In-Rack Fire Sprinkler Systems for Warehouses and High-Piled Storage

Warehouses with high-piled or densely packed storage present a particular fire protection challenge. Pallets, cartons and rack structures can obstruct water discharged from ceiling sprinklers, allowing fire to develop between storage levels. An in-rack fire sprinkler system places sprinkler heads and pipework within the racking so water can reach a developing fire closer to its source.

TL;DR

In-rack sprinklers are used where warehouse layout, storage height, commodity type or packaging makes ceiling-only protection insufficient. The correct solution depends on a site-specific fire risk assessment and engineered design. Facilities teams should involve a competent fire protection specialist before installing new racking, changing stored goods or increasing storage height.

What is an in-rack fire sprinkler system?

An in-rack sprinkler system is a network of sprinkler heads and pipework installed at selected levels within pallet or storage racking. The heads respond to heat in their immediate area and discharge water where the fire is developing.

This targeted position is the main difference between in-rack sprinklers and roof-level sprinklers. Ceiling sprinklers protect the building and storage from above. In-rack sprinklers add protection inside the storage array, where solid shelves, tightly packed loads or high rack levels may shield a fire from overhead water.

In-rack protection normally forms part of an integrated commercial fire sprinkler system. It should not be treated as a standard add-on or a substitute for a properly designed roof-level system.

When might a warehouse need in-rack sprinklers?

There is no single storage height or warehouse type that automatically answers this question for every facility. The need and design approach depend on the combined risk presented by the building, rack configuration, commodities, packaging, storage height and available water supply.

High-piled and multi-level storage

As storage height increases, a fire can develop through several rack levels before ceiling sprinklers have a clear path to control it. In-rack sprinklers can shorten the distance between the sprinkler and the fire while addressing areas shielded by goods above.

Obstructed water distribution

Solid shelves, closely packed pallets and certain rack arrangements can create a shadow effect that prevents roof-level discharge from reaching lower levels effectively. Correctly positioned rack sprinklers help deliver water into those protected spaces.

Changing commodities or packaging

A system designed for one storage profile may no longer be suitable after changes to products, packaging, pallet type or stacking arrangement. Plastics, combustible packaging and higher-risk goods may alter the fire load and required protection strategy.

Cold or specialised storage environments

Cold storage, water-sensitive areas and facilities with particular operational hazards may need a different system configuration. Wet pipe, dry pipe or pre-action arrangements may be considered, but the selection must follow the actual temperatures, detection strategy, water-damage exposure and approved design criteria.

How in-rack and ceiling sprinklers work together

A warehouse fire sprinkler strategy is designed as one system. Ceiling and in-rack sprinklers must be coordinated through the same hydraulic design, water-supply assessment and fire protection objectives.

The designer considers how many sprinklers may operate within the required design area, how much water they must discharge and whether pumps, tanks, valves and pipework can support that demand. This is why adding sprinkler heads to existing racking without recalculation can compromise system performance.

For a broader overview of system types and components, see ERF Group’s guide to commercial fire sprinkler systems in South Africa.

Key design factors for warehouse rack protection

Design factor	Why it matters
Commodity and packaging	Different goods and packaging materials present different rates of fire growth and water demand.
Storage height and rack layout	Rack depth, number of rows, shelf type and flue spaces affect sprinkler positioning and water movement.
Ceiling height and overhead protection	The in-rack arrangement must work with the roof-level sprinkler design.
Water supply	Hydraulic calculations determine the required flow, pressure, pumps, tanks and pipe sizes.
Temperature and environment	Freezing conditions, corrosion exposure and water-sensitive operations influence system selection.
Material-handling operations	Forklifts and pallet movement create a risk of impact damage to heads and pipework.
Applicable approval criteria	The design may need to satisfy the authority having jurisdiction, insurer requirements and the applicable standard.

South African compliance and approval considerations

South African warehouse fire protection sits within a wider building and fire-safety framework. SANS 10400-T addresses fire protection under the National Building Regulations, while the detailed sprinkler design must follow the standard and approval basis applicable to the specific project.

The required approach can vary according to the building use, rational fire design, local authority, insurer and system specification. Facilities and procurement teams should therefore avoid assuming that a generic international layout can be copied directly onto a South African site.

The Automatic Sprinkler Inspection Bureau provides useful South African context on sprinkler performance and system design. Project-specific requirements should still be confirmed by the appointed competent professionals and relevant approval authorities.

Installation risks that need practical control

Sprinkler heads installed inside racks are more exposed to forklifts, moving pallets and stock handling than ceiling-mounted heads. Guards, water shields and suitable pipe routing may be necessary where permitted by the approved design.

Required transverse and longitudinal flue spaces must also remain clear. Poor stock placement, altered shelving or unauthorised rack changes can obstruct heat and water movement, undermining the protection the system was designed to provide.

Installation planning should coordinate the sprinkler contractor, racking supplier, warehouse operator and other project professionals. This reduces clashes and helps ensure that pipework does not interfere with loading positions or material-handling routes.

Inspection, testing and maintenance

In-rack sprinkler systems need an inspection and maintenance plan that reflects the approved system and site risk. Routine checks should look for visible impact damage, leaking pipework, obstructed heads, closed or incorrectly positioned valves and changes to rack configuration or stored goods.

Facilities teams should also control changes. Increasing storage height, adding solid shelving or changing the commodity can affect the design basis even if the sprinkler equipment itself has not moved.

Testing and servicing should be completed by appropriately qualified personnel, with records retained for facilities, compliance and risk-management purposes. ERF Group provides fire sprinkler maintenance, overhaul and small works for commercial facilities.

What to prepare before requesting a proposal

A useful project brief helps a fire protection specialist assess the risk and scope the correct solution. Provide current rack drawings, ceiling and storage heights, aisle widths, commodity and packaging details, building plans, existing sprinkler information and available water-supply data where possible.

Also identify planned changes. A proposed expansion, new pallet type, revised product mix or denser storage layout may materially affect the design. Early coordination is usually simpler than altering racks and sprinkler pipework after installation.

Choose a system designed around the actual storage risk

An effective in-rack fire sprinkler system is not selected from a standard product list. It is engineered around the warehouse, the goods being stored, the rack arrangement and the performance required from the complete fire protection system.

ERF Group designs, installs, services and upgrades commercial sprinkler systems, including roof-level and in-rack protection. For an assessment of a new warehouse, storage change or existing rack sprinkler system, Contact us.