Chimney Crown questions
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willy65000



Joined: 10 Sep 2010
Posts: 2
Location: Minnesota

PostPosted: Fri Sep 10, 2010 1:21 pm    Post subject: Chimney Crown questions Reply with quote

Hello, I hired a mason last fall to rebuild the top five feet of my soft brick chimney. Unfortunately instead of doing a cast in place crown he just smeared mortar on the top of the chimney and tightly around the clay flu liners. Now I have hairline cracks in the mortar and water dripping in my fire place when it rains so I'd like to remove the mortar crown and pour a cast in place one. I've looked at the Brick Industry Ass. technical notes and understand everything well with the exception of how I should support the clay flu liners that protrude through the crown. I'll be leaving a gap around each liner that will be filled with caulk. Is this sufficient support? Also, I'm assuming that because he did a quickie job on the crown that he probably didn't secure the top few flu liners using refractory cement and instead used regular masons mix. Will this be a problem or should I not worry about it.

Thank You,
Bill
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johnleeke
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Joined: 20 Aug 2004
Posts: 3009
Location: Portland, Maine, USA

PostPosted: Fri Sep 10, 2010 7:39 pm    Post subject: Reply with quote

I did a cast in place crown according to the Brick Industry Ass. technical notes. It came out just fine. When the form was in place, I put some old soft fiber board around the flue tile. This stuff was something like the 1950s "acoustic ceiling tile". Once the concrete was cured I dug out the fiber board and sealed the resulting gap with backer-rod and high-performance High-temp sealant made especially for this use. I don't recall the specific product.

The crown and seal was still in good condition when I sold the place 12 years later.

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willy65000



Joined: 10 Sep 2010
Posts: 2
Location: Minnesota

PostPosted: Sat Sep 11, 2010 7:20 pm    Post subject: Reply with quote

Thanks John. I'll be finishing my last course of brick tomorrow. Some of them came loose while removing the crown. How many days after setting that last course do I need to wait before I form and pour my crown. I'm worried about the weight and the compressive strength of the mortar and such. My plan was to pour next weekend.

Thanks,

Bill
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