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Installing a new commercial door is a precise undertaking that takes a lot of careful measurement and proper selection to get right. 

If you don’t handle purchasing your new door carefully, you could find yourself with a door that doesn’t fit correctly. Should you be concerned if there’s a gap at the bottom of your door? It depends on the situation and how big the gap is.

Why Are Exterior Doors Tightly Sealed?

When you’ve installed a new storefront door or other exterior door for your business, there should be practically no gap between the door and the threshold. Your door, threshold, and frame should have been carefully selected and measured to ensure that no gap results.

You want your exterior door to provide an effective barrier, and a gap would prevent that. First, it would allow air to pass freely and create drafts, hampering cooling efforts in the summer and heating during the winter. You can also find yourself dealing with pests if a substantial gap exists.

Weather stripping can prevent those two issues but relying on weather stripping to cover a large gap can leave security concerns on the table. A large gap can allow intruders to put tools under the door, whether to try to reach a lock or to gain leverage for a brute force attack.

It’s clear that minimizing the gap is incredibly important for exterior doors, but what about interior commercial doors? Interior doors present a different set of concerns to which business owners must pay close attention.

Gaps Beneath Interior Doors

If you notice a gap beneath an interior door, that’s perfectly normal. In fact, it would be a cause for concern if there wasn’t any gap. Having a gap allows for the smooth opening and closing of the door, preventing scraping and wear of the door itself or the floor underneath. There are safety concerns to consider as well.

In general, the gap beneath an interior door will be between three-quarters of an inch and half an inch. This width depends largely on the type of flooring, as door frames are generally installed when the floor is unfinished. A standard door can have varying levels of clearance over different flooring types.

That’s something that is important to keep in mind when changing the type of floor. Moving from carpet to vinyl or vice-versa will change the height of your floor. Using the same door will now produce a different gap. In the worst-case scenario, the door simply won’t fit with the new floor. However, leaving too much of a gap is also an issue.

In fact, the allowable size of gaps underneath fire doors is defined by the National Fire Protection Association. Maximum gap size is set at three-quarters of an inch for interior doors. 

This sizing helps prevent the spread of fire and smoke within a building. Three-quarters of an inch is a sizable gap, so most interior doors will have gaps narrower than that maximum value.

More Reasons Why Gaps Beneath Interior Doors Are Needed

There’s another important reason why interior doors have gaps — they let air flow through when the door is closed. This permeability lets your company's HVAC systems effectively circulate air even when doors are closed. Otherwise, doorways would be airtight, and every room would be completely isolated from the others.

If your door has an uneven gap, then you could be dealing with a poorly installed door or uneven flooring. Flooring can shift over the years, especially if your business has suffered any form of water damage or even consistent high humidity. 

You can inspect door hardware to see if the door isn’t mounted properly, but it could be the floor that’s the issue.

If something is wrong, you might eventually find yourself with the door scraping the floor. Nobody wants that, so make sure to deal with diminishing or uneven gaps as soon as they’re noticed.

Make Sure You Get the Right Size Door

Choosing the right size door to fit your frame and maintain the appropriate gap is easy with CDF Distributors. You can get a quote online for all of your door and door hardware needs today.












September 23, 2022
Wayne Foreman