Hourly ratings and listed designs: trace the fireproofing thickness
A structural change adds a beam to a distribution warehouse. Its mark appears on the revised steel drawing but not the fireproofing thickness schedule. The applicator suggests using the thickness on the beam beside it so the spray crew can continue.
Use the current project schedule and the applicable listed design together to establish the specified thickness. Member configuration and design restrictions matter; copying an adjacent beam is not a substitute. Where the schedule omits a member or conflicts with the design, obtain a written resolution before treating the proposed thickness as approved.
Build the reference chain for the member
- Identify the exact changed member. Record its mark, level, grids and current structural drawing revision. Obtain the member information through the project documents rather than estimating its size from the floor. Include the change reference so the consultant can distinguish the new beam from the original scope.
- Find the governing project entry. Look for the required rating, fireproofing product and design number in the approved schedule or submittal. Record the source of each item. If the member is missing, mark that gap directly instead of creating a new schedule entry from a similar-looking location.
- Open the complete design information. Match the stated construction and member configuration, then check its notes and referenced general guidance. For Canadian work, confirm the applicable Canadian certification information and its restrictions. A page that identifies a US design alone does not settle the project's Canadian requirements.
- Check the restraint assumption. Record any restrained or unrestrained designation used by the project. Restraint determination belongs with the responsible design professional; visible connections alone do not establish it. If the project entry is unclear, include that question in the same request instead of choosing the most convenient table.
- Send a focused technical query. Attach the changed drawing, missing schedule entry and relevant design reference. Ask for the applicable protection arrangement and required thickness, including any limits or exceptional details. Separate this design question from the later price or time discussion so nobody mistakes commercial agreement for technical acceptance.
- Issue the resolved instruction. Update the controlled schedule through the project's document process and identify superseded copies. Brief the applicator and testing agency on the actual member reference. Keep the decision linked to its location so inspection and closeout can follow the same chain rather than relying on someone's memory.
Common mistakes
- Keeping only a cropped thickness table without its notes.
- Assuming a larger-looking beam makes the neighbour's thickness acceptable.
- Leaving the testing agency with the schedule issued before the change.
Action list
Keep a traceable thickness entry
- Member mark and changed drawing.
- Required rating and product.
- Complete design and guidance reference.
- Restraint designation or open query.
- Written resolution and controlled schedule.
Check your understanding
The added beam looks heavier than its neighbour. Is matching the neighbour's thickness enough?
Show the answer
Appearance does not establish all the design conditions or the permitted protection. Send the actual member information and governing references for a decision, then use the resolved schedule.
