To measure the rough opening for a patio door, you need to determine the width and height of the structural opening in the wall where the door will be installed. This opening is framed by studs, a header (lintel), and a subfloor or sill plate.
The rough opening measurements are typically slightly larger than the actual door frame dimensions to allow for shimming and insulation.
Steps to Measure Rough Opening
Follow these steps to accurately measure the width and height of your patio door rough opening:
Measuring the Width
The rough opening width is the horizontal distance between the inner faces of the framing studs on either side of the opening.
- Locate the studs: Find the framing studs on the left and right sides of the opening.
- Measure across: As demonstrated in the reference, place the beginning of your measuring tape on the inside face of one stud frame.
- Extend tape: Pull the tape measure straight across the opening until it reaches the inside face of the opposite stud frame.
- Record measurement: Note this measurement down.
- Measure in multiple spots: Measure the width at the top, middle, and bottom of the opening. The smallest measurement is usually the most critical, as it represents the narrowest point the door frame must fit through.
Measuring the Height
The rough opening height is the vertical distance from the underside of the header to the top of the subfloor or sill plate.
- Locate header and subfloor: Identify the header beam at the top of the opening and the subfloor or sill plate at the bottom.
- Place tape: According to the reference, place the beginning of the measuring tape on the header.
- Extend tape: Extend the tape measure straight down to the subfloor.
- Record measurement: Note this measurement down.
- Measure in multiple spots: Measure the height on the left side, in the center, and on the right side of the opening. Again, the smallest measurement is important.
Key Measurements
| Measurement Type | Start Point | End Point |
|---|---|---|
| Width | Inside face of one stud frame | Inside face of opposite stud frame |
| Height | Underside of the header | Top of the subfloor |
Important Considerations
- Accuracy is key: Measure precisely to the nearest 1/8 inch.
- Multiple measurements: Always measure width and height in at least three different locations (top, middle, bottom for width; left, center, right for height) and use the smallest measurement. This ensures the door will fit the narrowest point.
- Check manufacturer specifications: Door manufacturers provide recommended rough opening sizes for their specific doors. Compare your measured rough opening to the manufacturer's requirements to ensure compatibility. The rough opening is typically 1/2 inch larger than the door frame width and height to allow for shimming.
- Measure structural opening: Ensure you are measuring the wood framing opening itself, not any trim, drywall, or exterior siding.
By carefully measuring the width and height as described, paying attention to the lowest recorded values and comparing them to the door manufacturer's specifications, you can determine the appropriate rough opening for your patio door installation.
