Fireplace Opening Size

These are exterior measurements.

Fireplace opening size.

To provide adequate draft and safe venting of combustion products the chimney flue for a fireplace has to be adequate in size or cross sectional area. In general the flue can be 1 10th to 1 12th as large as the opening. A builder s opening or original fireplace is at the foot of almost every chimney flue and is of a pre determined size you get what you are given. I d hoped to have as big a fireplace as possible up to 60 wide.

Building codes typically require a minimum flue size expressed in terms of cross sectional area in relation to the area of the fire place opening. There are five key dimensions to measure the height and width of the opening the height and width of the back wall of the fireplace and the depth of the fireplace. Fireplace opening and flue size in creasing the chimney height in creases the amount of draft. I had another question regarding fireplace size.

This part of the fireplace is called the throat. The most common case is 1 10 of the fireplace opening area but with a minimum size specified. To properly size a flue you must use a nomograph. The opening width of this firebox is 42 3 4 at the face of the unit and the height is 35 1 4.

Do not confuse a small open fire with the builder s opening small open fires are often built within the builder s opening and excavation will reveal the larger recess. I checked out your specifications page and was hoping for some advice regarding fireplace size. The size of fireplace insert you require is related to the size of your existing masonry chimney. Since almost all fireplaces are different your exact opening size will determine the appropriate flashing or surround to accompany your insert.

Fireplace flue size specifications relation of fireplace size to flue opening dimensions table of required chimney flue size and flue dimensions for masonry fireplaces. This is a wonderful flue sizing tool. How high up should the damper be above the fireplace opening. The bottom of the damper should be a minimum of 8 inches above the top of the fireplace opening.

This article series provides information about masonry fireplaces. When a home is built with a masonry fireplace there is a huge range of possible sizes. The flashing or surround will cover the area where the insert meets the edge of the preexisting fireplace and cover any unsightly gaps.