Hearth Thickness

[toolmaster]

I have installed the chimney liner and am in the process of extending the hearth out 14 inches to allow for at least 16" in front of the stove. The current hearth is a concrete slab about 10" thick. It's not over earth; I can go into my basement and see the bottom of this slab. Can I put the stove (dutchwest catalytic) on top of the concrete hearth without the legs on it, or do I need to use the legs?

 

[nshif]

1ST off new code requires 18" in front of stove. This is somewhat debatable if the stove was spected for 16" but 2 more inches isnt that big of a deal and may make the inspector happy.
Does this slab have GOOD support under it? you are about to add a fair amount of weight to it.
Does this stove specify an R value for the hearh or just a non flamable surface?

 

[toolmaster]

There will definitely be 18" - although it was spec'd for 16. I can't tell how the slab is supported. The joists around it are doubled up. I'm assuming that there are some sort of support beams that are hidden by the second joists. I was planning on running an I-Beam under it to make sure it could support the 400lbs. My main concern is transfer too much heat?

1ST off new code requires 18" in front of stove. This is somewhat debatable if the stove was spected for 16" but 2 more inches isnt that big of a deal and may make the inspector happy.
Does this slab have GOOD support under it? you are about to add a fair amount of weight to it.
Does this stove specify an R value for the hearh or just a non flamable surface?

 

[webbie]

Does the stove even have an installations spec without the legs?
Let me take a look at the manual....
It does show an installation without legs, but cautions about heat traveling through the masonry to the wood framing beyond.

I doubt the entire stove is sitting exactly over the part without framing, and even if it is - the diagonal distance to wood framing cannot be very far.

I guess the first question is - do you need to use short or cut legs and/or is there any reason that you cannot use the legs? The legs provide for easier heat circulation around the stove, and also allow installation of the bottom heat shield. Even shorter legs and the installation of the bottom heat shield would vastly reduce the downward radiation.

Looking at the manual, it almost seems as if they are trying to be vague, but when you really read it, it makes it pretty clear:
1. Your hearth is considered a combustible hearth (because of wood framing in the front against the hearth (joists).
2. The stove cannot be installed on any combustible hearth without legs.

 

[nshif]

Looking at the picture your gonna want some more support. A 400Lb stove plus wood plus your weight and whatever else is up there aint gonna be good. The back looks well supported by the block wall if the slab extends over it but the front looks a bit weak

 

[toolmaster]

The stove would be sitting total over the concrete hearth – there would be about 4 inches in front of the stove on the thick slab. I need short legs – when I measured, it was with the old slate hearth to the top of the fireplace. Now that I have torn out and extended the hearth, the new slate tiles are a tad thicker and the stove won't fit with the 6” legs. Dutchwest sells 2” legs, but anyone I contact says it'll be 5 weeks before they arrive. I have considered either cutting down the existing legs, or placing a 1-2” thick piece of metal at each corner to raise it up a bit. Would a 1" gap be enough? Either way, I'll be supporting that slab with a beam as I don't know what is holding it up in the first place.



Is anyone familiar with a suspended slab hearth like this and how it may be supported?

Does the stove even have an installations spec without the legs?
Let me take a look at the manual....
It does show an installation without legs, but cautions about heat traveling through the masonry to the wood framing beyond.

I doubt the entire stove is sitting exactly over the part without framing, and even if it is - the diagonal distance to wood framing cannot be very far.

I guess the first question is - do you need to use short or cut legs and/or is there any reason that you cannot use the legs? The legs provide for easier heat circulation around the stove, and also allow installation of the bottom heat shield. Even shorter legs and the installation of the bottom heat shield would vastly reduce the downward radiation.

Looking at the manual, it almost seems as if they are trying to be vague, but when you really read it, it makes it pretty clear:
1. Your hearth is considered a combustible hearth (because of wood framing in the front against the hearth (joists).
2. The stove cannot be installed on any combustible hearth without legs.

 

[JimWalshin845]

If you place that insert directly on the hearth I bet you would be able to fry your morning breakfast on it. No way Jose' would I even think about it.

 

[webbie]

I would not worry much about the weight, especially if it is spread out on 4 legs and perhaps the rear legs would be back in the fireplace a bit.

It sounds like a lot, by myself and my dad sitting on your hearth would weight as much as your stove!

As long as your cut legs are as tall or taller than the short legs, you should be fine - don't use anything else except maybe a coin for a shim- use the bottom heat shield for certain. Again, I think you will not have to deal with the weight issue - should be fine.

 

[toolmaster]

Thanks - I appreciate the input. I'll cut a couple inches off the stock legs and post pics when it's all set. May be a while - haven't done the tilework yet. Hopefully...there'll still be some winter left when I'm done!

I would not worry much about the weight, especially if it is spread out on 4 legs and perhaps the rear legs would be back in the fireplace a bit.

It sounds like a lot, by myself and my dad sitting on your hearth would weight as much as your stove!

As long as your cut legs are as tall or taller than the short legs, you should be fine - don't use anything else except maybe a coin for a shim- use the bottom heat shield for certain. Again, I think you will not have to deal with the weight issue - should be fine.