A Deep Dive Into Patio Door Vocabulary

A Deep Dive Into Patio Door Vocabulary

Whether you’re planning renovations or just daydreaming, trying to navigate patio door terminology can make your head swim! If you feel like you’re drowning in terms such as “IGU” or “mortise,” then take a glance at this vocab lesson to get yourself on solid ground.

Terms and components of a patio door


The frame is the main structure supporting the patio door. You can choose from PVC or hybrid (PVC covered in aluminum) frames, or even fully aluminum frames if you’re looking for a higher-end product.

PVC is a versatile and energy-efficient material with the highest quality-to-price ratio on the market, as demonstrated by our 630 patio door.

Our aluminum patio doors boast sturdy construction, a timeless appearance and superior energy performance thanks to efficient thermal breaks (PVC inserted between the two aluminum structures). They adapt well to any interior thanks to their many configurations, and when it comes to painting, aluminum is the premier choice for colours that really last.

Finally, our hybrid patio doors combine the best of both worlds, with economical PVC and elegant aluminum, and come in five standard colours.

Sill and sill cover

The sill is the horizontal piece that the patio door slides on, located above the frame at the bottom of the door. In general, the greater the slope of the sill, the better the drainage.

Our quick draining sills with integrated 9° slope help keep your door airtight and watertight and prevent ponding. The sill cover improves the finish and makes maintenance easier by protecting the sill from dirt and damage. The cover is attached to the sill and made from anodized aluminum for better resistance.

Fixed panel or opening panel

The panel is the detachable part of the patio door. The fixed panel is held in place on the sill, while the open panel slides out and opens up. Our patio doors come with a wide range of possible configurations of fixed and open panels to better suit your needs.

Transoms over a patio door

Transoms and sidelites

Both transoms and sidelites are windows placed around a patio door: transoms just above the door and sidelites alongside it. These features help suffuse a room with natural light. We offer our patio doors with a wide selection of custom transom and sidelite configurations to work with all kinds of sizes and styles.

Insulated glass units

Insulated glass units (IGUs) are composed of two hermetically sealed panes of glass, with the space between them filled with argon gas to better insulate the window. All of our patio doors come with high-performance IGUs, but if you want to go the extra mile when it comes to energy efficiency, we also offer the option of triple-sealed glass on most of our patio doors.

Low-E glass

Low-E (low-emissivity) glass is glass that has been coated with an invisible layer of energy-efficient material. It lets in outdoor light but keeps the heat in, reducing your home’s winter heating costs.

In some cases, depending where the low-E coating has been applied on the IGU, the material can also reflect heat from outdoors away from the window to keep the room at a comfortable temperature.

It’s important to think carefully about where to put your low-E window. Energy-efficient low-E glass that faces due south could end up overheating the inside of your house so that it’s no longer comfortable by the end of the day. Low-E glass is also a great choice to help you meet the criteria required for the Energy Star program.


The mortise is the part of the handle that locks the patio door, often in the form of a small hook. The more mortises a handle has, the better a job it does at locking. For example, our Studio handle has the distinction of featuring a double-point locking system. Take a look at how it works with our Urbania patio door. There are even triple-point mortise systems, like our lift and slide Kora handle, which comes with the unbeatable Loft patio door. With this kind of unparalleled security, you’re sure to sleep soundly!