Your custom door is built to your exact opening — to the nearest 1/8 inch. Pick your fireplace type and we'll walk you through the right numbers.
Three tools and five quiet minutes. A second pair of hands helps but isn't required.
Stand the tape across the very top of the firebox opening, just under the lintel (the steel or stone bar that spans the top). Press it flat against both side walls. Round to the nearest 1/8 inch.
Tip: most masonry openings run 30–48" wide.
Now measure across the bottom of the opening at the hearth. Many masonry fireplaces are slightly wider at the bottom than the top — that's normal. Record both.
If top & bottom differ, we use the smaller for a clean fit.
From the hearth floor to the underside of the lintel, on the left wall of the opening. Keep the tape vertical and flat against the brick. Round to the nearest 1/8 inch.
Most masonry openings are 24–36" tall.
Repeat on the right side. If the lintel sags or the hearth slopes, this number won't match the left — we'll use the smaller of the two and the overlap covers the gap.
If left ≠ right, we use the smaller dimension.
A prefab (zero-clearance) firebox is a sealed steel box — its opening is even on all sides. Measure the inside width across the front of the metal opening. One number is enough.
Most ZC units run 30–42" wide. Measure inside the metal lip.
Now the inside height — top of the metal lip down to the inside of the floor. Same idea: the box is square so a single measurement is enough. Round to the nearest 1/8 inch.
Most ZC units run 22–30" tall. Plus your model number gets us the rest.
Fill in your measurements above and the safe size we'll use for your door appears here.
↓ Door spec belowWe add a 1.5" overlap on top and sides plus 1" at the bottom — that's the standard masonry overlap fit. Final dimensions go to our craftsman after the Expert Fit Review.
Hand-built and factory-built fireplaces both have surprises. Here's how we handle the most common ones.
Scan this QR code with your phone to place this fireplace door in your space using AR.
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