LockDry Aluminum Decking: Pros and Cons
LockDry is an interlocking aluminum deck surface that sheds water through its joints when installed over properly designed, sloped framing. Its strengths include resistance to rot and low routine upkeep; its trade-offs include higher upfront cost, temperature-related movement, possible heat, noise, and slippery conditions. Performance depends on sound framing, correct drainage, compatible fasteners, and careful installation.
If you have narrowed your remodel choices to a few materials, the next achievement is matching the surface to the conditions it must handle. LockDry may suit a raised deck where water needs to pass through the surface and away from the space below. It is not a simple finish to lay over a concrete slab, nor does it replace the work of designing a sound frame and drainage system.
I evaluate aluminum decking by looking beyond the plank itself. The support structure, slope, edges, fasteners, and water outlet all affect performance. The product’s current installation guide and project-specific structural design should settle exact spacing, load limits, and installation details.
What LockDry aluminum decking is
LockDry is an interlocking aluminum deck surface made of mechanically fastened planks. The joints are designed to shed water through the deck, so the system needs a planned route for that water to drain. It is a deck assembly, not a tile-like covering or a stand-alone waterproofing membrane.
The interlocking appearance can provide a clean, continuous look, while the metal surface does not rot like wood. Still, “water-shedding” does not mean that every area below will stay dry in every condition. Water control depends on slope, joints, flashing, edges, and the route water takes once it passes through.
Where it can and cannot go
LockDry is intended for compatible deck framing. Do not assume it can be fastened directly to an ordinary concrete slab. A concrete-supported project would need a separately designed frame and drainage detail, plus suitable anchorage and corrosion isolation.
Nor should the decking be treated as a substitute for structural waterproofing at a wall, door, or below-deck ceiling. Those areas need their own suitable details. Check the current product instructions and local requirements before deciding whether a particular layout is compatible.
LockDry decking pros and cons
The main benefits are a durable, non-rotting deck surface, an interlocking appearance, and low routine maintenance. The main drawbacks are higher initial cost than many wood or composite choices, metal’s temperature and sound behavior, and the need to manage drainage, movement, and corrosion carefully.
| Factor | Potential advantage | Trade-off or condition to check |
|---|---|---|
| Rot resistance | Aluminum does not rot like wood | Framing and other deck components still need inspection |
| Water management | Joints can shed water through the surface | Slope, edges, flashing, and outlets must be detailed correctly |
| Appearance | Interlocking planks can create a concealed, consistent look | Confirm the finish, color, and edge details suit the project |
| Upkeep | Routine care may be limited to cleaning and inspection | Leaves, algae, ice, and other contaminants still need removal |
| Comfort | A firm metal deck surface | It can feel hot or cold and may transmit impact noise |
| Cost | Long-term value may matter to some owners | Compare full installed system cost, not plank price alone |
Advantages that matter in daily use
A surface that does not rot can reduce one common concern associated with wood decking. Its water-shedding design may also help protect the area below when the complete system is installed and detailed as intended. That benefit depends on where the water exits and whether the lower area has its own protection needs.
Routine care is not the same as no care. The deck still needs cleaning, seasonal checks, and clear drainage outlets. I recommend judging low maintenance as a reduction in some surface-care tasks, not as freedom from inspection or repair.
Drawbacks to weigh before choosing
Aluminum can feel hot in sun and cold in cool weather. It may also sound different underfoot from wood or composite, as metal can transmit impact noise. These effects depend on site conditions and the deck assembly, so consider exposure and nearby rooms when evaluating samples or installed examples.
Wet or contaminated aluminum can be slippery, especially when leaves, algae, or ice are present. Do not apply a tile slip rating to this deck system. Ask for product-specific slip information, then consider the actual location and how the deck will be used.
Framing, slope, and drainage requirements
The deck frame is the structure that supports the walking surface and transfers loads to beams, posts, and connections. Before ordering, verify that the framing is sound and designed for both local code requirements and the product’s published span and load limits. A strong-looking plank does not establish a safe joist span.
Begin by checking joists, beams, posts, ledger, connections, and bearing points. Look for decay, splits, corrosion, and weak or inadequate fastening. Repair or replace problems before covering the frame; concealed defects can be harder to inspect later.
Next, confirm joist spacing and plank support against the current LockDry tables for the chosen product and use. Do not infer a permitted span from plank width or appearance. Do not substitute tile deflection rules such as L/360 or L/720 for the manufacturer’s span data. Design the frame for the applicable local code and product limits together.
Slope must follow the requirements for the selected assembly, in the direction water needs to discharge. There is no safe generic slope to insert without checking the current guide. Also confirm that wall and ledger flashing, perimeter details, and drainage outlets direct water away from the building rather than trapping it at a threshold or edge.
Installation details that affect performance
Installation uses the specified joists, clips or fasteners, plank orientation, end-joint support, and edge components. The frame should provide a consistent plane; forcing interlocking planks into line over uneven framing can create poor fit. Follow the current instructions for every spacing, fastening, and termination detail.
Blocked plank ends or incorrect fastening can restrain that movement. The result may include buckling, noise, joint disengagement, or fastener damage. Keep the required movement clearances and follow the specified fastening sequence; do not improvise to make a tight edge fit.
Use only the prescribed fastener type, spacing, and embedment. Aluminum can corrode through contact with incompatible metals or treated lumber if the required isolation detail is missing. Check the manufacturer’s guidance for compatible materials and any specified separation method.
