Hide Tools in Storage Workbenches (Undermount Trays)
A concealed undermount tray can keep small tools close at hand while leaving the work surface clear. Plan its full travel, check for wiring and knee-space conflicts, and support the slides from framing or a reinforced mount. Choose slides by their published instructions and load rating, then test the finished tray before placing tools inside.
A well-made tray can make a workbench more useful without changing its visible shape. That may help preserve the bench’s appeal if you later sell or refit your shop, but poor fit can do the opposite: sagging slides, blocked access, or a conspicuous gap can make a custom feature look like a repair. Plan it as part of the bench, not as an add-on.
I start by emptying the bench and mapping what lies beneath it. Then I choose a tray size, slide, and support method that fit the actual structure. The guidance below uses practical project targets, not building-code dimensions. There is no generally applicable IRC or IBC tray size or load rating for a workbench.
Plan the Tray and Survey the Workbench
A tray plan should account for the bench frame, stored tools, and anything beneath the work surface before you cut material. Measure the available opening and the intended tray envelope, including its full travel. Treat the stated dimensions in this guide as design targets, then follow the slide maker’s instructions when they differ.
- Empty and inspect the bench. Find the apron, legs, stretchers, screws, outlets, cords, wiring, and any mounted equipment. Use a light and inspect from more than one angle. Do not assume the underside is clear because it looks open from the front.
- Mark the tray envelope. Measure width, depth, and height, plus the space the tray occupies when closed and fully open. Check for clamps, vises, machine parts, and stored items that could collide with it.
- Choose what the tray will hold. A shallow tray suits small hand tools and accessories. A tray carrying heavier tools needs a suitable slide rating and sound support. Group likely contents and estimate the total weight before selecting hardware.
For shallow storage, a tray depth of 2½ inches maximum is a practical target, not a rule. Check that each tool fits and cannot touch wiring, machinery, or moving parts. A ¾-inch nominal cabinet-grade plywood bottom is also a practical starting choice, not a code minimum. Its suitability depends on tray size, support, and the intended load.
Write down the planned total service load, meaning the combined weight of the tray and its normal contents. Choose full-extension undermount slides with a published rating at least twice that planned load as a conservative design target. This is not a universal standard. The product rating applies only under the slide maker’s stated mounting and installation conditions.
| Design check | Practical target | What must take priority |
|---|---|---|
| Tray depth for shallow storage | 2½ in. maximum | Tool fit and clearance from hazards |
| Moving clearance at non-hardware edges | ⅛ in. minimum | Slide maker’s specified clearances |
| Tray bottom | ¾-in. nominal plywood | Size, reinforcement, and intended load |
| Slide capacity | At least 2× planned total service load | Published rating and installation conditions |
A small sketch helps catch conflicts early. Mark the tray, slide locations, fasteners, and nearby utilities. Keep the plan and slide instructions with the bench so the intended use and load limit are clear later.
Confirm Access, Travel, and Utility Clearances
Clearance is the space needed for the tray to move and for people, cords, and equipment to remain safe. Check the whole path, not only the closed position. The tray must be reachable without blocking comfortable standing or seated access, and it must not cover electrical boxes or interfere with disconnects or service access.
Pull the tray’s outline forward on your sketch to represent its fully open position. Check knee and leg room, nearby drawers, vise handles, doors, and the path you use to stand at the bench. A tray that opens smoothly on an empty bench may still obstruct your normal work stance.
Keep the tray clear of outlets, cords, wiring, and equipment. Do not cover electrical boxes, block access to disconnects, or obstruct ventilation openings. If electrical equipment or wiring is affected, follow the locally adopted electrical code. NEC 110.3(B) applies to listed equipment installed and used according to its instructions. Access and wiring-protection rules depend on the installation and local code.
If you cannot confirm a safe route around wiring or equipment, move the tray plan rather than guessing. Do not use a tray as a cover for a cord or electrical box. When a change affects a listed electrical product or fixed wiring, consult the product instructions and the authority or qualified trade professional responsible for that work.
For the slides, note the required side spacing, vertical position, setback, and fastener type from the installation sheet. A general clearance target cannot replace a product’s template. Leave at least ⅛ inch at non-hardware edges as a project target, unless the slide maker specifies another dimension.
Before cutting, make a simple full-size cardboard or scrap-wood mock-up. Hold it in the planned position and move it through the full travel. This quick check can reveal a knee-space or equipment conflict before it becomes a finished-wood problem.
Reinforce, Install, and Finish the Tray
Undermount slides carry force through their mounting points into the bench. An apron or thin benchtop edge is not automatically strong enough. Attach slide members to framing or a properly reinforced mount, and follow the selected product’s spacing, setback, and fastening instructions rather than relying on a generic layout.
A reliable build sequence is:
- Prepare the support. Identify solid framing at both slide locations. If the existing apron is too thin, weak, or poorly placed, add a supported mounting frame that transfers the load into the bench structure. Do not rely on short screws in unsupported plywood or particleboard.
