Hearth pad requirements for Vermont Castings stoves

[NYCaver]

So I was reading through the Vermont Castings Installation & Planning Guide (copyright 1987) and looks for guidance in building a hearth pad for my Vigilant.

The guide says that the minimum protection with standard legs is two sheets of 1/4" mineral board (or equivalent) covered by 24 gauge sheetmetal, left exposed. It goes on and seems to indicate that the only way more decorative materials may be added is with the use of a separate heat shield under the stove.

Can I really not add tile/brick/stone over top of the sheetmetal without a shield? What is the logic here? The guide seems to make no mention of raised hearth pads with airflow or any other options that seem to be considered good practice. I've never personally seen a hearth pad featuring bare steel as the final layer.

Without access to a heat shield I'm feeling pretty limited. Any advice?

 

[begreen]

If you want to do a tile hearth, no issue. What they require is that there be no gaps that embers can fall between. With a tiled hearth that is accomplished by the grout. With a brick hearth this is done with mortar or sand. The metal layer can go under the cement board in these cases. Use at least 1/2" cement board for a more rigid base and screw it down as recommended by the mfg..

 

[NYCaver]

Ok thanks for the reply. Is there any reason they might have called for the metal to be left exposed in the guide? Good to know the metal can go under the cement board, I was wondering about that.

 

[begreen]

The guide has several suggestions depending on the setup and materials used. You will note in the last paragraph the metal layer is not mentioned nor is it showing in figure 14.

The important thing is to note whether there is a bottom heatshield or not. If there is no bottom heatshield, I would definitely make the hearth with more insulation for more peace of mind. There is no harm in exceeding the minimums. You can do this by using two sheets of 1/2" cement board with sheet metal sandwiched in-between the layers. Screw this down per the board recommendation (usually every 8"), then tile on top.

 

[NYCaver]

As far as I can see, despite there being several suggested methods for hearth pad construction on that page there is only one method mentioned in the paragraph dealing with a stove with standard legs and no heat shield.

No metal layer is shown in figure 14 because that's an example of a setup with a bottom heat shield installed which does away with the need for metal in the pad.

Also note that the VC Techbook states "Installation of the Vermont Castings' Bottom Heat Shield allows a number of decorative hearth construction possibilities." In the preceding section concerning a stove with standard legs and no heat shield no decorative option is hinted at.

And nothing you mentioned explains why they would use the specific wording that the sheet metal should be left exposed. Surely, if adding a non-combustible over the metal was considered ok they would have worded it differently.

Sorry to be pedantic. I'm just used to the writers of technical manuals choosing their words very carefully. I'm sure a safe pad can be built with no heat shield and decorative materials beneath it, I'm just not convinced their instructions cover that possibility, and I'm wondering if they did that for a reason.