Sleeves and annular space: the gap the system was tested for
The pipe fits easily through the residence’s oversized sleeve. The firestop foreman now finds that the submitted condition does not describe the actual gap. The next floor’s sleeves are about to be placed, so both the existing mismatch and the future opening coordination need an answer.
Annular space is the gap around the penetrant at the opening, not simply the difference between two nominal sizes. Identify the sleeve and the actual outside surface being protected, then measure the relevant gap around it. Compare the complete proposed system’s limits and conditions. A sleeve that makes service installation convenient may still create an unmatched firestop condition.
Make the opening geometry visible
- Identify both boundaries. Record the assembly opening and the sleeve’s actual material, dimensions and projection where present. Identify the penetrant’s outside surface, including covering when applicable. Confirm which boundary the proposed system uses for its gap; do not alternate between bare pipe and insulation dimensions in the same comparison.
- Measure the actual position. Record the closest and widest relevant gaps with a located sketch or permitted photograph. A centered circular pipe has a different geometry from one pushed against a sleeve edge. State an irregular opening or inaccessible segment rather than averaging it into an apparently acceptable number.
- Read limits and associated conditions together. RectorSeal’s public C-AJ-1403 example distinguishes permitted contact from conditions associated with its water rating, and uses a table tied to penetrant and fill choices. It demonstrates that a gap permission can be conditional. Do not borrow the largest gap from one row for another configuration.
- Coordinate planned openings early. Give the responsible trades the reviewed service, covering, sleeve and assembly assumptions before sleeves or openings are finalized. Obtain the necessary technical and structural review of any proposed change. Do not instruct the crew to reduce every sleeve by one trade size as a generic solution.
- Resolve existing differences explicitly. Keep the opening pending with its measurements and a technical review owner. Compare a complete alternative or obtain the required qualified direction. Record the resulting arrangement and verification; adding more material does not by itself bring an oversized gap within a different listed limit.
Common mistakes
- Subtracting diameters and calling that the one-sided gap.
- Ignoring the wide side of an eccentric service.
- Taking a permitted gap from an unrelated system row.
Checklist
Check the sleeve-and-gap record
- Actual sleeve and penetrant surfaces identified.
- Assembly and opening reference linked.
- Relevant closest and widest gaps measured.
- Complete applicable limits compared.
- Existing mismatch and future coordination owned.
Check your understanding
The diameter calculation gives 15 mm, but the pipe is off-centre. Is 15 mm enough to describe the opening?
