I want to respond to your question. I don't know exactly where your numbers are coming from, but I think it'll help if I take you all the way through an example.
Let's do Oak Wood.
On this site: http://wiki.gekgasifier.com/w/page/6123766/Insulation%20Data
Oak is given a thermal conductivity of 0.17 W/mK
W (watts) is a rate of energy use.
m (meters) is a unit of length
K (Kelvin) is a unit of temperature
In my original post, I converted to units of thermal resistance, because that is how most people think. So we have:
1/(0.17 W/mK) = 5.88 mK/W
This still doesn't make much sense to people in the US because we are still stuck on IP units.
If you look at the website, there is a conversation table, and we can use it to help us convert to IP units. The IP units I choose are:
Btu in / (h ft2 oF)
Btu (British Thermal Unit) this is a measurement of energy, and is the amount of energy needed to raise one pound of water one degree Fahrenheit
in (inch) unit of length
h (hour) unit of time.
ft2 (square feet) unit of area
oF (degrees Fahrenheit) unit of Temperature
According to the conversation table, to convert from W/mK to Btu in / (h ft2 oF) multiply by 6.94
So, for IP units of thermal conductivity,
6.94*(0.17 W/mK) = 1.1798 (Btu in / (h ft2 oF))
For IP units of thermal resistance:
1/(1.1798 (Btu in / (h ft2 oF))) = 0.8476 (h ft2 oF) / (Btu in)
These units are very confusing but they are the actual units behind the R-value per inch I quoted above.