Expert: Bart Ogden - 10/26/2007

Question
QUESTION: Hello,
I have contracted a Paver company to install an outdoor paver patio, outdoor kitchen and fireplace.
I told him I wanted a complete masonry fireplace.
The exterior of the fireplace is made with Hanover Architectural products Wall pavers (2 13/16" thick variety). This wall unit is extremely sturdy.
The firebox is is being constructed with firebrick. The paver wall is built up about 18" on a 12" thick rebar footer (per my demand), the interior cavity filled with crusher run and a 3" thick concrete footer on top of that.
Two problems with the firebox construction (the workers are not brick masons):
1. The horizontal floor was constructed with about 3/16" mortar joints using Heat Stop Refractory Mortar. By the time I saw it the refractory mortar was cracking that afternoon. I read the Heat Stop bucket and it says to use Heat Stop II for high moisture applications.
The current status is they dug out the refractory mortar on the firebox floor and intend to use Heat Stop with Portland mixed in the fill in the mortar joints they dug out. I imagine a tile grouting like process.
Is this practice acceptable? Or, conversely, should they tear down the whole firebox and rebuild it properly (butter the bricks normally) to ensure sealing and bonding to the other bricks? I understand, from internet research, refractory cement is the code now.
2. They are using premixed mortar for the firebox vertical wall joints. However, I don't know if it is Type N mortar or not (N is reocmmneded by the BIA at bia.org). When building the vertical firebox walls, they laid multiple courses at a time. For example, they would build up the corners and then leave that to dry and fill in the middle sections the next day up to the height of the corner (5 courses high). I told them to tear it down and start over to ensure proper mortar bonding and prevent cracking. Because of my work, I wasn't here to verify they tore the vertical walls down and laid one course at a time.
The current status of the project: I told the contractor to not allow those guys to work on my fireplace any more and I wanted a bona-fide brick mason to build the firebox and chimney.
Can you provide some objective advice on the firebox construction practices and my decision to fire the subcontractor? My end goal is a fireplace that will last for a few decades.

ANSWER: Hi Tony,

The first problem is, as you mentioned, they're not fireplace builders!

They'll need to tear out the entire firebox and rebuild it using firebrick and non-water soluble refractory mortar.  The joints should be VERY thin and shouldn't need to be more than 1/8" to 3/16".

Type N is acceptable for the joint between the firebrick and the face brick.

It's should not be an issue to build the "leads" or starting courses, then fill the rest in later.

Sounds like the subcontractor did not have qualified personnel on the job.  I would have fired them as well!

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: Bart,

Thanks for the great advice. The contractor has a contract with the subcontractor which the subcontractor demands he gets to do the whole project from start to finish or he will tear up everything he has done. It appears he is too proud to have a real mason come and do the fireplace job. I feel like I am in a bind here. The contractor will go either way to protect his good name. I only want a quality project, done right the first time and at 3.5 weeks into it, I am hesitant to start over with a new crew.

A quick follow up: I checked the IRC and found this for masonry chimneys:
Masonry chimneys shall be supported on foundations of solid masonry or concrete at least 12 inches (305 mm) thick and at least 6 inches (152 mm) beyond each side of the exterior dimensions of the chimney. Footings shall be founded on natural, undisturbed earth below the frontline. In areas not subject to freezing, footings shall be located a minimum of 12 inches (305 mm) below finished grade.

They have a 12" below grade footing with rebar, then filled with crusher run, then about 2-3" of a cement footer where the firebrick rest on top of. Does this arrangement meet the requirements of the IRC or should they have another 12" of concrete footing?


Tony

Answer
Tony,

This should meet the requirements if the IRC.


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