When selecting and installing undermount drawer slides, specific measurements are critical to ensure proper fit and function. Unlike traditional side-mount slides, undermount slides attach to the underside of the drawer box and the inside of the cabinet, requiring precise interior drawer dimensions.
The primary measurements for undermount drawer slides involve the drawer box's dimensions, particularly its width and the thickness of its sides, in relation to the cabinet opening.
Key Undermount Drawer Slide Measurements
According to the provided reference, using undermount slides depends on the thickness of the drawer sides to be 1/2”, 5/8 or 3/4”, depending on the specific slide model. The critical measurements are the inside of the drawer.
For the most common undermount slides, you need the inside measurement of the drawer box to be 1 5/8” less than the face frame opening.
Here's a breakdown of the essential measurements:
- Drawer Box Side Thickness: This is crucial as the slide mechanisms fit snugly against the bottom outside edge of the drawer box sides.
- Common acceptable thicknesses are 1/2”, 5/8”, or 3/4”.
- Always check the specifications for the particular undermount slide you plan to use, as compatibility varies.
- Inside Drawer Box Width: This is perhaps the most critical measurement. It dictates the required clearance between the drawer box and the cabinet sides.
- For the most common undermount slides, the inside width of the drawer box must be 1 5/8” less than the width of the cabinet's face frame opening (or the clear opening between the cabinet sides for frameless cabinets).
- Calculation Example: If your cabinet opening is 18 inches wide, the required inside width of your drawer box would be 18 inches - 1 5/8 inches = 16 3/8 inches.
- Drawer Box Length: Undermount slides come in various lengths (e.g., 18", 21", 24"). The slide length determines the maximum drawer box depth. Measure from the back of the cabinet face frame (or front edge of the cabinet side for frameless) to the back of the cabinet. Select slides and build your drawer box depth accordingly (typically slightly less than the slide length).
- Drawer Box Height: While less critical for the slide function itself, the drawer box height must clear any obstructions within the cabinet and allow for the undermount slide mechanism beneath it.
Summary of Key Measurements for Undermount Slides
| Measurement | Requirement (Based on Reference) |
|---|---|
| Drawer Side Thickness | 1/2”, 5/8”, or 3/4” (depending on the slide) |
| Inside Drawer Box Width | 1 5/8” less than the face frame opening (for most common slides). This is a critical measurement. |
| Drawer Box Length | Match slide length (or slightly less) based on cabinet depth. |
| Drawer Box Height | Must clear obstructions and slide mechanism. |
Understanding these measurements, especially the 1 5/8” rule for inside drawer width and the requirement for specific drawer side thicknesses (1/2”, 5/8”, or 3/4”), ensures that your undermount slides fit correctly and provide smooth, hidden operation for your drawers. Always consult the specific manufacturer's instructions for precise requirements.
