How to Choose the Right Sill for Your Bi-Fold Door

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When you're installing a bi-fold door, the sill is one of the most important features you need to think about. The sill provides protection from the weather elements, and it affects the look and accessibility of your living area. Not sure how to choose the best option? Here are some things to consider before making your decision.

Types of sills

There are two main types of sills for bi-fold doors: a raised (standard) sill or a recessed channel (flush sill). The raised sill offers the best protection against wet weather because it elevates above the floor level and creates a barrier that prevents the water from coming in. Additionally, this type of sill has a system of weep holes to drain away the water from the bottom area. However, the raised sill is more visible, and you will need to step over it.

The flush sill creates an unobstructed transition between the two spaces. It makes your space look bigger and there is nothing to trip over. At the same time, it is less weather-resistant, and some water or air can come under the door. 

Weather exposure

The main factor to keep in mind when choosing your sill is the location of your bi-fold door and how exposed it is to the elements. If the door connects your house with the outside, you want to make it as water and airtight as possible, so the standard sill will be the better option.

If your bi-fold door is between two inside areas or opens up into a sheltered space, then waterproofing your door may not be as important, and you may prefer a recessed channel. A flush sill looks great between the play area and the living room, and it reduces the risk of accidents as children play.


If someone in your home uses a wheelchair or has difficulty stepping over high thresholds, you must take this into consideration when deciding on the height of your sill. You can make your raised sill more wheelchair-friendly by sinking it below the floor level to achieve a more leveled entrance.  If the door is for a new house, this is something you can discuss with your builder and if you're replacing an old door, it may be necessary to remove a layer of bricks to make room for the sill. Another option that can help you increase accessibility is to add a threshold ramp.