DPM tape behaving oddly.

[MikeSharp01]

Just wandered out onto site and spotted a problem with the DPM seams. They each have two tapes making the seal one double sided a bit back from the edge and the other single sided along the edge. The single sided is showing signs of lifting (see pic) in patches. Both tapes were rolled / rollered on as per the Visqueen video (all tapes are Visqueen). I wonder how important the single sided run is, is it just protecting the double sided inner row? Do I need to  take it up and do it again?

 

[Cpd]

Unsure of the correct proceeder but the stuff I used was the wide black  double sided sticky stuff that is semi flexible and insanely sticky ! Once it goes down it’s down....... seems very strange that a product like this is lifting, it looks like it’s just not sticking to the plastic. If both tapes are failing and there is ANY chance of water getting in from below or above I would be having it up and using a different product. 

[Russell griffiths]

Once there’s 20 tonne of concrete on top I’m pretty sure it won’t be a problem 

never used to tape them, just a good lap. 

[MikeSharp01]

11 minutes ago, Cpd said:

Unsure of the correct proceeder but the stuff I used was the wide black  double sided sticky stuff that is semi flexible and insanely sticky

Yes I have that, well the visqueen equivalent,  between the two sheets all along the joins and the tape that is failing just along the flapping edge as it were. Here is a quick sketch. 

[MikeSharp01]

5 minutes ago, Russell griffiths said:

Once there’s 20 tonne of concrete on top I’m pretty sure it won’t be a problem 

never used to tape them, just a good lap.

Yes - so I understand,  the weight of the concrete will crush the overlap, in my case further pressing down on the double sided tape in between the sheets as well. Hope the BCO see's it your way.

 

[Russell griffiths]

If it’s a reinforced slab 

stick a row of chairs along the join to pin it down 

[Declan52]

It's more than likely the sun making the dpm expand and causing the tape to come loose.

As above once the concrete is on top it won't go anywhere.

[MikeSharp01]

I have asked the BCO what thy want me to do. 

 

Here is a better sketch:

 

 

 

of what I am doing - just like the Visqueen Video

Edited July 26, 2018 by MikeSharp01

[PeterW]

I wouldn’t even bother - the double sided has got it anyway and the lap is more than enough. 

 

Make sure you pour the concrete on the upper piece first and it will hold the lap down

[Cpd]

Also agree after seeing the pic. I only use  the double sided and a generous overlap.