Best Practices for Installing a Crawl Space Vapor Barrier

[christinescoms]

Hello everyone,

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?

I’m also wondering if I need to seal the seams with tape or adhesive, and whether I should cover the entire ground area or just specific sections.

Additionally, is it necessary to extend the barrier up the walls, and if so, by how much?

Any tips on installation to ensure effectiveness would be greatly appreciated.

 

[rjenkinsgb]

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?

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!)

 

[aliarifat794]

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.

 

[ronsimpson]

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.

 

[Externet]

Not electronics. Move to 'Members lounge'

 

[ZipZapOuch]

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.

 

[auralee870]

Hello everyone,

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?

I’m also wondering if I need to seal the seams with tape or adhesive, and whether I should cover the entire ground area or just specific sections.

Additionally, is it necessary to extend the barrier up the walls, and if so, by how much? influencersgonewild

Any tips on installation to ensure effectiveness would be greatly appreciated.

When installing a vapor barrier in your crawl space, opting for a thicker barrier, such as 10-20 mil polyethylene, is generally recommended for durability and better moisture resistance, especially in areas prone to wear or damage. It’s important to seal the seams using specialized tape or adhesive to create a continuous barrier that effectively prevents moisture infiltration. Cover the entire ground area completely, as partial coverage can leave sections vulnerable to moisture. Extending the barrier up the walls by 6 to 12 inches and securing it with tape or fasteners is advisable to further reduce moisture entry. For an effective installation, ensure the surface is clean and free of debris, overlap the seams by several inches, and consider adding a dehumidifier for optimal moisture control.

 

[sagor1]

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.