Oven Movement

[brickie in oz]

My oven floor is made from 300 x 300 mm tiles, when they were put down they were as tight as a ducks bum (watertight), now after lots of firing there is a 3mm gap between them all.
It just shows how much these ovens move around.

I have a feeling that the ash that falls into the gap each time it expands adds to the problem.

[Karangi Dude]

Al,
My hearth bricks have not moved at all they are as you say watertight.
The hearth is made of standard 230x115x75mm firebricks cut to shape to fit inside the walls.

[cobblerdave]

Gudday guys
Theres another point of difference between the two ovens other than size of hearth bricks. Doug your oven you mortared the first layer of bricks outside the hearth bricks containing the hearth bricks within. Al with your oven your oven structure is built on the hearth surface itself.
Its just a thought at this time...there are so many other difference that could come into play?
Al...is this really a problem though. Once the expantion has taken up, should it just stop? Surely the ash should act as a flexible expantion joint filler rather than forcing the hearth apart!

Regards Dave

[Neil2]

"containing the hearth bricks within"

Can't see this as a factor. If it wants to expand due to thermal expansion of the bricks, it will do so regardless of any thin mortar layer.