2024-01-05 6 min read Portland Garage Doors Team
# Size Measurement Guide: What Every Homeowner Should Know
Whether you're planning to replace an existing garage door, install a new opener, or just want to understand your garage door system better, accurate measurements are essential. This comprehensive guide will walk you through everything you need to know about measuring your garage door and opening correctly.
Getting your garage door measurements right is crucial for several reasons. A door that's too small won't seal properly, leaving gaps that let in weather, pests, and compromise security. A door that's too large simply won't fit and will require expensive modifications to your garage structure. Even small measurement errors can result in operational problems, premature wear, and safety issues.
When shopping for a new door, accurate measurements ensure you get the right product the first time, avoiding delays, additional costs, and the hassle of returns or exchanges.
The width measurement is perhaps the most critical. Measure the width of the garage door opening at the widest point, typically at the bottom. Take the measurement from the inside edge of one side jamb to the inside edge of the opposite side jamb.
For accuracy, take this measurement at three points: the bottom, the middle, and the top of the opening. In an ideal world, all three measurements would be identical, but older homes especially may have openings that aren't perfectly square. Use the smallest of the three measurements when ordering a door.
Standard residential garage door widths include 8 feet for single car, 9 feet for single car with extra space, 16 feet for double car, and 18 feet for double car with extra space. However, custom sizes are available if your opening doesn't match these standards.
Measure the height of the opening from the floor to the bottom of the header, which is the horizontal framing member above the door. Again, take measurements on both sides and use the smaller figure.
Standard residential garage door heights are typically 7 feet or 8 feet. As with width, custom heights are available for non-standard openings.
This measurement is crucial for the hardware that supports your door. Measure the distance from the edge of the door opening to the nearest obstruction on each side, whether that's a wall, a shelf, or other obstacle.
Most garage door systems require at least 3.75 inches of side room on each side, though some low-headroom systems may need more. Having accurate side room measurements helps ensure the right hardware can be installed.
Headroom is the space between the top of the door opening and the ceiling or any obstruction above. This measurement determines what type of track system can be used and affects opener placement.
Standard track systems require 12 to 15 inches of headroom. Low-headroom systems are available for garages with limited space above the door and may require as little as 6 inches, though these typically cost more and may have operational limitations.
Measure from the front of the opening (where the door will be) to the back wall of your garage. This determines how far the horizontal tracks can extend and affects the type of opener that can be installed.
The backroom should be at least equal to the height of the door plus 18 inches. For example, a 7-foot tall door would need at least 102 inches (8.5 feet) of backroom.
If you're replacing an existing door, you can usually match the current door size. However, it's still worth measuring the opening rather than just the door, as the original door may not have been the optimal fit.
When measuring an existing door, measure the door itself from edge to edge for width and from bottom to top for height. Compare these measurements to the opening measurements you took earlier.
Many garage floors have a slight slope for water drainage. This can affect the bottom of your door. Note if your floor slopes significantly and which direction. A professional installer can make adjustments to ensure a proper seal despite an uneven floor.
The type of door currently installed affects replacement options. Panel doors, roll-up doors, and one-piece tilt doors all have different track and hardware requirements. Switching from one type to another may require additional modifications to your garage.
If you're keeping your existing opener, measure its location and available clearance. Also note the drive type (chain, belt, or screw) and any existing wiring or power sources.
While taking basic measurements yourself is a good starting point, there are situations where professional measurement is important. Call a professional if your opening is significantly out of square, if you have unusual structural conditions, if you're unsure about any measurements, if you're considering a custom or specialty door, or if your garage has limited headroom or side room.
At Portland Garage Doors, we offer free in-home consultations where our factory-trained technicians will take precise measurements and help you select the perfect door for your home.
Taking accurate measurements is the first step toward a successful garage door installation or replacement. While the process may seem straightforward, there are many factors that can affect the final fit and operation of your door. When in doubt, consult with professionals who can ensure your new door will fit perfectly and operate reliably for years to come. Contact Portland Garage Doors today to schedule your free measurement and consultation.