What is the best way to Insulate the crawl space of an old home?
I have a 120 yr old home with a dirt crawl space that is completely dry, no Mold in the entire home, has new windows and new insulation in the attic. I have started the insulation in the floor joist from the crawlspace. I would like to know the correct way to insulate my crawl space regarding vapour barrier and what to do around vents and plumping pipes when installing.
There are a couple of ways to insulate the crawl space of an old home, either you can insulate the ground and keep the crawl space warm, or insulate between the joists as you mention and keep it cool. This page here will likely have the answers you are looking for -
How to insulate a dirt floor crawl space
Having a dry crawlspace is way better than having standing water, but part of the reason it is dry is that moisture in the soil is drying into the air, and that humidity will find its way into the main floor of your house. Do you have a hydrometer for testing the relative humidity? That would be a good thing to have.
Beyond what you learn on the above page, we can help you more with more information. Where are you located? And is there any mechanical equipment in your crawl space – water heater, plumbing, pipes, HRV, etc..?
And do you have a dehumidifier down there? You will likely still need one even after completing the insulation and vapour barrier, it is best to keep the humidity to below 50% RH. Let us know what else you have down there, because if you insulate between the joists then it's likely (or ‘inevitably’ given the way you spelled Vapour as that indicates you live in Canada) that it could freeze.
As for pipes, you can tape around them, and you can see how in this video on how to create a radon barrier in a slab on grade.