Is Old Crawl Space Butyl Tape Reusable?

Q: What happens to butyl tape when you replace the vapor barrier in a few years? Is old butyl tape reusable for the new vapor barrier? Would I have to apply a new strip of butyl tape under or over the currently installed rubberized butyl tape?

A: I don’t recommend using old butyl tape if you find yourself needing to replace the vapor barrier. Rubber tape is not like other tapes but it can still lose its effectiveness due to many reasons. Previously installed butyl tape and waterproof seam tape should be replaced when installing a new vapor barrier. 

What is Crawl Space Butyl Tape?

Butyl tapes are common in construction. They are used in roofing, HVAC, and crawl space encapsulation. Crawl space butyl tape is designed to do two things. 1. Create a seal between the foundation wall vapor retarder and the foundation wall. 2. Attach the vapor retarder to the foundation wall.

Crawl space butyl tape is a rubberized two-sided adhesive tape. Unlike waterproof seam tape which is one-sided and used to connect cut seams in vapor barrier. Rubberized tape can connect plastic to concrete or metal. Here are some other uses for butyl tape:

  • Connect glass to window frame
  • Roofing repair
  • Air sealing and connecting ductwork
  • Flashing repair on roofs and decks
  • Mobile home and RV repair
  • Minor temporary plumbing pipe repair
  • Car repair

How Good is Crawl Space Butyl Tape?

Rubber tape is better at sealing than attaching over the long term, in my opinion. Many contractors will install crawl space butyl tape as the primary anchor for the foundation wall vapor barrier. Unfortunately, over time, gravity can weaken the bond between the butyl tape, the foundation wall, and the plastic.

I recommend using a permanent fastener with rubberized tape. Installing a Christmas tree fastener or masonry nail or screw is a great way to permanently install vapor barriers on foundation walls. We offer a tool rental program to assist in installing vapor barrier and foundation wall insulation to the foundation wall.

When Should I Use Foundation Wall Butyl Tape?

If you are performing crawl space encapsulation by yourself, butyl tape is great. Installing vapor barrier to the foundation wall is cumbersome. Foundation wall rubber tape is like a helping hand. It can keep the plastic attached to the foundation wall to give you time to install the wall anchor or Christmas tree fastener.

Contact Crawl Space Ninja for Basement Waterproofing and Encapsulation

Please contact us to schedule your assessment to fix your crawl space, basement issue. 


Do you need help with mold removal, crawl space encapsulation, crawl space insulation, vapor barrier, waterproofing, foundation repair, basement waterproofing, or controlling humidity in your crawl space?

If you live in Georgia, Delaware, North Carolina, South Carolina, Tennessee, or Kentucky, Crawl Space Ninja can help!


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