How to Plan a Cantilever Rack Layout for Lumber, Pipe, or Sheet Goods

If you're storing lumber, pipe, tubing, sheet goods, or other long material, you've probably already figured out that standard pallet rack wasn't designed for your product. Getting the storage right matters — not just for space efficiency, but for safety, workflow, and the ability to actually find and pull what you need without a forklift hunt.

Cantilever rack is the right tool for the job. But like any rack system, the difference between a layout that works and one that frustrates you for years comes down to the planning. This guide walks through what you need to think about before you buy a single upright.

Know Your Product Before You Design Anything

Everything in a cantilever rack layout starts with the product. Not the building, not the budget - the product. Here is what you need to nail down:

• Maximum product length - this determines arm spacing and bay configuration
• Product weight per unit or bundle - this drives your arm and column load ratings
• Product width and height - affects how many tiers you can stack and arm length needed
• How product is loaded and unloaded - forklift, crane, manually? This changes your aisle requirements
• How often product turns - fast-moving SKUs need better accessibility than slow-moving stock

Measure Your Space - All of It

Before you sketch a single rack run, you need accurate facility measurements. Don't rely on a building spec sheet from 1987. Walk the floor with a tape measure or laser and document:

• Clear height - the usable height from floor to the lowest obstruction (beams, sprinklers, HVAC, lighting)
• Column locations - building columns are immovable and they will affect your layout
• Floor condition - cantilever rack puts significant point loads on the floor; know your slab capacity
• Dock door and aisle entry points - your layout needs to work with how product moves in and out
• Any fixed equipment - electrical panels, floor drains, fire suppression drops

Clear height is especially important with cantilever rack because the arms extend outward and require clearance for both the product and the loading equipment. A building that looks tall enough often isn't once you account for the column base plates, the top arm tier, and the product sitting on it.

Decide Between Single-Sided and Double-Sided

This is one of the most fundamental decisions in a cantilever layout, and it has a big impact on your floor space efficiency.

Single-Sided Cantilever Rack
Arms extend from only one side of the column. These are typically used against a wall or in situations where you only need access from one direction. They're also common when product is loaded from overhead (crane or gantry) rather than from the side.

Double-Sided Cantilever Rack
Arms extend from both sides of the column, giving you storage on two faces from a single aisle or from two aisles. Double-sided configurations are generally more space-efficient per square foot of floor space, but they require aisle access on at least one side - and ideally both.

Determine Arm Length and Spacing

Arm length and arm spacing are where a lot of DIY cantilever layouts go wrong. Here's how to think about each.

Arm Length
Arm length should be long enough to support your product without overhang creating a tip hazard, but not so long that you're paying for capacity you'll never use. A general guideline: the arm should support at least 2/3 of the product length when loaded on multiple arms. For most lumber and pipe applications, 36" to 48" arms cover the majority of scenarios.

Arm Spacing (Vertical)
Vertical arm spacing determines how many tiers you can fit within your clear height and how much product fits on each tier. The spacing needs to account for:

• The height of the product bundle or stack on each arm
• Clearance for the loading equipment (forklift forks, crane hook)
• A safety buffer - at least 6" of clearance above your tallest load is a reasonable minimum

In practice, arm spacing of 18" to 24" works for most flat or bundled material. Taller or irregularly shaped product may require 30"+ between tiers.

Column Spacing (Bay Width)
Column spacing - the distance between uprights - is largely driven by your product length. The general rule is to use at least 3 support points for any product: two columns and an arm. For a 16-foot board, for example, you'd typically want columns spaced no more than 8 feet apart to prevent sag and ensure stable support.

Plan Your Aisles - and Don't Shortchange Them

Aisle width is one of the most underestimated variables in warehouse layouts, and with cantilever rack it matters even more than with pallet rack. Why? Because the arms extend into the aisle space and your product extends beyond the arms. You're not just making room for a forklift - you're making room for a forklift carrying a 20-foot piece of pipe.

Here are typical aisle width guidelines:

• Counterbalance forklift - 12' to 14' minimum working aisle for long material
• Reach truck - not ideal for cantilever applications due to side reach limitations
• Overhead crane or gantry - aisle width is less critical but height clearance becomes the constraint
• Manual or hand truck loading - a 6' to 8' aisle is workable for shorter material

Think Through Your Loading Method

How you load and unload the rack will influence nearly every dimension in your layout. The three most common methods for cantilever rack are:

Forklift Loading (Side)
Most common for lumber yards and industrial pipe and tube storage. Forks slide under the bundle and load from the side. Requires clear aisles and arms that allow clean fork entry without catching. A slight upward arm incline (3°-5°) is often recommended to prevent material from sliding off under load.

Crane or Overhead Loading
Common in steel service centers and fabrication shops. Product drops in from above, so top clearance is critical. Single-sided rack against a wall is often used in these configurations. You can generally run tighter aisles because you're not maneuvering a loaded forklift.

Manual Loading
For lighter, shorter material like molding, dowels, or small-diameter pipe. Lower arm heights (under 60") and shorter arms make sense here. Safety bars or end stops are especially valuable to prevent material from being pulled off the wrong end of the arm.

Don't Forget the Accessories That Make It Work

A cantilever rack system is more than columns and arms. These accessories are worth building into your plan from the start - not adding as an afterthought:

• Arm stops / end lips - prevent product from sliding or rolling off the end of the arm
• Divider pins - help separate different SKUs or bundle sizes on the same arm tier
• Column base protectors / guards - protect columns from forklift strikes at the base
• Safety signage and load rating placards - required by ANSI/RMI standards and critical for safe operation
• Lighting - long rack runs in industrial settings are often poorly lit; build in lighting from the start

A Few Quick Rules of Thumb

• Product length drives column spacing - never go less than 3 support points per piece
• Always design for your heaviest load, not your average load
• Clear height minus top arm tier plus product height plus forklift clearance = your usable vertical range
• Double-sided rack is almost always more space-efficient unless you're working against a wall
• Add more aisle than you think you need - you'll use it

When to Bring in an Expert

For straightforward applications - a single run of rack in a small shop, for example - the steps above give you what you need to put together a solid layout. But for larger installations, multi-product environments, or facilities with seismic requirements or unusual floor conditions, it pays to have a specialist review the design before you order.

SJF's warehouse design team has planned and installed cantilever rack systems for everything from small lumber dealers to large-scale steel distributors. We offer free layout consultations and can produce engineered drawings for permit-required installations. If you're not sure where to start, reach out - the design conversation is free and usually takes about 30 minutes.