How tight do I pack the insulation into my riser? If I have a 6 inch thick piece of insulation and pack it into the riser so that it is compressed to 3 inches. Would this be adequate? Or do you not want any compression at all?

good question and hopefully some more knowledgable folks will chime in as i have the same question about my riser build.

You do not need to compress the insulation inside the riser.

Regards,
Terry