Expert: James Ball - 7/19/2010

Question
QUESTION: We live in Bolivia, South America. We have a brick fireplace with slate rock on top of the chimney. Inside we have a iron liner with maybe a 4 inch pipe going up from it. We need to know some facts before tearing up the chimney.

ANSWER: Hello Beverly, not sure what the building code in in SA, but start with the building department, and a local mason, you could also check for a local chimney sweep, they should be able to help.
as far as why it might smoke, try opening a window and then using the fireplace see if that helps, if so then you have a negative pressure issue.
James

---------- FOLLOW-UP ----------

QUESTION: don't think we have a building code department!   We tried opening a window.  What I really need is the formula of if a building is x high and the chimney is x high and the mouth of the fireplace is x high and wide then how big does the flue need to be.  I've found here that I have to know the facts first before I can get someone to fix something.  Our roof is 6 meters high. I just went out and looked at the chimney and see that the cap on the chimney is the same height at the cap on the top of the peak of the house.  The roof is slanted and the chimney is in the middle of the slant.  I read on the site that the chimney needs to end at least 2 feet higher than tallest part of the house.  Is that right?  If we need to take off the roof to the chimney then it would be the time to cut out the metal flue that goes up.  I need the correct measurements before we start.

ANSWER: Welcome back Beverly, I understand you need a formula but that changes from town to town, country to country if I give you the code for my area it might not work for yours. there are so many different issues you might have with different materials, surrounding tree's, buildings, age of the chimney, how the fireplace was built, what size the fire box is, how the smoke chamber is built ....and so much more to just say ( a 2'x3' fireplace opening by 25' tall in a 7" x 11" flue that extends past the roof line by 5' might not work) I do not know
talk to your local masons, town hall, building department, chimney sweeps.
they deal with this all the time in your area and can give you a better idea how to approach this.
James


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QUESTION: I have had the soldering guy, an architect, and several masons look at it!  I was present when it was built.  We are in a third world country "without" codes for fireplaces.  The climate is like Miami Florida.  It is built with clay bricks with slate rock covering it.  It is 6 meters high.  The opening is 2 feet 7 inch wide and 1 1/2 ft high.  The flue is only an 8 inch pipe. There is space all around it at the bottom and about half way up there is concrete closing around the 8 inch pipe. People here just give opinions.  I haven't found someone advanced enough to know calculations.

Answer
Beverly I am sorry but I have no Idea what you need to make a fireplace in your area to work or what would be require, If you have no building department to check with then start with masons (they build chimneys in your area) I do not know what yours is constructed out of (I know you told me some materials but the do not sound correct)
"Inside we have a iron liner with maybe a 4 inch pipe going up from it"
A 4" pipe does not sound correct but then again I do not know what you have.
good luck
James