plenum?
5. What is below: a slab, a rated floor, a raised floor, a void?
6. Is the building sprinklered, and does that change what your quoted section permits?
7. What passes through it, and is there an MEP set?

The kind of separation decides everything. Two assemblies with the same hourly number can have entirely different continuity requirements, and a wall drawn to the ceiling because "it is only a one-hour" is the most common version of this mistake.

Step 2. Trace the surface, top and bottom first

Report the assembly as a continuous surface:

• Top. Where does it terminate, and does the quoted section allow that termination? Deck, rated ceiling, or a rated floor above. If it stops at a suspended ceiling, name what makes the ceiling part of the rated assembly, or say that nothing does.
• Head of wall joint. The gap between the top of the wall and the structure, and the listed joint system that closes it. This joint has to accommodate movement and hold a rating at the same time, and that is a listed system, not a detail to be invented.
• Bottom. What it sits on, and whether the floor construction is continuous beneath it.
• Ends. Where it terminates horizontally: at another rated assembly, at an exterior wall, at a corner. Say what makes the junction continuous.
• Length. Any change in construction along its run, any offset, any place it steps around structure.

Step 3. Work every interruption

For each, name what closes it and what listing that closure comes from. Leave every number as a question.

Interruption	Type	What closes it	Listing needed from you	Movement?

Work through:

• Penetrations. Every pipe, conduit, cable tray, sleeve. Combustible and non-combustible penetrants are different listings.
• Ducts. Whether a damper is required, what kind, and how it is accessed. Access is a design decision and it usually appears late and badly.
• Doors. Rating, hardware, closer, and whether the opening is permitted at all in this kind of separation.
• Glazed openings. Whether permitted, what kind of glazing, and whether it is rated for temperature rise as well as flame.
• Joints. Head of wall, wall to wall, expansion joints crossing the barrier.
• Structure passing through. A beam or a column crossing the plane, and whether it is separately rated.
• Recessed items. Boxes, panels, cabinets, and whether the assembly's rating survives a recess in it.

Step 4. Check the interruptions against the whole

Two questions that only make sense over the whole assembly:

• Aggregate limits. Does your quoted section limit the total area or number of openings in this kind of separation? If so, the individual openings have to be added up, and that total is a number you supply and check.
• Opposite sides. Are penetrations or recesses on opposite faces offset as the tested assembly requires?

Step 5. Report

• The surface trace, top to bottom, with any termination that the quoted section does not appear to allow flagged.
• The interruption table, with every missing listing counted.
• Interruptions with no closure identified, listed first.
• What is on the MEP set that this assembly does not yet account for, or the statement that no MEP set was supplied.
• Every number still open.

Close with the standing limits: no rating was recalled, no listing was verified, and structural and movement questions at the head of wall are open.

Step 6. Save, if asked

Ask whether to write the trace to a file and where.

Rules

• Never supply a rating, an opening limit, or a listing number.
• Never assume the separation type. Ask, and quote what requires it.
• Trace top and bottom before anything else. Termination is where rated walls most often fail.
• Every interruption names a closure and a listing, or is flagged as having none.
• Head of wall is a listed system, never a drawn detail.
• Say on every run that no listing was verified.
• Quoting a code clause found by web search is not quoting the code.

Anti-patterns

• Treating the hourly number as the whole requirement and ignoring what kind of separation it is.
• Stopping a rated wall at a suspended ceiling with nothing making the ceiling part of the assembly.
• Drawing the head of wall as a sealant joint.
• Recalling a tested assembly number or a firestop system number.
• Ignoring damper access until the ceiling is drawn.
• Counting openings individually when the section limits the aggregate.
• Assuming a sprinklered building relaxes a requirement without quoting the text that says so.
• Treating a recessed panel as too small to matter.

Resources

None. This skill is one file. Output is written directly at the path you choose.