Drawer slides come in two main mounting styles: side mount and under mount. Each has specific advantages for different drawer applications. The choice affects load capacity, drawer access, installation complexity, and cost.
Side Mount Characteristics
Side-mounted slides attach to the drawer sides and cabinet sides. They’re visible when the drawer opens, sitting in the gap between drawer and cabinet. Standard European-style side mounts are the most common type in ready-to-assemble furniture and older cabinets.
These slides typically support 75-100 pounds depending on quality and length. Heavy-duty versions handle up to 150 pounds. The load rating applies when the drawer is fully extended, which is important for accessing items at the back.
Under Mount Benefits
Under-mount slides attach to the drawer bottom and cabinet floor, hiding completely from view. This creates a cleaner appearance and gives you full use of the drawer interior width. The slides don’t intrude into the storage space.
Load capacity ranges from 75 pounds for basic models up to 100 pounds for quality versions. Some heavy-duty under-mount systems support 150 pounds, matching side-mount capacity. The rating depends on drawer length and slide quality.
Installation Complexity
Side mounts install faster and more forgivingly. Mark the height, screw the cabinet member to the cabinet side, and screw the drawer member to the drawer. Height adjustment typically allows 1/8 inch of play to correct minor errors.
Under mounts require more precision. The drawer must sit at exactly the right height relative to the cabinet, and the slides must be perfectly parallel. Most under-mount systems include adjustment screws for fine-tuning the fit after installation, but you need to start close to the target position.
Access and Extension
Both styles come in partial-extension and full-extension versions. Partial extension gives you access to about 75% of the drawer depth. Full extension pulls the drawer completely out, exposing the entire interior.
Under-mount slides more commonly include full extension as a standard feature. Side mounts often require a price jump for full-extension models. For deep drawers or cabinets, full extension becomes essential for reaching items at the back.
Cost Comparison
Basic side-mount slides cost $3-8 per pair. Quality European-style side mounts run $12-20 per pair. Under-mount slides start at $15-25 per pair for basic models and reach $40-60 for quality versions with soft-close features.
The price difference narrows when comparing similar quality levels. Heavy-duty side mounts with soft-close features cost nearly as much as comparable under-mount slides.
Soft-Close Features
Soft-close mechanisms slow the drawer in the last few inches of closing, preventing slamming. Both slide types offer this feature at higher price points.
Under-mount soft-close systems integrate more cleanly since the mechanism hides beneath the drawer. Side-mount soft-close adds visible components to the drawer sides, though this rarely matters functionally.
Application Guidelines
Use side mounts for:
- Budget-conscious projects
- Retrofitting existing furniture
- Shop cabinets and utility storage
- Situations where installation speed matters
Use under mounts for:
- Kitchen and bathroom cabinetry
- Furniture where appearance matters
- Face-frame cabinets needing full-width drawers
- Projects where you want drawers without visible hardware
Longevity Factors
Quality matters more than mounting style for longevity. Ball-bearing slides outlast roller slides regardless of mounting position. Look for steel construction rather than plastic components, especially on the load-bearing parts. Heavy-duty slides justify their higher cost in high-use applications.
