Concrete Expansion Fireplace

[NickCat11]

Hello All,

I'm in the process of building my fireplace and I'm having second thoughts on how I handled the hearth area. See the picture attached. Instead of building it up with block I instead filled the hole with concrete and broken pieces of cinder block and then smoothed out the top so it's ready for fire brick. I figured it would be stronger this way. My concern now is the that the concrete may expand/contract in the hearth area and cause issues with the rest of the structure. The side and back walls are 16" wide and all the cores are filled completely with concrete. Do you think there will be an issue? If so, is there anyway to correct it?

 

[bud16415]

I think you will be ok. But I’m no expert.

Looks great. What are you going to burn in there?

Welcome to the forum.

 

[NickCat11]

Thanks Bud, I'm hoping it's going to be fine too. I'll be burning any type of wood I can get my hands on. Here's a better pic of the area of concern...

 

[BridgeMan]

I'm no expert either, but a concern I have is with the blocks and mortar joints absorbing rain water, which when heated by a hot fire, could create enough steam pressure to blow things apart.

Major efforts should be taken to keep water away from concrete blocks and mortar joints.