The pipe route is simple until it reaches the wood. This is the moment to change the drawing, not quietly change the joist.
Identify what is actually there
First identify the member. Solid lumber, I-joists, and engineered beams have different limitations. Record product markings where visible, the support locations, existing holes, and proposed pipe route for the designer or product technical team. Include an overall photo as well as the cut. For an I-joist, the narrow top and bottom edges are its flanges; permission for a hole through the middle web does not mean those edges can be cut.
Weyerhaeuser's TJI hole guidance is specific to those joists. Do not apply its web-hole rules to flanges, other engineered products, or ordinary lumber. The permitted detail depends on the actual member and conditions.
Give the pipe another option
A lower ceiling zone, a shifted fixture, or a different routing may be preferable to a structural alteration. Have the plumber and designer compare those options before the room layout becomes fixed.
If a cut has already happened
- Stop further cutting in the affected area.
- Photograph the damage and product markings without disturbing supports.
- Ask the responsible designer or manufacturer for a project-specific assessment.
- Keep the area accessible until any required repair and review are complete.
Weyerhaeuser's field-issue notes describe why casual notches and substitutions can create avoidable repairs. A generic sistered board is not automatically the answer to an engineered-member problem.
The useful compromise is often a slightly different pipe route. Spend the design effort while changing the route is still cheaper than repairing the structure around it.