Let the Light In! Precisely Calculating Rough Openings for French Doors
French doors are known for letting abundant natural light into a space while also providing an indoor-outdoor feel. Their row of glass panes blurs the line between interior rooms and outdoor living areas. But to fully enjoy their benefits, French doors need to be properly installed within a rough opening that is just the right size.
Calculating the accurate rough opening dimensions is a crucial first step in any French door installation. If the measurements are off, you could end up with doors that swing improperly, gaps around the frame, or hardware that doesn't line up. Getting it right takes careful planning and calculations.
Determining the Correct Width
The first key measurement is calculating the total width of the rough opening based on your actual French door size. Here are the steps:
- Measure the width of one door panel from side to side. For standard sizes, this is often 36".
- Multiply this individual width by 2, as you will have two door panels swinging from the frame.
- To this total, add at least 2" of clearance space all around.
This extra width accommodates shims during installation, provides room for the doors to freely swing open without obstruction, and allows adjustment space.
For example, if each of your French door panels is 36" wide, you would calculate:
- 36" door panel width x 2 door panels = 72" total width
- Plus 2" clearance = 74" rough opening width
Determining the Correct Height
For the height, a similar process is followed:
- Measure from the bottom to the top of one door panel to get its height.
- Multiply by 2 for the total height of both doors.
- Add 2 1/2 - 3" for header space and clearance above.
This headroom lets the doors swing freely and provides space to lift and position them during installation. A standard door height is 80". So for a typical setup:
- 80" door panel height x 2 = 160"
- Plus 2 1/2" clearance = 162 1/2" total rough opening height
Accommodating Other Essential Details
When sizing the rough opening, you also need to consider other factors like weatherstripping, hardware, door swing direction, and the door material itself.
Weatherstripping Needs
The rough opening must have adequate clearance around the perimeter for effective weatherstripping. Tight compression seals not only prevent drafts, but also stop air leaks, moisture, dust, and pests. They can lower energy costs too. Make sure to account for the extra space weatherstripping requires when calculating width and height.
Hardware and Locks
Determine if any specialized hardware or locks will be installed with the French doors. Oddly shaped handles or multi-point locking mechanisms may necessitate tweaking the rough opening size to ensure everything fits and functions properly. Pay attention to the measurements and clearance needed around handles and lock boxes.
Door Swing Direction
Consider which direction the doors will swing when open. Outward swinging doors require more space in front for the arc of the swing. Inward swinging doors can have a slightly narrower rough opening. Factor this into your width measurement.
Material Thickness
French doors come in various materials like wood, fiberglass, or vinyl. Thicker wooden doors often need a wider rough opening than more slender vinyl models. The door material's thickness must be taken into account.
Verifying the Rough Opening
Once you have carefully measured and calculated the rough opening size, verify that:
- The opening is perfectly plumb and level.
- The header and studs are properly positioned.
- The measurements match the manufacturer's specifications (if provided).
- Do a test fit by taping the opening off and fitting the doors inside.
This dry run can reveal any issues to adjust before the full install. Pay attention to gaps, alignment, swinging clearance, and hardware placements.
French doors need properly framed and sized rough openings to function and look their best. Now that you know how to accurately calculate the right width, height, clearances, and considerations, you can install French doors confidently. Just follow manufacturer guidelines for your specific products too.
Taking the time to measure and size the rough opening precisely leads to years of smooth operation and enjoyment. Your new French doors will elegantly let the light flood into your home. Enjoy the indoor-outdoor living feel you've always dreamed of!