Fireplace Design & Dimensions

26 responses

  1. walid chehade
    December 18, 2012

    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?

    • Tim Carter
      January 3, 2013

      Walid, you should consider investing in a 15-Minute Consult with me. Look at my cart for that. Lot's to discuss. I just do short pithy answers here.

  2. Vika
    September 30, 2013

    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 .

  3. JoeTorbert
    May 14, 2014

    I have a customer that wants a 48 inch damper. They want the opening to be 60 inches tall. The fireplace opens outdoors to patio. Is it possible to do this ? All research says that it cant be but 38 inches tall.

    • Tim Carter
      May 14, 2014

      It may be possible. You need to order a 15-Minute Consult from me. Much to discuss.

  4. Sheldon Bacon
    October 13, 2014

    my house (and fireplace) was built in 1923, it has a 8X8 flue and the fireplace opening is 29 high x 42.5 wide and I set off my smoke detector every time I use the fire place. (18 deep and sides tapper to the back). I grew up around wood stoves and fireplaces but can not get this this to not smoke ( I use paper to start a draft, wood is now 2 years old, smokes using kiln dried oak boards) Based on the table from your website , do I need to reduce the opening to stop the smoking? and if so how.

    • Tim Carter
      October 15, 2014


      Read all my past columns about the shape and sizes of fireboxes, smoke shelves, flue sizes in relationship to fireplace size, etc. and then determine if your fireplace was doomed from day one.

    • Bryan
      March 15, 2015

      The mason's rule of thumb for your flue is it needs to be at least a 10% ratio of the opening of your fireplace: 29 x 42.5 = 1233 (10% is 123) Your flue is an 8 x 8 =64 than 123.
      You require a draft inducer or power vent fan that is designed to be installed at the top of your chimney & flue; and runs off electricity. Would be cheaper to order one yourself and hire an electrician to install and run control switch to fireplace room --may need another contractor or sweep to install on top; expect to spend at least $1500 for reasonable combined costs.?.
      I've been a custom FP professional for 15 years and am telling you this is about your only solution.

  5. Rus
    October 29, 2014


    I have to replace doors on the wood-burning fireplace.
    The opening in the wall is 25.5" x 36.5"

    What door format fits in this : small, medium or large (I'm a bit puzzled by the fact that actually any of the doors size specs available eg. from the LOWE's can fit that opening).

    Thank you for your time and consideration,

  6. Emory Kestner
    January 17, 2015

    I have a fireplace that is 34"H X 28"W with an 8" diameter flu liner. My chimney is 30' tall. This fireplace is in a room that is 16' X 16' with a door (my den) .. The liner is brand new ... The chimney has a cap on it that sits about 18' off of the top of the chimney...

    I started a fire the first time today in the fireplace after seventeen years... I have been refurbishing an old house that was built in 1750... The fireplace was the first thing that I had a contractor work on about 15years ago... The flu is a masonary liner that was poured inside of the chimney..

    The chimney smoked ??? Any suggestions ?? I opened two windows to allow for make up air.... I decreased the opening height by about four inches... The only thing other thing that I have not tried is to raise the height of the fire box by putting fire bricks in the bottom ...

    I have waited to have a fire in this den for 17 years hope you can help..

    God bless

    • Tim Carter
      January 18, 2015

      Yes I can help. Please READ all my columns about fireplace design and look at the tables about measurements with respect to all aspects of the shape and size of the fireplace. Pay attention to what I discuss about smoke shelves. Flue size is also important. They have to be perfectly sized. Fireplaces are very complex.

  7. Jim elchik
    January 29, 2015

    I'm building a masonary fireplace and I would like to have an opening of 48" wide x 48" tall. What would the remaining dimensions be? ( depth, rear wall width, rear wall vertical height, etc.....)

    • Tim Carter
      January 29, 2015

      Well, use the table I provided. You CAN'T have a square opening.... READ ALL of my columns about Fireplace Design, Fireplace Smoking, etc.