At walls, stairs, fascia, and transitions, install the designated components and preserve drainage paths. A door threshold or adjoining surface must not dam water or trap debris. The deck surface alone does not waterproof these junctions.
Example project scenarios
These scenarios are illustrative, not reports of completed installations. They show how I would assess common project conditions before recommending a material or ordering planks.
Raised deck above a patio
A homeowner wants the area below a raised deck to receive less rain. LockDry may be worth evaluating because its surface is designed to shed water through its joints. First, verify that the frame can support the selected system, then confirm slope, flashing, perimeter details, and a clear discharge route.
The key question is not simply whether water passes through. It is where the water goes and whether the lower area needs additional protection. If the project requires a dry, enclosed room below, do not treat the deck surface as a complete waterproofing system.
Existing deck with questionable framing
A remodeler plans to cover an older deck but has not checked joist spacing, fasteners, or the ledger. The first step is inspection, not material ordering. Any decayed, split, corroded, or poorly secured framing needs attention, and spacing must match current product tables and structural design.
Covering a weak frame can hide problems without correcting them. If the framing cannot meet the required support and load limits, repair or redesign it before installation.
Concrete patio or slab
A homeowner considers fastening the aluminum planks straight to a patio slab. That is not a direct-to-concrete flooring application under the guidance used here. A separately designed support frame would need to address anchorage, drainage, slope, and corrosion isolation.
If the project cannot accommodate that assembly, compare other surfaces designed for the slab rather than assuming the deck planks can serve as a tile-like finish.
Is aluminum decking the right choice?
Use this decision table to compare the project’s needs with the main trade-offs. It is a screening tool, not a substitute for a structural review or current product instructions.
| Project condition | What to verify | Initial assessment |
|---|---|---|
| Raised deck with a planned water outlet | Slope, edge details, flashing, and discharge location | Potentially suitable if the full system is designed correctly |
| Existing frame of unknown condition | Joist spacing, span, connections, and visible damage | Inspect and repair before choosing or ordering |
| Deck exposed to strong sun or cold | Surface comfort and expected exposure | Consider temperature behavior before committing |
| Walkway near leaves, algae, or ice | Cleaning access and product-specific slip information | Plan regular cleaning and assess site safety |
| Concrete-only surface | Approved support system, anchorage, and drainage | Not a direct-to-slab installation |
| Area needing complete waterproofing | Separate wall, threshold, and below-deck water-control details | Do not rely on the decking alone |
A practical next step is to request the current installation guide, span and load tables, finish-care instructions, and product-specific slip information. Then compare the complete installed cost, including framing work, fasteners, edge components, and drainage details, with alternatives.
Maintenance and final verdict
Keep the surface and drainage outlets free of leaves, algae, ice, and other buildup. Clean only with methods and products allowed by the manufacturer. Avoid abrasive tools, aggressive chemicals, and incompatible metals that could damage the finish or increase corrosion risk.
Inspect seasonally and after severe weather. Check fasteners, end joints, flashing, drainage, coating damage, and signs of movement. A small problem at an edge or outlet can affect water management even if the planks still look sound.
LockDry is most compelling when a homeowner wants an interlocking aluminum deck surface and can provide compatible, well-designed framing and drainage. Its advantages do not remove the need for careful design. The decision should turn on the full assembly, not just the plank’s durability or appearance.
Frequently asked questions
These short answers address common buying and planning questions. Product-specific dimensions, clearances, and load limits can change or depend on the selected assembly, so confirm them in the current LockDry instructions and project design.
Does LockDry aluminum decking keep the area below completely dry?
Not by itself. It sheds water through its joints, but below-deck protection depends on the complete design, including slope, edges, flashing, and water discharge.
Can LockDry be installed directly over concrete?
Do not assume so. It is not a direct-to-concrete flooring system; a separately designed support frame and drainage detail would be needed.
What joist spacing should I use?
Use the exact spacing and load table for the selected product and use. Do not guess or rely on a spacing taken from another decking material.
Does the deck need a slope?
Follow the slope specified for the chosen LockDry assembly and direct water toward its intended outlet. Check the current guide rather than using a generic value.
Will aluminum decking expand in heat?
Yes. Aluminum expands as temperature rises. For a 20-foot plank, a 100°F temperature change corresponds to about 0.31 inch of length change; installation clearances must follow the product instructions.
Can the planks become slippery?
Yes. Wet or contaminated aluminum can be slippery, particularly with leaves, algae, or ice. Use product-specific slip information and keep the walking surface clean.
Is LockDry maintenance-free?
No. It still needs cleaning and inspection. Keep outlets open and check fasteners, joints, flashing, corrosion, and movement.
Can I use ordinary screws or fasteners?
Use the fastener type, spacing, and embedment specified for the system. Also follow instructions for isolating aluminum from incompatible metals and treated framing.
Is LockDry suitable for a deck above a patio?
It may be considered where water can drain through the joints and away from the building. Confirm the frame, slope, flashing, perimeter details, and needs of the space below.
What should I check before ordering?
Inspect the frame and verify joist spacing, span, bearing, connections, design loads, slope, and the water-discharge route. Review the current installation guide and local structural requirements.
(This article was written by one of our staff writers, Michael Roberts. Visit our Meet the Team page.)
