Double deep pallet racking is a high-density storage system in which two rows of selective-style pallet racking are placed back-to-back on each side of an aisle, so every bay holds two pallets in depth. Using a reach truck with telescopic (pantograph) forks, it stores 30–40% more pallets than single-deep racking in the same floor area.
This guide explains how a double deep racking system works, its components and typical specifications, the forklifts it needs, when it is the right choice compared with selective, drive-in and push-back racking, and what to check during design, installation and daily operation. It is written for warehouse and factory managers planning or expanding storage in Vietnam.
What is double deep pallet racking?
A standard selective pallet racking system gives direct access to every pallet: one pallet deep, one aisle per row. Double deep racking keeps the same beam-and-upright construction but places a second rack row directly behind the first, connected by row spacers. Each pallet position is therefore two pallets deep, and the aisles that would have served the rear rows disappear.
The result is a semi-selective system. The front pallet of each bay is accessible immediately; the rear pallet can only be reached after the front one is moved. That makes double deep warehouse racking ideal when you hold at least two pallets of the same SKU or batch, which is very common in FMCG, beverage, food ingredients, packaging and component warehouses.
Components and typical specifications
A double deep racking system uses the same core components as selective racking, plus a few parts that make deep storage safe and fast. Exact sizes are always engineered from your pallet, load and building data; the values below are typical ranges for Vietnamese warehouses.
| Component | Function | Typical specification |
|---|---|---|
| Upright frames | Vertical columns with bracing that carry all loads to the floor | Depth 900–1,100 mm; height 6–12 m; column section chosen from load and height |
| Beams | Horizontal load-carrying members, 2 per level | Clear span 2,300–2,700 mm for 2 pallets; 1,000–1,500 kg per pallet |
| Row spacers | Tie the front and rear rows into one double-deep block | Spacer length to create a 100–300 mm flue gap |
| Pallet supports / stoppers | Stop the rear pallet at the correct depth and support pallets crossing the flue | Fitted at every level of the rear row |
| Base plates and anchors | Fix the frames to the slab | 2 anchors per base plate as a minimum, per design |
| Column guards and end barriers | Protect uprights from forklift impact | Fitted at aisle-side uprights and row ends |
| Load signs | Show permitted load per level and per bay | Mandatory at the end of every run |
Height, levels and load per level
Most double deep systems in Vietnam run 4–6 beam levels with a top beam between 6 and 10 m, limited mainly by the reach truck lift height and the building clear height. A typical level carries 2 pallets wide × 2 deep, i.e. four pallets of 1,000–1,500 kg each, so a single level may carry 4–6 tonnes and a full bay 20–30 tonnes. These loads are why slab capacity and anchoring must be checked before installation.
How a double deep racking system works
Double deep racking is operated with a reach truck fitted with double-deep (pantograph) forks, or a dedicated deep-reach truck. The forks extend twice: first to place a pallet in the rear position, then to place the second pallet in front of it. Retrieval is the reverse, so each double-deep lane works on a last-in, first-out (LIFO) basis.
- Putaway: store pallets of the same SKU or lot together in one double-deep lane — rear position first, then front.
- Picking: pick the front pallet first; the rear pallet becomes accessible once the front one is removed.
- Slotting rule: assign fast-moving SKUs with many pallets to double-deep lanes and keep single-pallet SKUs in selective racking.
Forklift and aisle requirements
Typical working aisles for a reach truck with double-deep forks are 2.8–3.2 m between load faces, compared with 3.0–3.5 m for a standard reach truck in single-deep racking and 3.5–4.0 m for a counterbalance forklift. Counterbalance trucks cannot normally reach the rear position, so the forklift choice must be made together with the rack design.
Advantages and limitations
Advantages
- 30–40% more pallet positions than single-deep racking on the same floor, because roughly half of the aisles are removed.
- Lower cost per pallet position than drive-in, push-back or shuttle systems, since it uses standard beams and frames.
- Good selectivity for a dense system: 50% of pallets are directly accessible, and every lane holds only two pallets.
- Flexible and expandable: beam levels can be adjusted, and rows can be converted back to selective racking later.
- Fast throughput compared with deep-lane systems, as trucks never drive inside the rack.
Limitations
- Requires a reach truck with double-deep forks — an extra investment if your fleet is only counterbalance trucks.
- LIFO within each lane, so it is not suitable for strict FIFO or FEFO by individual pallet.
- Placing the rear pallet needs more operator skill; good lighting, height indicators or cameras help.
- Higher loads per bay mean the floor slab and anchoring must be verified.
Double deep vs selective, drive-in and push-back racking
| Criteria | Selective | Double deep | Drive-in | Push-back |
|---|---|---|---|---|
| Storage density | Base | +30–40% | +60–80% | +50–70% |
| Pallet accessibility | 100% | 50% direct | Lane by lane | Front pallet per lane |
| Stock rotation | FIFO / any | LIFO per lane | LIFO (drive-in) | LIFO |
| SKUs suited | Many SKUs, few pallets each | Medium SKUs, ≥2 pallets each | Few SKUs, many pallets | Few–medium SKUs, 2–5 pallets each |
| Forklift | Any | Reach truck with double-deep forks | Counterbalance / reach truck entering the lane | Any |
| Relative cost per position | Lowest | Low | Medium | Medium–high |
In practice, many warehouses combine systems: selective racking for slow, single-pallet SKUs, double deep for medium movers, and drive-in or push-back racking for a few very high-volume SKUs or cold storage.
