How Do You Check a Warehouse’s Sprinklers for a New Tenant?

A warehouse sprinkler system is checked for a new tenant by comparing what the system was designed to protect, as recorded on the hydraulic design information sign and in the hydraulic calculations, with what the new tenant plans to store, classified under National Fire Protection Association (NFPA) 13. The comparison covers the commodity class, the storage height and arrangement, the sprinkler type and design density or pressure, the water supply, and the physical condition of the system on the floor. The result is a sealed evaluation letter or gap report that says the system is adequate as is, adequate within stated operating limits, or in need of modification before move-in.

The evaluation is an owner’s duty, not an option. NFPA 25 (2023), the inspection, testing and maintenance standard adopted in every state DGA works in, makes the property owner responsible for having the system evaluated before the occupancy, use, process or materials change, and promptly when such a change is found (Sections 4.1.6 and 4.1.7), and the fire codes require updated construction documents and permits when high-piled storage changes. This article sets out the 8 steps, the documents, the timeline, the findings that most often stop a move-in, and what each jurisdiction expects to be filed.

The 8 Steps of a Tenant Sprinkler Evaluation

The sequence runs from the existing records to the filings, and it applies whether the system is a control mode density area (CMDA) design, a control mode specific application (CMSA) design, or an early suppression fast response (ESFR) design.

1. Gather the existing records. The landlord provides a photo of the hydraulic design information sign at each riser, the sprinkler as-built drawings, the hydraulic calculations, the last hydrant flow test, the most recent NFPA 25 inspection and test reports, and the prior tenant’s high-piled storage plan or permit. NFPA 13 (2022) requires the sign to state the design area location and size, the discharge density, the required flow and pressure at the base of the riser, the occupancy or commodity class with the maximum storage height and configuration, the hose stream allowance and the installing contractor’s name (Section 29.4; Section 28.5 in the 2019 edition adopted in Pennsylvania and Maryland). NFPA 25 (2023) Chapter 4 requires the owner to keep the as-builts, acceptance tests and calculations for the life of the system.
2. Define the new tenant’s storage. The tenant supplies the product list, the packaging (cartoned, exposed, encapsulated, on wood or plastic pallets), the storage method, the maximum storage height, rack depth, flue spaces, aisle widths and the floor area each product will occupy. The worst case the tenant may reach is what gets evaluated, not the opening-day layout.
3. Classify the commodity under NFPA 13 Chapter 20. The FPE assigns each storage area a class: Class I to IV, cartoned or exposed Group A plastics, expanded or unexpanded, or a high-hazard commodity that falls outside Chapters 20 to 25. The classification method and the plastic content thresholds are set out in NFPA 13 (2022) Chapter 20 (Class IV in Section 20.4.4, Group A plastics in Section 20.4.5), and DGA’s article on commodity classification under NFPA 13 explains how the call is made when the plastic share is close to a threshold.
4. Compare the placard design basis with the new hazard. The FPE lays the new class, height and arrangement against the design the placard records: density and area for a CMDA system, minimum pressure and sprinkler count for CMSA and ESFR, sprinkler K-factor and temperature rating, whether in-rack sprinklers are required at the new height, and the clearance from the top of storage to the deflector. The design criteria come from NFPA 13 (2022) Chapters 20 to 25, and the article on how high storage can go under ceiling-only sprinklers gives the height limits by sprinkler type.
5. Verify the water supply and re-run the calculation. A hydrant flow test run to NFPA 291 and not more than 12 months old (the limit NFPA 13 (2022) Section 4.5.1.1 sets for working plan submittals unless the AHJ approves otherwise) is plotted against the new demand plus the hose stream allowance. Where the existing calculation cannot be found, the system is re-calculated from the as-builts. A supply that falls short at the new demand raises the fire pump question, covered in DGA’s article on how engineers decide whether a fire pump is needed.
6. Walk the floor. The FPE or the inspecting engineer checks the field against the drawings: obstructions under ESFR sprinklers from new ducts, lights or conveyors; solid shelving in racks; open-top containers; missing, painted or loaded sprinklers; corrosion and microbiologically influenced corrosion on exposed pipe; and the condition of the control valves and the fire department connection. DGA’s article on why open-top bins defeat rack sprinklers covers the finding that most often surprises tenants.
7. Write the gap report. The report states one of three outcomes for each storage area: compliant as is; compliant with operating limits (a maximum height, a commodity ceiling, an aisle width or an arrangement the tenant must hold); or needs modification, with the scope of the sprinkler work. The report is sealed by a licensed Professional Engineer (PE) and names the code editions it was evaluated against.
8. File what the change triggers, before move-in. Where modification is needed, the sprinkler contractor files a permit with sealed shop drawings and calculations under NFPA 13 (2022) Chapter 30, existing system modifications (Chapter 29 in the 2019 edition). Where the storage changes, the FPE files an updated high-piled storage plan under 2021 International Fire Code (IFC) Section 3201.3 and the operational permit under Section 3201.2 where the jurisdiction issues one. In New York City the tenant applies for the FDNY high-piled storage permit in its own name.

