Hi, complete beginner here in need of advice. I recently had a gas fireplace installed in the basement. When they pulled out the old one, there was this big hole underneath. I'd like to continue painting the raised hearth white/gray to match the top, but I need to fill that hole first. The hole goes down to 4" in places. Should I fill it with concrete, and if so, what kind? Since everything will be painted anyway, should I fill it up to 1" and then put some brick veneer on top, and then paint it? The guys installing the fireplace said to fill it with mortar but it seems like it's too big of a hole for that, though I'm obviously out of my element. Thank you in advance!
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