To measure your fireplace, you’ll have to record the height, width, and thickness.
Failing to note the dimensions can lead you to buy an insert that won’t fit correctly.
To do this, you’ll have to record each measurement at several points for an accurate reading.
Fireplace opening, firebox, or cavity, it is all the same! These terms refer to the same thing.
Now the speedy means is to take the right width and the height of the fireplace and call it a day, right?
Wrong! To pull the right dimensions, you have to measure your fireplace cavity at several points to ensure that there aren’t any parts that are smaller than others.
Using measuring tape, note the height of your firebox from the opening, the back, and the lintel. If you own a fireplace with an arched opening, make sure you take down the measurements at the highest and lowest points. You need to use the smallest of those measurements for your final report.
Some brick fireplaces have what’s known as a lintel. A lintel is an iron rod that runs from front to back down the ceiling of your fireplace opening.
The lintel function is to provide structural support for your fireplace and is usually embedded in the brick but can sometimes be visible.
If your fireplace opening has a lintel that’s protruding slightly, make alterations for the lintel and include 1/8″ space to create sufficient space for clearance.
Here we can see the interior width of the fireplace in the back is 26″, and the inside height is 18″.
Similarly, you’ll gauge the width of your firebox from the opening (aka the face or outside measurement) and back (interior).
Cross-check the width at various heights to ensure that your firebox is symmetrical.
Theoretically, the width should be the same at all points on square fireboxes.
However, fireplaces with angled sidewalls will have different dimensions depending on where you take your measurements.
The depth is the extent from the face of your firebox to the back wall. Note the dimensions of your fireplace depth from the center of your firebox.
When deciding on the ideal fireplace insert for your house, use the smallest measurement. This way, your insert will adjust snugly without having to force it in.
Failing to do so could require some modifications to your existing fireplace opening. Do it right the first time!