Expert: James Ball - 12/2/2009

Question
Hello, I need your advice on brick chimney repair.  

After a few days of heavy rain a month ago, chimney was leaking and carpet was wet. This is the first time we experienced leaking. I found chimney crown need to be replaced and mortal need to be repointed.  I got chimney repair information from Internet.  But there are still some unanswered questions that I would like to get your advice.

This one story brick ranch house was built in 1972 and we moved in 1997.  The size of wood burning chimney is 2’ by 6’ and 5’ high in the middle of roof and total high is 16’.  The big chimney has only one 12” by 12” tera cota flue liner in the center.

Chimney showed previous repair and one feet extension work.  The mortal between forth to sixth layer of bricks from the top is like sand and showing holes.  Top couple of layers shows black soil and dust between crown/mortal and brick so it came off easily.  When the chimney was extended one more foot, instead of a one feet tera cota liner, bricks were used.

After removing chimney crown and first layer of bricks from the top, I found loose bricks in the chamber.  First 1.5’ was filled with any bricks in a disorganized way and next 1.5’ was filled with original brick that the house and chimney was built in an organized way.  After 3’ there was a thick mortal coverage and a little difficult to dick further due to the depth and narrow space.  I just took out bricks from one side of tera cota liner and still need to do the other side.

My questions are:
First, is the chimney chamber need to be filled with loose brick creating heavy load to the structure?  If it is to support chimney crown and/or walls, then is any lighter frame (reinforcing rod like rebar or rebar with concrete) or brick frame (brick with mortal in every 12”—in this case put + shape brick and mortal at both side of flue liner) can be laid instead filling entire chamber with heavy bricks?

Second, can I plaster inside chimney wall with mortal mix (or concrete mix) to provide another protection to stop water?

Third, do I need to break current 3 feet bottom to find what’s underneath it and provide better leak protection?

Forth, can I place water stopping concrete barrier (or plastic barrier) with possible drain holes to outside chimney at current 3 feet bottom?

Fifth, do I need to work on weak chimney mortal in the attic also?

Last, any other advice you can provide?

Thank you for your help.

Steve from Roswell, Georgia. (Email: , Tel:  

Answer
Hello Steve, lets start with, you should get a good mason out to look at your chimney and get some prices on this type of repair it sounds like you need to have 5 or 7 coarse
(layers of brick) re placed from the top down, with a new crown, (you can water proof after if you want) then a good large cap ( Stainless steel or copper, that will cover the top  almost completely) and you should be fine. do not use plastic in the construction as it will hold more water that it keeps out. It sounded like they extended the chimney up with brick and not Teracota flue tile? if so re place with teracota when you re build. do not use cement on the inside of the chimney that should be smooth between the joints.
It also sounds like you are asking me if between the out side brick and the inside teracota can it be lose or must it be cemented? that would depend on what your local building department wants , ask them I call it "lose fill" and it should not touch the teracota flue at all the teracota should almost be free floating. also when they do the new crown there should be a minimum 1/2" gap left all the way around the treacota and the crown and filled with a good silicone after the cement is dry.
bottom line a chimney does a lot of work, so the joints need to be tight or re pointed, the bricks need to be solid or replaced, the crown must be done right or it will leak, and the flue needs a cap, water proofing will also help. talk to your building department and they will tell you what you need to do, if you need a permit. do it right and it will last many many years with out any trouble.
hope this helped
James