Expert: Bart Ogden - 9/25/2007

Question
QUESTION: Had a guy build a brick fire pit in my back yard. He claimed he was a pro. We built one small fire in the pit approximately 10 days after the pit was finished. Now there are cracks everywhere in the mortar and even a couple of the bricks cracked.
The pit is approx. 27" diam. on the inside with a second wall on the outside with about 3" of space between them and a top cap of full size bricks that were cut pie shaped to form the circle. The brick is reg. house brick. The inside wall is stood on end and staggered 2 and 1/2 bricks high. The outside is bricks that have been cut in half and laid normal but forming a circle. This is all set on a pad of quickcrete about 2" diam. bigger than the outside wall of the pit. The mortar was regular house brick mortar.
What did he do wrong and can it be fixed or do I have to start over? He says we built the fire in it to soon and should have waited at least 3 weeks. Is this true?
I have purchased the regular brick and regular mortar for a second pit to be built by the same guy at my parents house but am waiting to find out if there is something better I can do.

ANSWER: Hi Teresa,

Firepits that wood is burned in should have firebrick in them and the firebrick should be mortared together with a non-water soluble fireclay compound.

Masonry dries very quickly, however, it takes 28 days for masonry to cure.

The bricks have cracked because they are not designed for this use.  They are not designed for high-heat that a woodburning fire emits.  The mortar has cracked because it is not a refractory-mortar, it is likely a type n or s mortar, that is not designed to withstand the heat of the fire.

Thanks for using AllExperts.Com and good luck with your project.

Sincerely,
A. Bart Ogden, President
Home Safe Hearth & Chimney, Inc.
Wichita, KS
Voice: 316-265-9828
Fax: 316-265-9890
www.homesafeks.com


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

QUESTION: Right or wrong? To build the 2nd pit he will need to first line the inside with firebrick, using the refractory mortar, then build the outside with regular brick.
Does he use the refractory mortar on the outside too?... and does the top cap need to be reg. brick or firebrick?... and does he use refractory mortar for it too?
Last what is refractory mortar and where do I get it? I have called several places (Home Depot,Ace True Value,Lowes) and everyone acts like I'm nutts. I even called a local stove and chimney place and they said all they had was something that comes in a tube like caulk and is for repairs.
Thank you.
Sincerely,
Teresa Lowry

Answer
Hi Teresa,

The 2nd pit, should be line with firebick laid with non-water-soluble refractory mortar.  Line it to the top of the pit.  This is what takes the heat.
Firebrick and non-water soluble refractory mortar should be available at any brickyard.

If, for some reason, you can't find it, you can email me and we can ship you some.


Thanks for using AllExperts.Com and good luck with your project.

Sincerely,
A. Bart Ogden, President
Home Safe Hearth & Chimney, Inc.
Wichita, KS
Voice: 316-265-9828
Fax: 316-265-9890
www.homesafeks.com