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How Does A Glass Replacement Door Fit Into My Existing Fireplace?

Fireplace Door Fit InfographicInstalling fireplace doors over uneven surfaces or within your firebox will depend on the type of application you have. Some fireplace doors are available as an overlap fit, while others comes as an inside fit door. Some of these are suitable for zero clearance fireplaces, while others are best utilized on masonry applications. There are some doors that can be used on both fireplace styles; however, there will be differences in the outside measurements, even if the design and glass size are the same. Let's see if we can put this into perspective for you!

There are three main door fit styles available. For illustration purposes of the following information, click on the infographic (shown at right)!

  1. Overlap Fit Fireplace Doors
    This means that the door frame is wider so that it will sit over your fireplace surround. The extra frame width is designed to conceal the edges of the fireplace opening. Otherwise, there would be the possibility of the facing showing through the glass or the presence of gaps around the outside of the door. This fit style is highly recommended for masonry fireplaces!

  2. Inside Fit Fireplace Doors
    The inside fit is more narrow so that it can slide into the firebox opening. Your fireplace surround - be it brick, slate, stone, rock, or ledgestone - will overhang the door. It can be used with both zero clearance and masonry applications, but it is better suited for the zero clearance fireplace.

    • FOR MASONRY FIREPLACES: The inside fit door slides inside the firebrick and will need to be mortared in to hide any gaps around the frame. Ultimately, your fireplace surround will be flush with the door and look more like a zero-clearance fireplace. 
  3. Cutback Fit Fireplace Doors
    Essentially, this is a modified-overlap fit and not utilized as much as the overlap and inside fits. A slight protrusion of the frame is present (with the outermost part overlapping the lintel), while the remainder of the frame fits inside the firebox. This is recommended with masonry fireplaces only.

Regardless of how your replacement fireplace door will correspond to your application, it is imperative that we have the exact measurements of your existing fireplace opening so that your door can be tailor-made to conform to the firebox. Look at the example below:

Would an inside fit or overlap fit door work best for this fireplace?

If this was your fireplace and you were seeking to update or replace the doors, you would need to measure the width and the height at the most narrow points in the opening. In this case, the dimensions are 30" wide by 25" tall. (Always measure the most narrow area so that the fireplace door can easily slide into the firebox.)  

If I have a rock or ledgestone surround and choose an inside fit door - won't there be gaps between my door and my surround?

Yes! Masonry fireplaces are constructed of a substrate material that is not always even or smooth. Gaps are quite common when installing a replacement inside fit door. Therefore, this particular style will need to be mortared in with high-temperature concrete. You must be careful to keep the mortar off your new door, because this material can discolor it. This is one of the reasons that we highly recommend overlap fit doors for masonry fireplaces. 

If you decide to opt for an inside fit door, we'd like to show you what we mean by "gaps" and "mortaring in." Below you can see how stone and rock surrounds can leave small to large gaps between the door frame and the surround, and how that can be fixed with mortar.

Ledgestone inside fit fireplace door example

With proper measuring and appropriate mortaring in, your fireplace door surround will look as if it was built around your new inside fit door!

What if I have a rock or ledgestone surround and choose an overlap fit door - will there be gaps between my door and my surround?

Yes, that is entirely possible, depending on the texture and depth of the peaks and valleys in the rock surround. There are a couple things that can be done to help with this. The first solution is to skip the "standard" doors and opt for one of our custom models. This will allow us to better fit your new glass door to your fireplace. We can create a thicker custom framework that will help to cover any potential gaps. Another option is to place specialized fireplace insulation into these voids. Of course, you can always elect to mortar in the gaps as you would with inside fit doors: 

Inside fit fireplace door with large rock surround.

In order to find the right door for your masonry fireplace, we highly recommend giving our fireplace door experts a call so that we can help you through the process of properly measuring and selecting the best model!