Mortar cracking on oven firebricks

I have some cracking on the mortar between the firebricks on my mattone barile. I havent laid the top 3 rows or the back or the chimmney yet, so its probably not too late to tear down the affected rows and start again. I placed them yesterday and the day before. The bricks had been soaked for at least 30 minutes, but some for 24+ hours, and I sprayed them with a mist every couple hours after I laid them. But, I live in the central valley of california and it was over 100 degrees on both days- hot, dry and sunny. Will these cracks, in the thickest areas of mortar at the “curviest” part of the oven, comprimise its integrity? Any insight would be great.

Hi Joy,

In my opinion, probably not a big problem. For the most part those cracks don’t seem to go up through an entire seam or all the way through a joint.

The barrel is also an arch, and so the weight and position of the bricks will serve to keep them in place. The two sides of the arch will be pressing against each other at the peak, which will also keep your bricks in place.

The mortar’s primary job is to maintain a seal between the heat and hot gases inside the oven, and the outer shell. Each seam is also providing a bed to keep the bricks under it at a proper angle.

I don’t believe the cracks are going to affect that. If you have a way to provide some shade for your remaining rows, you may want to use that just to give your mortar time to cure properly.

Agreed, I wouldn’t even give it a second thought…a few tiny cracks aren’t going to release more heat than the giant gaping chimney you purposely built into your oven. You’ll have a ceramic fiber blanket playing sheriff anyways, not to mention mortar and over weight compressing the blanket on top of the bricks! Looks good, don’t stress and make sure to enjoy the project!

Wow! Thanks so much for the reassurance. I was pretty concerned, even though I had considered the shape and weight of the bricks working to keep things together. I am REALLY grateful for this forum, and for both of your prompt and insightful replies.
Now, back to building! Almost there!

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