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Adhesive for Polyethelene Vapor Barrier

ajcates1's picture

I have recently installed a vapor barrier of 6 mil polyethylene sheeting on the dirt floor of my crawl space.  I have wrapped the sheeting up the concrete block walls about 12", and I would like to seal the top edge of it to the walls with some type of caulk or adhesive.  So far I have tried polyurethane construction adhesive, polyurethane caulk, silicone caulk, and acrylic caulk none of which will stick very well to the sheeting.  I'm thinking of maybe trying some kind of roofing cement.   What would be a good caulk or adhesive to use that will stick to polyethylene sheeting?

(post #112450, reply #1 of 15)

Acoustical sealant. Wasn't designed for vapour barriers but works well.

(post #112450, reply #2 of 15)

What is it normally used for and where can I buy it?  Does it come in a tube like caulk?

(post #112450, reply #4 of 15)

Used for sealing cracks/smallgaps where sound may travel through separating walls, etc. Should be available at any larger hardware store. Comes in 2 size tubes. It's black, really gooey and stringy plus it never really hardens so it maintains its seal for a long time.

(post #112450, reply #12 of 15)

Re: "Acoustical sealant"

That is what I see the majority of contractors seem to be using when they can't use the tape.

(post #112450, reply #13 of 15)

Up here in Canada, acoustical  has been used since about 1980-1 as a sealant for AVB's in super insulated housing. Some one mentioned earlier how it sticks to everything. YES!!!

I used to be an inspector for Canada's R2000 program, the high efficiency home national program here. One night I had to do the quality control air leakage test for a contractor friend as the drywallers were coming first thing in the AM. We were sealing and testing until 10 PM. We were quite frantic and using all kinds of tape and acoustical to make sure he met the test limits.

After we were finished, I went home and directly to bed, no shower. The next morning I woke up and when I went to lift my head off the pillow, I felt a little tug on my hair. Some of the acoustical followed me right into bed in my hair!! Damn stuff.

(post #112450, reply #14 of 15)

It is tenacious stuff. On commercial sites it is spread about like holy water during the blessing of the lepers. Before the bottom plate or track goes down it gets two beads. Drywall is kept about 3/16 high off the slab and after that is caulked with the same stuff.

My main complaint comes when they demand my steel boxes be smeared with it, supposed to increase noise rating, and then, once the drywall is up they caulk around my boxes.

Did I mention that it takes a good time before this stuff cures, it never, as far as I can tell, hardens. Which means that the skinned over beads, as you well know, are still subject to being smeared on wires, tools, fish tapes, hands and arms while we pull in the wire and terminate.

(post #112450, reply #3 of 15)

What experienced said.

Comes in caulking tube, grey or black. Any lumber yard/building center should have them.

(post #112450, reply #5 of 15)

You may have to wipe off the surface you are trying to glue--the poly that is--they powder it to unfold nicely--talc type

Other wise I have used my Hilti gun with regular foam in it and smoothed it over with my hand running along the poly.

worked like a charm and no caulk gun--more expensive no dougt but it got me out with minimal pain.

welcome aboard--glad to have you.


" I reject your reality and substitute my own"
Adam Savage---Mythbusters

Mike "Even a blind squirrel finds a nut once in a while" Mitremike c. 1990 " I reject your reality and substitute my own" Adam Savage---Mythbusters

(post #112450, reply #6 of 15)

For fast,quick hold, you can use spray adhesive. Spray the poly and spray the block.

this will give the more "permanant" adhesive time to set up.


(post #112450, reply #7 of 15)

used cheapest drywall adhesive for this 38 years ago and it is still holding.

(post #112450, reply #8 of 15)

If you can't find acoustical caulk, (or it's too expensive--I haven't even looked) butyl caulk may work (if you can find it). It also never hardens and is pretty sticky.

(post #112450, reply #9 of 15)

I just did the same thing, used polyurethane caulk with no problem. As others have suggested there might be other factors causing it to not stick.

(post #112450, reply #10 of 15)

Acoustic sealant is about the only thing that sticks to poly VB reliably long term.  It does so by NEVER DRYING- it never sets up hard or rubbery like a normal caulking material.  Rather it stays as a sticky goo more or less permanently.  But as long as it's behind the layer of polyethylene, it's doing its job.   It sticks to everything more or less- drywall, wood, poly, fingers, hair etc., so keep it off ya!

Acoustic sealant is just like peel & stick ice and water shield for the eaves- you know it works great because it's such a PITA to work with and it's not cheap, but people still buy gobs of the stuff.

Bringing up an old thread.  (post #112450, reply #15 of 15)

Bringing up an old thread.  I am about to do the same as the original poster and wanted to find out if the water based acoustic sealant that is sold at the big box stores today will still be good to use with polyethylene sheeting. I would send a message direct to moltenmetal with this question, but I am new to this forum and cannot send messages.

I would also like to know what it takes for me to be able to send messages.

(post #112450, reply #11 of 15)

Surprised the poly caulk did not work.

Has always stuck well to poly in my experience.  I use PL Roofing and Flashing, which is thinner and gooier than the 'door and window' stuff.