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Fireplace Design & Dimensions

Fireplace Design Literature

The Brick Industry Association (http://www.bia.org) has two excellent pamphlets about fireplace and chimney design and construction. Go to their web site and find the section on Technical Notes. Scroll down the left hand list of articles and click on the following titles:

#19 Residential Fireplace Design

#19A Residential Fireplaces, Details and Construction

Fireplace Sizing Table

All of the following dimensions are given in inches, except for Chimney Height. That value is given in feet. The firebox design is critical. Here is a photo of a new masonry firebox in my own home. The rear wall of the firebox rises vertically from the floor of the fireplace and then begins to slant towards the fireplace opening just at the top of the gas logs. The sidewalls of the firebox are vertical. Note that the firebox is not the same width front to back. It gets narrower towards the rear of the firebox!

The firebox depth does not include the thickness of the brick - or marble in my case - that faces your fireplace. This is very important! You can mix and match flue sizes with chimney heights. To properly size a flue, you must use a Nomograph. See the Brick Industry Association's Technical Note 19B - Residential Chimneys. It is always better to use the smaller flue size when you have two choices. When using the smaller flue size, you will be required to raise the height of the chimney. Taller chimneys draw better than short chimneys of the same flue size.

The smoke chamber height and design is very critical. You generally can't see this space as it is hidden above your fireplace damper. The height of the damper is very critical as well. The bottom of the damper should be a minimum of 8 inches above the top of the fireplace opening. If your damper is not at least 8 inches above this spot, you will have problems for sure! I urge you to read the pamphlets I have mentioned from the Brick Industry Association. They have excellent illustrations which will enable you to clearly see what I am trying to explain! The following table and its values are courtesy of the Brick Industry Association.

Firebox Dimensions and Chimney Heights

Fireplace Opening Width 24" 28" 32" 36" 40" 42" 48"
Fireplace Opening Height 24" 24" 29" 29" 29" 32" 32"
Firebox Depth 16" 16" 16" 16" 16" 16" 18"
Rear Firebox Width 11" 15" 19" 23" 27" 29" 33"
Rear Firebox Wall Vertical Height 14" 14" 14" 14" 14" 16" 16"
Nominal Flue Size 8x12 8x12 12x12 12x12 12x16 12x16 16x16
Minimum Chimney Height 15' 20' 18.5' 20.5' 13' 19.5' 16.5'


3 Responses to Fireplace Design & Dimensions

  1. Hi , i have a room (size 30ftx20 ft height 12ft ) i would loke to install chimney in the middle open all around , but i cant exit the hood direct from the roof . Can i open the hood from side ? what size of the exhaust is requested ? do you have material in brass?

  2. I'm putting a mantle on my fireplace , how many inches do I need from the fireplace to the mantle ? On the hight and width ? Please help I know legally u required so many inches I'm just not sure how much .

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