Construction Products, Windows, Doors & Fenestration worked example

Fenestration Warranty Reserve at 72% share of units included in this reserve: a worked example

This worked example runs the fenestration warranty reserve numbers for a tougher week than the baseline: 72% share of units included in this reserve instead of the typical 100%. Estimate warranty reserve for windows, doors, and glazing products from shipped units, reserve rate, scope, and fixed campaign costs.

The inputs for this scenario

  • Shipped fenestration units under warranty reserve: 4,200 units (held at the documented default)
  • Warranty reserve accrual per unit: 18 $ / unit (held at the documented default)
  • Share of units included in this reserve: 72 % (the input this scenario stresses; the baseline uses 100)
  • Fixed service campaign and claims administration cost: 15,000 $ (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Variable warranty reserve = shipped fenestration units under reserve × warranty reserve dollars per unit × warranty reserve scope included.
  • total fenestration warranty reserve works out to 69,432 $ at these inputs, and this is the headline figure for the scenario.
  • warranty reserve per unit works out to 16.53 $ / piece at these inputs.
  • variable warranty reserve works out to 54,432 $ at these inputs.
  • fixed service campaign and claims admin cost works out to 15,000 $ at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where share of units included in this reserve sits at 100% and the headline result is 90,600 $, this scenario comes in 23.36% below the baseline at 69,432 $.
  • Use it at period close, when setting next year's accrual rate, or when a known defect triggers a service campaign you must reserve for. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • total fenestration warranty reserve: 69,432 $ (headline result)
  • warranty reserve per unit: 16.53 $ / piece
  • variable warranty reserve: 54,432 $
  • fixed service campaign and claims admin cost: 15,000 $

Run it with your numbers

  • To rerun this with your own numbers, open the live Fenestration Warranty Reserve calculator, set share of units included in this reserve to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.