Zipper Door Count Calculator

Where Zipper Doors Are Used

Zipper doors are commonly installed in temporary poly walls to control dust and maintain separation between occupied spaces and active work. They support staging corridors, negative-air setups, and controlled worker movement in renovations, fitouts, and restoration scopes.

Key Drivers of Door Quantity

Door count is primarily driven by the number of isolated zones and the number of distinct access needs. Separate personnel and material routes reduce congestion and keep clean/dirty paths organized. Transition doors are added where airlocks or anterooms create sequential barriers.

Recommended Allowances for Spares

Spares protect schedule continuity when a zipper tears, adhesive fails, or a door must be relocated. A practical approach is to add a small fixed spare quantity for immediate replacement and then apply a percentage allowance (often 10–20%) for ongoing changes across longer projects.

Procurement and Packaging Strategy

Contingency accounts for re-sequencing, added rooms, and access plan revisions. If doors are purchased in bundles, rounding to a pack size prevents shortfalls while simplifying ordering. Documenting the calculation supports field requests, change management, and consistent restocking.

Worked Example Using Project Inputs

Example data: zones 6; personnel per zone 1; material shared total 1; egress per zone 1; transitions 2; fixed spares 2; spare percentage 15%; contingency 10%; pack size 1.

Base = (6×1) + 1 + (6×1) + 2 = 15. After fixed spares = 17. After spare % = ceil(17×1.15) = 20. Before pack rounding = ceil(20×1.10) = 22. Final recommendation = 22 door kits.

1) What does “Work zones” represent?

Work zones are separate contained areas needing controlled entry, such as rooms, wings, or tenant spaces. More zones typically increase doors because each area needs at least one access point.

2) When should I use “Shared site total”?

Use shared totals when one common entrance serves multiple zones, such as a single corridor staging point. It prevents overcounting doors that are not duplicated per room.

3) Why include emergency egress doors?

If the safety plan requires dedicated exit paths, egress doors ensure routes remain available without compromising containment. This input adds doors either per zone or as a shared total.

4) What are transition doors?

Transition doors cover airlocks, anterooms, or sequential barriers where workers pass through multiple layers of containment. Add one for each additional controlled transition in the route.

5) How do fixed spares and spare percentage differ?

Fixed spares add immediate replacements for damage or urgent changes. Spare percentage scales the allowance based on project size, covering ongoing adjustments over time.

6) What does contingency percentage cover?

Contingency accounts for scope growth, rework, access plan changes, and sequencing shifts. It is applied after spares to reduce the risk of running short during active construction.

7) Why use pack size rounding?

If door kits are purchased in bundles, rounding up to the nearest pack aligns the result with procurement. It simplifies ordering and avoids partial-pack shortages in the field.