Exterior crack Design Styles, Chimneys and Finish Discuss Exterior crack in the Pizza Oven Design and Installation forums; All, I have some external crack issues I am trying to resolve, and I am looking for some ideas or ...

[JAG]

All,

I have some external crack issues I am trying to resolve, and I am looking for some ideas or thoughts on my planned direction forward.

First, the story of my crack. It is a hairline crack that only rears its ugly head during firing. It runs just off center of my outer arch, and propagates up the center of the chimney in the outer finish layer of stucco

The oven itself is blanket insulated, with a layer of vermicrete over that. The entrance arch where the crack is, is only insulated with vermicrete and the whole outer layer is stucco.

So, right now I am planning to remove all layers of verm and stucco down to firebrick on the tunnel and placing blanket insulation over the whole entrance and arch back to the dome. I was also planning on wrapping the chimney in blanket. Now comes the tricky part. For replacing the concrete/stucco finish I was going to pour a finish concrete sleeve to slide over the chimney, and then from there replace all other outer finish with formed and poured concrete panels over the tunnel. I can then use caulking to seal between concrete/stucco panels.

My whole thought process here is to isolate the finish layer from the oven structure itself, allowing the newly placed soft insulation and caulking to absorb the expansion of the tunnel.

This may be an extreme approach to eliminating the crack in the front of my oven, but I am rather anal and need to have a crack free outer surface, or at least not have the crack staring me in the face every time I use my oven.

Thoughts and alternative ideas are greatly welcome.


John

[DrakeRemoray]

I can understand you not wanting to stare at the crack...
Can you post some pictures?
Drake

[david s]

I've had success with fixing exterior cracks by covering the whole dome with fine chicken wire and rendering over the existing cracked layer. Your render mix should contain lime and cement. A normal cement render has very little elasticity, try a 4:1:1 sand, cement, lime mix.

[david s]

If the cracks are only hairline then an acrylic render that has good flexibility is suitable, but should only be applied after all moisture has been eliminated, which may take several decent cooking firings.