Figure 1: From Records to Filing in 8 Steps

1Gather the placard photo, as-builts, calcs, flow test, NFPA 25 reports and prior storage plan

2Define the tenant’s commodity, packaging, height, arrangement and areas (worst case)

3Classify each area under NFPA 13 (2022) Chapter 20

4Compare the placard basis with the new hazard: density or pressure, K-factor, in-rack need, clearance

5Flow test under 12 months old (NFPA 291); re-run the hydraulic calc against the new demand

6Walk the floor: obstructions, solid shelves, open-top containers, missing heads, corrosion

7Sealed gap report: compliant as is, compliant with limits, or needs modification

8File the modification permit, updated storage plan and FDNY permit (NYC) before move-in

Which Documents the Evaluation Needs, and Who Prepares Each

Six parties hold the records a sprinkler evaluation depends on, and the evaluation stalls when any one of them is assumed to be someone else’s job. The table lists each document, the code basis and the party that normally prepares it.

Figure 2: Records to Gather Before the Evaluation Starts

Placard photo at every riserDesign area, density or pressure, commodity, height, hose allowance, installing contractor (NFPA 13 (2022) 29.4)

Sprinkler as-builtsSprinkler type, K-factor, temperature rating, spacing, pipe schedule

Hydraulic calculationsDesign area, demand at the base of riser, supply curve used at acceptance

Hydrant flow testUnder 12 months old, run to NFPA 291, same main that feeds the riser

NFPA 25 reportsLast annual, 5-year internal inspection, open deficiencies (NFPA 25 (2023) Chapter 4)

Prior high-piled storage plan or permitWhat the fire code official last approved for the space (2021 IFC 3201.3)

Tenant’s storage exhibitProducts, packaging, pallets, height, racks, aisles, areas, worst case

Missing any one of these adds 1 to 4 weeks to the evaluation

DGA evaluates existing warehouse sprinkler systems against new tenants’ storage, classifies commodities and files the resulting plans and permits across New York, New Jersey, Pennsylvania, Maryland and Delaware. Project briefs get confirmation and preliminary code feedback within one business day. See where DGA works →

How Long the Evaluation Takes and What Drives Delays

As of October 2026, a sprinkler evaluation for a new warehouse tenant takes 2 to 6 weeks when the placard, the as-builts, the calculations and a current flow test all exist. The classification and comparison take 1 to 2 weeks once the tenant’s product data arrives; the site walk takes a day; the report takes about a week. Review time for any filing runs on top of that on the jurisdiction’s clock.

Three things push the work past 6 weeks. A flow test older than 12 months has to be rerun, and water purveyors in the region schedule tests 1 to 4 weeks out, longer in winter when some utilities suspend testing. A missing hydraulic calculation adds 1 to 3 weeks of field measurement and re-calculation, and a tenant who cannot yet state the product mix or the final rack height delays the classification and everything after it.

Where the outcome is “needs modification”, the schedule becomes a sprinkler permit schedule. In-rack sprinklers, a density upgrade or a fire pump add months, not weeks, and the move-in date usually moves with them. The industrial and high-hazard sector page describes how DGA sequences that work for warehouse and distribution operators.