  8. T Schmidt
    March 23, 2015

    We are renovating a large floor to ceiling brick fireplace that overwhelms our small family room. Plan to remove the brick and reface with smooth finish/tile. We'd like to reduce the size of the fireplace opening (currently 25" tall x 40" wide to 20" tall. We do not want to put in gas insert. Fireplace is masonry w gas/gas logs.
    Is it possible to reduce the size of the fireplace opening?
    Thank you.

  9. D Lecky
    April 28, 2015

    We have a wood burning fireplace in a new home. When I try and light a fire, there is air blowing down the flu and the smoke goes back into the house. Someone has told me that this is called negative pressure. Once the fire is lit and gets the flu hot it will burn. I have tried opening a door when lighting the fire but it doesn't help. When the home was being constructed, the builder added a finished 3rd floor to our home and the top of the chimney is lower than the floor on the finished 3rd floor making finished area higher than the top of the chimney. My question is: Does the top of the chimney need to go higher than the fished area on the 3rd floor?

  10. Erik
    April 30, 2015

    I have a very large fireplace. The opening is presently 52" wide, and the thing doesn't draft well at all. I would like to rebrick that opening down to 42" wide so I can install off the shelf, rather than custom, doors. It's a 2 story house, and the chimney is about 30' tall. Thoughts?

    • Tim Carter
      April 30, 2015

      Yes. My thoughts are for you to go back up and read this column and look at the table that shows you all the relative sizes based on the opening. Just do what I say in the column and the smoke will go up the chimney.

  11. Thomas
    August 4, 2015

    Is it normal construction to have a built in Prefab Fireplace, with Metal Sides and Refractory Panels for the Bottom and Back?

  12. Diane Burkin
    September 3, 2015

    want to add depth to an existing fireplace to align it with bookcases on either side. The additional depth might be 8" or so. I could angle the new masonry clad walls back to the fireplace, but would this affect the draft?

  13. Austin
    November 25, 2015

    My girlfriend is set on getting a fireplace. She wants to put it in the middle of our livingroom which happens to be the middle wall of the double wide. Is it safe or even possible to put a fireplace in the middle of the house?
    About how much would it cost to get the fireplace put in and the vent out the roof?

  14. Margarett
    January 10, 2016

    I have a wood burning fireplace with 36"x30" opening and metal firebox inside of it,
    And I want to install lp gas insert that requires opening Niger then the existing opening
    What's the procedure to accomplish that?

  15. Rabee
    January 21, 2016

    I need all the size measurements to build a good fireplace ...Regards

  16. Frank
    February 28, 2016


    is it possible to consult with you? I have 2 fire places in a home my wife and i recently bought. One leaks water into the firebox fairly heavily when it rains. This unit down drafts heavily when cold and is an exterior chimney it fills the home with a burnt wood smell. This unit and the other unit both spill smoke when burning a fire. Looke at the damper and the bottom flat area of the damper is only 3 inches above both fireplace openings. Pleas advise what details would be needed prior to your consult and the fee associated with your time.

    Thank You

  17. Liz
    August 20, 2016

    I have a wall unit that is a veneer wood with a resin finish, but I would like to install an electric fireplace?
    The dimensions of the opining for the fireplace on my wall unit is 19"wide by 16 3/4 tall.
    Is this possible to do and How?

  18. Brennan
    September 23, 2016

    Hi Tim
    My office is in an old building and our landlords are allowing us to restore the fireplace. We've run a 6" round metal flue down the brick chimney cavity. We're now designing a metal firebox, but I'm unsure about what size opening we'll need to make sure it works well. Is there a fast answer for this question?

    Looking forward to hearing back.

  19. Kurt Kaufman
    December 31, 2016

    I have a fireplace with lousy draw, smoke rolls out the face rendering un usable.

    Fireplace Opening Width 30"
    Rear Firebox Width 29"
    Rear Firebox Wall Vertical Height 29"
    Nominal Flue Size, opening at top flange sheet metal. 13 1/2" X 4 1/4"
    Minimum Chimney Height 24"

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