- Build the tray square. Cut the bottom and sides to suit the slide system’s required dimensions. Use the ¾-inch nominal plywood bottom only if it suits the span and planned load. Add side or bottom reinforcement when the tray design and hardware call for it.
- Install the slides. Use the maker’s template or measurements for setback, spacing, and fasteners. Keep the slide members aligned and level as specified. A small alignment error can cause binding or uneven movement.
- Fit the tray empty. Engage the slides and cycle the tray through its full range. Correct rubbing or binding before loading. Do not force a tray that catches; check alignment, clearances, and fasteners.
- Finish and secure contents. Ease sharp exposed edges and apply a finish suited to the shop environment. Add dividers or a low restraint where tools could shift during opening and closing.
I have found that a clean-looking closed front starts with accurate alignment, not with decorative trim. A face or front rail should not hide a slide problem or prevent you from removing the tray for service. Keep the seam even, but preserve the clearance the slide needs.
Worked installation examples: These are planning examples, not claims about tested load capacity. For a small hand-tool bench, a shallow tray can hold frequently used items if the tools fit, the slides meet the planned-load target, and the support reaches the frame. For a bench with a vise or machine below, the better solution may be a narrower tray or no tray at that location. In both cases, mock up the full travel before drilling.
Keep a record of the slide model, installation instructions, and intended maximum load. This is useful if you later adjust the bench, replace hardware, or sell the workbench with its custom storage.
Verify Load, Operation, and Ongoing Safety
A completed tray is ready for use only after you check its support, travel, and clearances under a controlled load. The slide’s published capacity depends on its product and installation, so do not treat a successful hand test as a replacement for the maker’s rating or instructions.
Start with the empty tray. Open and close it several times, watching for rubbing, shifting, or uneven gaps. Recheck that the slides and fasteners remain secure. Then add a small portion of the planned load, spread it across the tray, and cycle it again. Increase the load in steps only up to the documented intended service load.
Stop and inspect if the tray sags, binds, pulls a fastener, or changes alignment. Remove the contents before adjusting the slides or mount. Do not exceed the published slide rating, and do not assume that a higher rating compensates for weak bench framing.
| Test | Pass condition | If it fails |
|---|---|---|
| Empty travel | Full movement without binding or collision | Check alignment and clearances |
| Loaded travel | Smooth movement at intended service load | Reduce load; inspect support and slides |
| Closed position | Tray clears tools, wiring, and equipment | Rework location or tray size |
| Mounting | Fasteners remain secure; no visible movement | Unload and reinforce the support |
| Access | Outlets, disconnects, and service areas remain reachable | Relocate or remove the tray |
Recheck fasteners and clearances after the first period of regular use, and whenever you change the tray’s contents or the bench layout. Keep tools from shifting by using dividers or a restraint that does not interfere with slide movement. The key test is not whether the tray can close once, but whether it remains supported and unobstructed in its intended use.
Conclusion and FAQ
A concealed tray works best when it is sized for real tools, supported by the bench frame, and clear of utilities throughout its travel. Use the slide maker’s dimensions and load instructions, document the intended load, and test in stages. If the structure or electrical clearances are uncertain, revise the layout before installation.
How deep should an undermount workbench tray be?
For shallow storage, 2½ inches maximum is a practical design target. Confirm that tools fit and cannot contact wiring, equipment, or moving parts.
What plywood thickness should I use for the tray bottom?
¾-inch nominal cabinet-grade plywood is a practical starting choice. It is not a code minimum; tray size, support, and intended load determine whether it is suitable.
How much load should the slides support?
Use full-extension undermount slides with a published rating at least twice the planned total service load as a conservative design target. Follow the product’s installation instructions and rating conditions.
Can I mount slides directly to the bench apron?
Only if the apron and its connection to the bench provide suitable support for the intended load. An apron or thin benchtop edge is not automatically adequate. Reinforce it or mount to framing when needed.
What clearance should I leave around the tray?
Use at least ⅛ inch at non-hardware edges as a project target, but follow the slide maker’s specified side, vertical, and setback dimensions wherever they differ.
Can the tray sit below an outlet or wiring?
Do not cover electrical boxes or obstruct wiring, disconnects, or required service access. Keep the full tray path clear. Local code requirements depend on the installation.
Why does an undermount tray bind?
Common things to check include slide alignment, spacing, setback, and collisions along the travel path. Compare the installation to the slide maker’s template and correct the cause rather than forcing the tray.
Should I test the tray before adding tools?
Yes. Cycle it empty first, then add weight in steps up to the intended service load. Stop if it sags, binds, shifts, or loosens.
Do I need to document the tray’s load limit?
It is useful to record the slide model, its instructions, and the tray’s intended maximum load. That gives you a clear reference if the bench is changed or used by someone else.
(This article was written by one of our staff writers, Nathaniel Pierce. Visit our Meet the Team page.)
