Raising floors, raising firebox

[RGZeeBee]

Hi Fireplace Experts!

I’m hoping you have some suggestions for me regarding some remodeling I'm doing. I had a chimney sweep/repair person out to clean my fireplace and I asked him what he thought about what I was planning, but I’m not sure he had the background to really rely on his opinion, so I’m hoping an expert here can chime in. Here’s the situation:

Last month, my mother bought a bit of a fixer upper house built in 1948 that has a single chimney on what is “sort of an outside wall.” On the inside of the house, half of that chimney serves a living room wood burning fireplace that has a gas log in it from the 70’s (chimney sweep guy said it is a wood burning, and it has an ash clean out to basement in bottom of firebox). This living room is sunken from the surrounding floors by a luxurious 2.5”, so just enough to be annoying/trip on.

On the other side of the LR, there is a screened in porch area that shares the other half of the chimney with another fireplace with a separate clay flue. This porch firebox is also wood burning, according to chimney sweep.

The screened porch area is about 4 inches lower than the current sunken LR, and here in lies the problem: I am planning to insulate/HVAC/enclose this porch and make it part of the interior of the house, which will involve raising the LR floor AND the porch floor to be flat with the floors around it so my 75 year old mother doesn’t trip. So I’ll be raising the LR floor by 2.5” and the porch floor by 6.5”. This will involve raising the fireboxes of both fireplaces and that is where my questions come in.

I plan to trowel refractory cement to raise the LR firebox the 2.5” and I’m guessing that shouldn’t be a problem (?) But in the porch area, I need to raise that firebox a total of 6.5”, and it is already kind of short, something like 36” tall by 40” wide (I don’t have the dimensions with me today).

So here are my questions:

1) Regarding raising the porch fireplace: Can I (or someone else) break out the top of the firebox and build the firebox higher on the chimney so that I can keep the porch as a wood burning fireplace out there? I really like the option to burn wood, in case the power ever goes out for an extended period in winter in my area.

2) What is the minimum dimension of the porch firebox that I would need to keep it wood burning? I have looked at the ICC but I’m not seeing anything on minimum firebox dimensions or ratios for wood burning. (I’m a complete novice on fireplaces, so I might just be missing it).

3) If after raising the porch firebox, it is too short to have as a wood burning, or to be worthwhile at generating any heat for the home, I'm thinking I *could* convert the porch fireplace to gas and use one of those shorter, long contemporary-looking gas logs. Thoughts?

4) What should I use to raise the porch firebox up for the first 4 of the total 6.5 inches I need to raise it? Just standard ready mix concrete and finish the last 2.5 with refractory cement?

Thank you in advance for your ideas!

 

[bholler]

I plan to trowel refractory cement to raise the LR firebox the 2.5” and I’m guessing that shouldn’t be a problem (?)

Why would you do that firebrick are 2.5" thick just lay a new floor ontop of the old one.

1) Regarding raising the porch fireplace: Can I (or someone else) break out the top of the firebox and build the firebox higher on the chimney so that I can keep the porch as a wood burning fireplace out there? I really like the option to burn wood, in case the power ever goes out for an extended period in winter in my area.

Yes you can do that but it is not going to be cheap or easy it means moving up the lintel damper smoke shelf and smoke chamber. I would think you are looking at $2000 to $4000 roughly.

2) What is the minimum dimension of the porch firebox that I would need to keep it wood burning? I have looked at the ICC but I’m not seeing anything on minimum firebox dimensions or ratios for wood burning. (I’m a complete novice on fireplaces, so I might just be missing it).

There is no minimum really we would need exact dimensions and pics to give you and good info

3) If after raising the porch firebox, it is too short to have as a wood burning, or to be worthwhile at generating any heat for the home,

It likely will not be a worthwhile heater for the home now so I doubt changing the dimension will make it any better. It is pretty rare to have an open fireplace the contributes much if any real usable heat to the home.

4) What should I use to raise the porch firebox up for the first 4 of the total 6.5 inches I need to raise it? Just standard ready mix concrete and finish the last 2.5 with refractory cement?

Concrete underneath is fine but you dont finish with refractory cement you finish with firebrick. I suppose you could use refractory cement but then if there is a problem down the road you are redoing the whole floor instead of replacing a few brick

 

[RGZeeBee]

Why would you do that firebrick are 2.5" thick just lay a new floor ontop of the old one.


Yes you can do that but it is not going to be cheap or easy it means moving up the lintel damper smoke shelf and smoke chamber. I would think you are looking at $2000 to $4000 roughly.


There is no minimum really we would need exact dimensions and pics to give you and good info


It likely will not be a worthwhile heater for the home now so I doubt changing the dimension will make it any better. It is pretty rare to have an open fireplace the contributes much if any real usable heat to the home.


Concrete underneath is fine but you dont finish with refractory cement you finish with firebrick. I suppose you could use refractory cement but then if there is a problem down the road you are redoing the whole floor instead of replacing a few brick

Thanks, Bholler!

I was thinking of filling the 2.5" with refractory instead of using firebrick because I have to navigate around ash clean out and gas line, so thought would be easier to do with troweled product, also thought might be cheaper to do a big bucket of refractory over refractory + firebrick, but will price out and make sure, though I hear you on fixing potential issues down the road. Honestly, I'd be surprised if either fireplace gets used much at all, maybe 1 or 2x year, if that, so that may be someone else's road at that point

I will probably just go with low profile contemporary gas log on the patio side and save myself the headache and big $$$ to raise firebox, damper, lintel, etc.

Thanks again!

 

[bholler]

also thought might be cheaper to do a big bucket of refractory over refractory + firebrick

you will need more than one bucket of refractory to raise a whole floor 2.5" and fire brick are cheap compered to refractory.