How do I measure a fireplace with an arched opening?
Measure width the same way — front and rear — but take height at two points: the maximum height at the top of the arch, and the height at the springline where the curve begins on each side, which is the lower number. Appliances fit the usable rectangle under the arch, so that shoulder height is what actually governs fit.
The two heights an arch needs
Record the maximum height from the floor up to the peak, or crown, of the arch. Then record the shoulder height — floor up to where the curve starts rising on each side. An insert or log set is a rectangular object, so it can only use the rectangle that fits beneath the arch. That means the shoulder height, and the width at that height, are the real numbers to size from, not the tempting full height at the peak.
Fit and finish on a curved opening
An insert's flat rectangular face won't follow the arch — there will be gaps at the top corners where the curve pulls away from the frame, and a surround panel or custom trim covers that. We flag it upfront so the finished look isn't a surprise when the fire's lit. Gas logs are more forgiving, since they sit on the firebox floor, but a tall log set still has to clear the shoulder height, not the peak, or it'll crowd the arch.
Get the arch measured on-site
Arched masonry openings are common in the older Asheville and Montford homes we work in, and each one is a little different. We measure the arch, the throat, and the flue, then plan the trim so the appliance sits clean under the curve. Take your peak and shoulder heights to start, and we'll confirm the rest. Request a free in-home assessment or call (828) 545-0525.
How we can help
Related questions
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