I've been pondering my sleeping mat system and was wondering if a Tyvex groundsheet would offer any additional insulation value - that is, some sort of R value in addition to the R value of my sleeping mat. Anyone know?

About diddly squit.

A search returns:

Does Tyvek have an R rating?

No, Tyvek house wrap itself does not have an R-value, which is a measure of thermal resistance or insulation. The purpose of a Tyvek house wrap is not to provide insulation, but to act as an air and moisture barrier. It blocks drafts and moistures, helping your insulation to do its job more effectively

Basically more use as either ground protection for your mat or as something to stand on while getting changed. Most "insulation" is really a means of separating top and bottom of the container while preventing the air (which is the actual insulator) from moving around, or at least not forming convection cells. This is why a Lilo type mat doesn't offer much insulation.

Ah well. Thanks very much for this Whitestone