Tape for Underlayments

[Ernesto]

Had a discussion about this last night with someone and wanted more input.

I rannout of packing tape on my laminate job yesterday by about ten feet so I whipped out some silicone to seal the six mil together with which is always overlapped at least six inches.
The discussion evolved into not whether or not the silicone would seal it but he says 2 mil packing tape is a weak spot since your supposed to use heavier tape and 2 mil is not like.a.six mil.
I say it is all about the bond, much like the flap on rolls of 2&1 underlayment.
I've been using packing tape for five years with six mil no problems here.
What's your take?

 

[Nick]

packing tape is all i use . Fast with the gun . waterproof .
Duct tape is only a retarder .
Never had a problem . First time i used it was afraid it might make noise under the lam .

 

[Ernesto]

Nick, isin't the red duck tape waterproof? Talk about expensive. Kinda like that foil tape for the foil backed rubberized underlayment, wowzers!

I know Duck brand makes a 3.1 mil packaging tape. It's only like 12 bucks for six rolls. But whats the use if packaging tape is waterproof, if its water proof then it has a lower perm rating than six mill dont it?

 

[Nick]

Never seen the red in these parts E.
Now they have it in all different colors ,and designs .

If it's not broke , Don't fix it .
Regular duct tape here is like $6.00 a roll, and it's a lot thinner then it use to be . The only thing i use it for is pad seems .

Never couldn't understand why installers insist on stapling the seems , and compressing the pad .

 

[FloorMaven]

I don't have a problem with packing tape...it's probably better than no tape as it was spec'd years ago.

If I suspect a border line subfloor I will spec a better tape.

 

[Ernesto]

I don't have a problem with packing tape...it's probably better than no tape as it was spec'd years ago.

If I suspect a border line subfloor I will spec a better tape.

What's better than waterproof? Does thicker mean its better if both are are.waterproof?

 

[FloorMaven]

What's better than waterproof? Does thicker mean its better if both are are.waterproof?

The molecular structure of moisture vapor is very different than that of water. Ie something can be waterproof but still allow some degree of moisture vapor to pass. Packing tape is usually polypropylene or polyester, both have similar perm ratings as the same thickness of virgin polyethylene- the most common vapor retarder used under floating floors. Aluminum has a 0 perm rating...

 

[Ernesto]

That's interesting. So it would be worse to have moisture vapor than actual water under your vapor retarder?
I know the foil is best but if the MVE will actually condense under foil.will it help at all? Imagine a worst case scenerio where vapor turns to water and how many slabs are actually tested prior to an installation. I know the box stores don't do it at all or they do test it is a CME.

 

[FloorMaven]

You're probably looking at a failure long bbefore condensation.

From DuPont:

WHAT IS VAPOR PERMEABILITY?
Vapor permeability (commonly referred to as breathability) is a material’s ability to allow water “vapor” to pass. This is often confused with the concept of holding out bulk water. So what’s the difference? Bulk water is moisture in liquid form; water vapor is a gas. Also, the amount of moisture that moves and the method of movement are significantly different. A single drop of water consists of thousands of molecules. In general this can be compared to a crowd of people who do everything together. This is the way they like to travel. Now just imagine this crowd of people trying to go through a door all at the same time. They won’t fit so no one gets through. But just suppose everyone in the crowd spreads out, and in an orderly fashion and one-by-one, they attempted to exit. Some of them would get out.

 

[Nick]

Makes sense .

 

[Ernesto]

You know whats funny about the permeance of materials? The test is done by the dessicant method; E 96/E 96M – 05
Standard Test Methods for
Water Vapor Transmission of Materials1

Foil is rated zero, yes, but depends on its thickness. Thinner films of foil do have a lower perm rating. But I guess you could call a thick enough foil a vapor barrier instead of a vapor retarder. Thus is the reason they call 6 mil poly a retarder and thicker mil poly a barrier.

I just R&R'd 700' sq of laminate with an attached cushion the DIY'r installed with no six mil or anything under it. Installed it in middle May, didn't start buckling until the first part of July when the humidity and monsons came. Found a few really dark damp spots under the lam in a couple places, in that area there was some minute specks of black mold in the locking mechanisms which were disposed of. Kinda weird it lasted as long as it did.

 

[Ken]

Watch your tongue ernie, i test slabs, lmao! Man, someone at a box store must have pissed in your corn flakes, haha.

 

[Ernesto]

Which testing do you do? Plastic sheet test? Lol

 

[Nick]

 

[Ken]

ive got the GE aquaint for simple scans and i like the wagner rh probes, thats probably more than most installers do which around here is nothing.

 

[Ernesto]

Your right, when I do inspections there's no moisture test and if there was it is a CME over paint residue. For laminate and floating wood.

 

[Ernesto]

ive got the GE aquaint for simple scans and i like the wagner rh probes, thats probably more than most installers do which around here is nothing.

I can't find that meter by GE. Is it a survey master?

 

[Ken]

http://www.inspectortools.com/ProductDetails.asp?ProductCode=PR5760&gclid=COyWr7bO2LgCFYak4AodKSQAIA