Installing Durock correctly on a wood subfloor

[Gooserider]

LLigetfa - can you provide a technical reference that describes this application for the diamond lath, and how to use it to get such a gap?

The hearth pad thermal isolation technique I described was designed and certified by RSF engineers. In my case I purchased the assembled product from RSF. One could design/build their own but I doubt an inspector would sign off on it without an engineer's stamp. One could however, deploy the technique to build above minimum spec for their own peace of mind.

Yes and no, based on my own experience, and remembering back to when Elk was posting a lot as an inspector... There isn't a particular issue with home-built setups as long as you can show the inspector a manufacturer's technical data sheet or some other reference that says "This is a valid application" - at least to the effect that the material has a given R-value, and is appropriate for that application - (mineral wool has a high R-value, but doesn't work on a floor because it's compressible for instance)

If something you use doesn't have a technical backup, they might or might not buy it, and almost certainly won't give credit for the protection it might theoretically offer. Given that metal lath is a non-combustible, I doubt that they'd reject something using it, but I don't think they'd credit you with any R-value for it - and in most installs the challenge tends to be getting to the minimum required R-value (which is a very conservative number in the first place) without getting to thick - there is probably little safety benefit in making a hearth pad higher in R-value, though I do see some theoretical advantage in making it bigger in area, especially in front of loading doors.

Gooserider