When to choose double deep warehouse racking
- You run out of floor space but want to avoid the cost of shuttle or automated systems.
- Most SKUs have at least 2–4 pallets in stock at any time.
- Stock rotation by batch (not by individual pallet) is acceptable.
- You already use, or can invest in, reach trucks.
- The building is at least 7–8 m clear height, so density gains are multiplied by height.
Design and safety considerations
Double deep racking should be designed and checked to a recognised standard such as EN 15512 / FEM 10.2.02 or the RMI/ANSI MH16.1 specification, and installed, used and inspected in line with EN 15635. Key points during design:
- Load data: pallet size, maximum pallet weight and the number of levels — beams and frames are sized from these, with safety factors.
- Floor slab: check slab thickness, concrete grade and flatness for the point loads under each base plate.
- Flue spaces: keep the transverse and longitudinal flues clear for sprinkler performance and pallet overhang.
- Rear-pallet stops and supports at every level to prevent pushing pallets through the rack.
- Protection: column guards and end-of-aisle barriers where trucks turn.
- Load notices at every run, and a documented rack inspection routine: daily visual checks by operators, a monthly check by a trained person, and an annual inspection by a competent inspector.
How to calculate capacity
Capacity = number of bays × levels (including the floor level) × 2 pallets wide × 2 pallets deep. For example, a run of 20 bays with 5 levels holds 20 × 5 × 4 = 400 pallets. Compared with single-deep racking in the same footprint, you typically gain 30–40% positions once the removed aisles are counted.
What affects the cost of a double deep racking system?
Prices depend entirely on the layout, so Long Quyen quotes each project from your drawing. The main cost drivers are:
- Rack height and number of beam levels, which set the upright section and steel weight.
- Pallet weight and dimensions, which determine beam profile and span.
- Number of pallet positions and the length of each run.
- Finish: standard powder coating, or hot-dip galvanising for cold stores and humid areas.
- Accessories: row spacers, rear stops, mesh decking, column guards, end barriers and load signs.
- Site conditions: floor anchoring, working at height, phased installation in a live warehouse.
Remember to include the forklift in the total investment: if you need new reach trucks with double-deep forks, compare the full cost against the savings in floor space or rented warehouse area.
Installation process
- Site survey – measure the building, columns, doors, sprinklers and lighting; check the floor slab.
- Layout design – choose bay sizes, levels and aisle widths to suit pallets and trucks; issue 2D/3D drawings and load calculations.
- Manufacturing – roll-forming, punching, welding and powder coating of frames and beams at the factory.
- Installation – set out grid lines, erect and anchor frames, fit beams, spacers, stops and protection.
- Inspection and handover – check plumbness and beam locks, fit load signs, and train operators and supervisors.
A typical project of 500–1,500 pallet positions takes about 2–4 weeks from approved drawings to handover, depending on quantity and site access.
Maintenance tips
- Never exceed the load shown on the load notice; re-check it whenever pallet weights change.
- Report and unload any bay with a bent upright or damaged beam immediately.
- Check that beam locking pins are in place and anchors are tight during monthly inspections.
- Keep flue spaces and aisles clear, and train new reach-truck drivers on rear-pallet placement.
FAQ
How much more storage does double deep racking give?
Usually 30–40% more pallet positions than single-deep selective racking on the same floor area, because about half of the working aisles are removed.
Which forklift do I need for double deep racking?
A reach truck with telescopic double-deep (pantograph) forks, or a deep-reach truck. Standard counterbalance forklifts cannot normally place or retrieve the rear pallet.
Is double deep racking FIFO or LIFO?
Each double-deep lane is LIFO: the front pallet must be removed before the rear one. Store two pallets of the same SKU or batch in each lane to keep rotation simple.
How high can a double deep racking system be?
Most systems in Vietnam are 6–10 m to the top beam, limited by the reach truck lift height, building clear height and floor capacity.
What is the difference between double deep and drive-in racking?
Double deep stores two pallets in depth and trucks never enter the rack; drive-in stores many pallets deep and trucks drive into the lanes. Drive-in is denser but much less selective.
Can existing selective racking be converted to double deep?
Often yes, if frames and beams are suitable for the loads and you add row spacers, rear stops and suitable trucks. An engineering check of the existing racking is required first.
Get a double deep racking design from Long Quyen
Long Quyen has designed, manufactured and installed warehouse racking since 1997 – nearly 30 years and 500+ projects for factories and logistics centres across Vietnam. Our racking is produced under an ISO 9001:2015 quality system, with a warranty of 24–60 months depending on rack type and accessories. Send us your warehouse drawing for a free site survey and layout proposal: hotline 0903 422 179 or contact us online. See all double deep racking products and other pallet racking systems.
