Best Practices for Installing a Crawl Space Vapor Barrier

christinescoms said:

I’m in the process of installing a vapor barrier in my crawl space and have a few questions. Should I opt for a thicker barrier or is a thinner one sufficient?

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That's down to your local building regulations / codes. Also check if you need gastight or semipermeable.

Please respond to your existing questions rather than leaving people without a response.
(And stop duplicating question before anyone has even had chance to read them!)

Thinner barriers (6 to 10 mils) can be used but are more prone to damage. A thicker barrier, such as 12 to 20 mils, is more durable and resistant to tears and punctures.

I have plastic stapled to the bottom of the floor joists to keep the insulation dry. There is nothing on the ground.
In another house the plastic is on the ground and not on the house. The ground under the plastic is mud.
I do not know what is code. I cousin did both.

Not electronics. Move to 'Members lounge'

I would focus on local building codes because temperature range, humidity and construction norms (materials, rat walls, and drainage ) all affect condensation in the interior and wall-side of the vapor barrier. The condensation can lead to mold and mold spores as well as rot to any adjacent lumber. Talk to your local building department.

Thicker barrier is better. I've done one crawl space for my daughter many years ago with regular 6 mil plastic and it was ok. I sealed the seams with red barrier tape (Tuck tape?) used to seal vapour barriers in home insulation. What you do on the walls depends on what the walls are made of. In my case, it was concrete (blocks), and moisture goes through that, so I had to seal the walls as well. To be safe, I would do the walls regardless to keep all moisture out. You have to seal all "holes" including pipes, duct work, etc. with the barrier tape.