Hearth pad extension questions

[faultymechanics]

To be proper, the hearth floor in the fireplace and the hearth extension, should be one continuous cement base that is reinforced with metal (rebar or mesh).

Thread 'help with rebuilding hearth'

Jan 25, 2023

We recently purchased a 1925 home in Philadelphia, and we're having a wood-burning insert professionally installed in early March (it was the earliest they could get to us). However, I've needed to do some demolition of the old mantle (a super ugly 2x4, drywall, and mirror monstrosity) and hearth to get it ready for the installers. We have a 2" piece of slate countertop we're going to use for the hearth extension, but the more I dug into the work around the hearth--literally and metaphorically--the more questions I had.

The hearth extension doesn't seem to be connected to the hearth...

• A Stove in Philly
• Replies: 10
• Forum: The Hearth Room - Wood Stoves and Fireplaces

Post in thread 'Hearth extension is not supported nor attached?'

Jul 31, 2023

Cement board to close fireplace, 3/4" plywood for hearth extension, level frame around extension, will use that as a guide.



...22 bags of sacrete 6000psi 25kg/bag later:


We had 2 wheelbarrows, mixing in one while another being unloaded.

Learn from our mistakes: down't mix 2 bags at a time, it takes too much effort to do this. It's easier and faster to mix one bag in a wheelbarrow.
Used a steel angle with a level to scrape and level the surface.
For compacting, we used bosh drill hammer set into hammer only mode, and 2x4 flat attached to a bit. When compacting...

• TomasB

• 

Oh the actual base of the hearth is one giant cement pour, from 1930 so we dont know if there is rebar.

Im just adding more thermal protection to the existing hearth extension (but i need to demo the old tile first to fit in the new micore, durock and tile.

 

[begreen]

Is the current hearth extension deep enough to meet the new requirements? Is it all cement underneath (no wood form supporting it)?

 

[faultymechanics]

Is the current hearth extension deep enough?

Won't know until I demo the old one. Im guessing it will be about 1" higher than the current setup. I plan to use durock under the insert to level that out with the newly increased height of the extension.

Just saw your edit, current hearth extension has the form still under it and we're unsure due to the age if its structural(no clue if theres rebar inside) which is why I'm beefing up the extension.

 

[begreen]

The form should have been removed. It is not allowed to be under the fireplace by code.