# Forum Home Renovation Waterproofing  Waterproofing a Shower - can the Primer step ever be skipped?

## DaleBlack

Hi 
I have a brick cement rendered interior wall, the floor has recently been screeded. 
Any waterproofing product systems i have found all say to prime the substrates first, is there sometimes situations where it is not needed?
presumably because the adhesion between the chosen waterproof and the substrate is deemed to be decent enough without the aid of a primer?  
Rebuildr86 
In a older thread here  https://www.renovateforum.com/f247/w...render-124639/      

> I use gripset beta membrane, available at bunnings, and i apply it straight to cement render.
> For walls, davco powder mastic tile adhesive.
> Floors, ultraflex adhesive
> There are very few pure cement adhesives, no one uses them.

  Can I clarify when you say "I use gripset beta membrane, available at bunnings, and i apply it straight to cement render." Do you just use this product straight onto the screed ? no primer first?  http://www.gripsetbetta.com/under-tile-membrane/

----------


## rebuildr86

No need to prime unless its hard concrete. The first coat coes on and seeps in and fills the micro pinholes then the second and third do the actual waterproofing.
S9metime if its really pouros, it can be a good idea to thin the first coat a bit, and the reason for that is that when any kind of acrylic coating dries, it skins first, and if its a very thick coat it could skin on the surface and also on the backside on the substrate causing. A sandwich of non cured paint to remain sticky in the middle of that first coat. So if its very pouros, its a good idea to thin the first coat a bit. 
Now dont let that confuse you with floor levelling compounds, and their requirements for a primer on pouros substrates. Completely different kettle of fish there.

----------


## rebuildr86

On a screed it would be wise to thin it a bit, as screeds tend to be quite pouros. Unless of course you have used a waterproof screed product like the one by crommelin.

----------


## wspivak

If you're following the manufacturers instructions, then priming prior to using Gripset membranes is 100% required. 
The only thing that may vary is the type of primer used.  On porous substrates such as concrete, you can use general purpose primer (Gripset GP Primer).  On non-porous substrates you should use the Super Primer (aka Gripset OP Primer from the trade range). 
Lack of priming may lead to either pin-holing or de-lamination of the membrane. 
You can find the technical data sheets on their website at Waterproofing, Pavement Protection, Wooden Protection and Repair Solutions | Gripset Industries 
Hope that helps.

----------


## rebuildr86

Ok thanks for the add. Yes gripset is one of the best. But this is a different gripset isnt it? i was pretty sure theres "gripsetbetta" and gripset.
Anyway ive never only ever needed to prime old rough screed which was way too pourous for membrane.
When i come across something so pouros, its usually so rough and bumpy that it requires floor leveller before waterproofing. That means priming the old stuff before levelling (different kettle of fish) then just sticking the membrane (gripset betta) to that.

----------


## wspivak

Hi rebuildr86 - the products inside the bucket are identical.  Gripset Betta is the "retail" range of the Gripset "trade" brand. 
You can take a look at www.gripsetbetta.com for all their products/information. 
But from their site on the Under Tile Membrane: 
Priming is an important step in the application to optimise surface adhesion. Recommended primers for *UNDER TILE MEMBRANE*  Prep coat & Additive: Non tack primer coat for porous surfacesSuper Primer: For non porous and smooth surfacesDamp Stop: For surfaces subjected to rising damp or residual moisture 
Hope that helps.

----------

