Barrier between first course and floor

[Furci]

In looking at several of the pictures I noticed that many people have what appears to be a cardboard barrier between their first course wall and floor. Is this indeed the case? If so, does it stay in?

Thanks again. I promise to get moving on some pictures now that we are progressing forward from lurker and information collector to builder and baker.

Sincerely,
A little naive and a little green in Syracuse

[vtsteve]

Re: Barrier between first course and floor

It's a corrugated cardboard spacer. It's used to leave a gap between the floor and the first course, so the floor won't crack the dome when it expands. You just leave it in place, and it burns out (eventually) during normal firing.

[brickie in oz]

Re: Barrier between first course and floor

It's a corrugated cardboard spacer. It's used to leave a gap between the floor and the first course, so the floor won't crack the dome when it expands. You just leave it in place, and it burns out (eventually) during normal firing.

Confused.....
Laying the bricks dry would have the same affect, sans the cardboard.

[vtsteve]

Re: Barrier between first course and floor

The vertical cardboard strip around the fitted floor keeps little bits of mortar and brick from getting into the gap as you build the walls. A couple of members have reported major dome cracks because the gap wasn't maintained (debris got in while they were building the walls, and it pushed the dome apart when the floor expanded). In use, the cardboard burns out and the gap fills with soft ash.

The spacer is needed only if you're building the dome around the floor (the floor bricks are cut to fit inside the dome). If you're laying the dome on the floor, just set first wall course dry on top of the floor (no mortar).

[Ken524]

Re: Barrier between first course and floor

[Les]

Re: Barrier between first course and floor

Ken, I'm not getting it. I didn't worry about the gap thinking there was plenty of space between all the brick in the hearth (as tight as I tried to place them). I have no issues by not using the "gap". Without going through the thread - did you install one?

[Ken524]

Re: Barrier between first course and floor

Hi Les,

I posted the "Mind the Gap" picture to be funny... I thought it was good timing .

I used the cardboard to maintain a gap between the floor and wall of my oven. After several years of pondering it, I now believe that planning for a gap probably isn't going to make much, if any, difference. The floor bricks all have small gaps in between them (even if you think they are tight) and the expansion we are talking about is pretty small (microns?). I would be surprised if the diameter of the floor changed enough to damage the oven wall.

Having the gap (which gets filled with ash) certainly doesn't hurt anything.

[Les]

Re: Barrier between first course and floor

Gotcha, I guess being safe does no harm.

Take care,

Les...

[Tscarborough]

Re: Barrier between first course and floor

Since the floor is generally cooler than the walls and the wall length is generally greater (well not generally, it is actually 3.14159 times greater) than the diameter of the oven, the expansion of the dome will more than allow for the expansion of the floor.

[Ken524]

Re: Barrier between first course and floor

Good answer! Give that man a piece of Pi.

[UtahBeehiver]

Re: Barrier between first course and floor

love those querky animations and pics.....btw, used you build as a reference guide for mine. Actually installed the cardboard spacer because your build. Whether it is a benefit or not I don't know but it did not hurt either. Thanks.