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.

Fireplace opening size.

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 part of the fireplace is called the throat. Since almost all fireplaces are different your exact opening size will determine the appropriate flashing or surround to accompany your insert. The size of fireplace insert you require is related to the size of your existing masonry chimney.

I had another question regarding fireplace size. The great room that the fireplace will be built in is 16 feet wide by 25 feet deep 400 sq ft with 10 ceilings. To properly size a flue you must use a nomograph. 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.

When a home is built with a masonry fireplace there is a huge range of possible sizes. I checked out your specifications page and was hoping for some advice regarding fireplace size. The flashing or surround will cover the area where the insert meets the edge of the preexisting fireplace and cover any unsightly gaps. 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.

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. This article series provides information about masonry fireplaces. These are exterior measurements. It s important to have a builder who knows how a fireplace works and makes sure the fireplace opening and the flue size are the right match to create excellent venting.

The most common case is 1 10 of the fireplace opening area but with a minimum size specified. The opening width of this firebox is 42 3 4 at the face of the unit and the height is 35 1 4. In general the flue can be 1 10th to 1 12th as large as the opening. This is a wonderful flue sizing tool.

The bottom of the damper should be a minimum of 8 inches above the top of the fireplace opening. How high up should the damper be above the fireplace opening. Interior measurements also need to be taken.