What Filing a Tenant Change Triggers in Each State

The evaluation report is the same in every state. What it triggers differs, because the sprinkler permit sits with the building department, the storage plan and operational permit sit with the fire code official, and New York City adds a separate FDNY permit. The table lists the filings a tenant change normally triggers and the AHJ for each; local amendments and the exact permit names should be confirmed before filing.

Editions as listed in DGA’s Fire Code Cheat Sheet for NY, NJ, PA, MD and DE. Local amendments are not shown.

Why Tenant Sprinkler Evaluations Fail, and the Fix for Each

Most findings are not design errors in the original system. The system was built for a tenant who has since left, and the building is being asked to protect something it was never designed for. The pairs below are the findings DGA sees most often on warehouse tenant evaluations, each with the fix.

No placard, so the design basis is unknown. The sign is missing, painted over or illegible. Fix: locate the calculations or the acceptance documents; failing that, measure the system in the field, re-calculate it, and install a new sign that meets NFPA 13 (2022) Section 29.4.

The hydraulic calculation cannot be found. The installing contractor is gone and the landlord’s file holds only the drawings. Fix: re-calculate from the as-builts and a current flow test, and keep the result with the NFPA 25 records as the new design basis.

Plastics creep. The placard says Class III or IV and the tenant’s product is cartoned Group A plastics, or the pallets are plastic, or the loads are stretch-wrapped over the top. Fix: classify under NFPA 13 (2022) Chapter 20 using the actual plastic share, then limit the plastics to areas the design covers or upgrade the protection.

Racks taller than the design. The placard states 20 ft and the racks are 28 ft. Fix: hold storage at the placard height with the top beam level left empty and written into the lease, or add in-rack sprinklers or an ESFR design rated for the new height.

Solid shelving. Plywood or sheet steel decking blocks water from reaching the lower tiers. Fix: swap to decking that is more than 50 percent open with flues maintained (NFPA 13 (2022) Section 20.5.3.1.1), or add in-rack sprinklers below the solid shelves (Section 20.19.3, with the in-rack design in Chapter 25).

ESFR obstructed by new work. Ducts, high-bay lights, conveyors or a mezzanine sit inside the obstruction zones ESFR sprinklers need. Fix: relocate the obstruction or add sprinklers below it under the NFPA 13 (2022) Chapter 14 obstruction rules.

Old flow test. The supply curve on the calculation dates from the original construction. Fix: run a new test to NFPA 291 and re-plot; supplies in older industrial areas often drop 10 to 20 psi over a decade.

Dry system with no accelerator. A dry pipe system over an unheated dock or freezer delivers water late, and storage designs assume wet-pipe delivery unless the design accounts for the delay. Fix: check the water delivery time against the limit NFPA 13 sets for dry systems protecting storage, add a quick-opening device, or convert the area to a wet or preaction system.

Figure 3: Three Outcomes of the Evaluation

What Happens After the Evaluation Is Approved

An evaluation that ends in outcome A or B is only as good as the limits the tenant keeps. The operating limits, such as a maximum storage height, a ban on exposed plastics or a minimum aisle width, are written into the lease as a storage exhibit and into the high-piled storage plan on file with the fire code official. Fire inspectors measure against the plan on file, and a tenant who stacks one beam level higher than the plan has created a violation even when the racks were never touched.

The evaluation is re-checked whenever the tenant’s product mix changes, since NFPA 25 (2023) Chapter 4 requires the owner to evaluate the system before such a change. NFPA 25 sets no annual building review, but many owners re-check once a year. In New York City the FDNY high-piled storage permit renews each year after inspection, which makes that a natural date. Where DGA provides the annual look, it runs as a PE site inspection under the firm’s fire protection inspection service, separate from the contractor’s NFPA 25 testing.

The sealed evaluation, the classification letter, the flow test and any re-calculated hydraulics stay with the sprinkler records for the life of the system. The next tenant’s evaluation then starts from a known design basis, which is the difference between a 2 week evaluation and a 6 week one.

Frequently Asked Questions

This article is general information, not a code determination for any project. Code editions, local amendments and reviewer practice change; confirm the adopted code and the authority having jurisdiction for the building before relying on an existing sprinkler system for a new use.