Pva Versus Primers | Always Use A Primer When Tiling, And Not Pva - Tile Advice

[White Room]

Re: P.v.a. Versus Primers......

I've done site work for a contractor and never saw a bottle of primer although everything was dry lined, On a another job the walls was bucket gear (some tub gear state that no primer required) and that was on new plaster in a new private housing, Again no primer supplied. If your using cement addy on walls then it must be primed. I've used a mist coat of emulsion, artex sealer and sbr before and had no problems. The trouble with new plaster it's so absorbent and sucks the moisture from the adhesive giving it no time to cure properly, Thus giving in to failures at a later date.

 

[Viceroy]

Re: P.v.a. Versus Primers......

I,m totally confused with this !
I always used to pva diluted 1-4 plywood overlays (Never Had A Floor Fail)
then i was working with another tiler who used bal bond !
I Thought it was much better,so i started using that .
Talking to another tiler about it ,he told me the bal instructions on back of floor adhesive state you should only seal the sides and back face of ply ?
I now can't bring myself to tile directly onto a newly plyed floor without priming it !!!!!! so what do you fellas do on a newly plyed floor bond or no bond ?

Cheers

Viceroy

 

[DHTiling]

Re: P.v.a. Versus Primers......

BAL say you don't need to using there cement adhesives.......but other manufactures will say to prime...so always check on the bag.......

 

[Viceroy]

Re: P.v.a. Versus Primers......

Think youre right there !
Because Flexible profix (Dunlop) Say to use suitable primer !
Next job is with PCI
Tilefast 6 Rapidflex

The surface should be prepared to provide a rigid and secure base without deflection and suitable to support the
intended weight. Tongue and Groove/Chipboard must be over-boarded with exterior grade plywood which is at least
15mm thick and given time to find equilibrium with its surroundings. Plywood floors must be 18mm thick and all joints
must be supported. All must be screwed down every 300mm centers. The reverse face and edges of the boards must
be primed with Primer W to prevent the ingress of ambient moisture while the exposed face should be unprimed and
clean. Any existing wooden floor may also be over boarded with PCI Pecidur: minimum 10mm thick or PCI Polysilent:​

4mm or 7mm thick

Still not convinced about no primer !!!

Viceroy

 

[DHTiling]

Re: P.v.a. Versus Primers......

That also sez no primer...trust me i use BAL day in day out and it is fine......

Like i said if it sez prime then prime it if not then don't.........

 

[Viceroy]

Re: P.v.a. Versus Primers......

Cheers Dave !

 

[sWe]

Re: P.v.a. Versus Primers......

Many/most modern cement based adhesives are "primer free" to some extent. That means they don't require normally encountered surfaces, such as plasterboard or concrete, to be primed, BUT, there are almost always exceptions. The obvious ones are gypsum/anhydrite surfaces, (partly for the reaction risk, partly because they're very absorbant) and other surfaces which may react in some way when in contact with cement based materials.

Very absorbant or very non-absorbant surfaces may need to be primed.

Very absorbant surfaces can include certain light weight concretes and LECA, because otherwise they'll absorb too much moisture from the adhesive, thus preventing it from curing properly.

Very non-absorbant surfaces include already tiled surfaces, plastics, and metals, becuase the adhesive may not bond properly to them otherwise.

Always check the manufacturer instructions on wether or not an adhesive is suitable for the surface you intend to tile, and if your specific surface needs priming or not when using your chosen adhesive. It should say so on the bag. If it doesn't, don't risk it.

 

[dptiling]

Re: P.v.a. Versus Primers......

the pva my tile shop sells .has pva sealer and pimer on the front.
confused dot com or what.:confused_smile:

 

[Gazzatile]

Re: P.v.a. Versus Primers......

Dave very good article hopefuly this will mean fewer jobs failing

Gazza

 

[handyrabbit]

Re: P.v.a. Versus Primers......

brilliant! saves me asking the question why!!

glad i've moved house - pva'd a wall in my bathroom b4 tiling it!!

was there for 3 years after but i wonder mmmm???!!!

 

[David - Tradetiler]

Re: P.v.a. Versus Primers......

Just in case anyone missed it, because of this thread, we now stock SBR (at a really good price too) :yes:

[DLMURL="http://www.tradetiler.com/acatalog/siliconing_tiles.html#aSBR"]TradeTiler.Ltd Siliconing sealers/primers[/DLMURL]

 

[pt44]

Re: P.v.a. Versus Primers......

So, have I understood correctly - that SBR is a proper primer? not a PVA.

Also - from the small plastering knowledge and mortar knowledge that I have. I would normal pva seal a brick wall, with 1:4 pva mix. Let it dry, then redo it, with a 1:1 pva mix, and either plaster over it or render it with mortar, while the second mix is still tacky.

Can't beat PVA for plastering/rendering & patching in mortar or concrete (from my experience)

However, really interesting about why not to use it for Tiling.

Paul

 

[White Room]

Re: P.v.a. Versus Primers......

I don't use pva if I'm rendering a wall, I will dampen the brick wall with water then render but if has any variation of finishs on the wall then sbr or cement slurry.
PVA for plastering though

 

[GazTech]

Re: P.v.a. Versus Primers......

DESCRIPTION
A water-based dispersion of a styrene-butadiene copolymer with a
wide variety of uses in the construction industry, particularly as an
admixture and bonding agent for cement and concrete applications.
Once cured, the polymer is water and frost resistant.
January 2005
Cl/SfB
Yt4
APPLICATIONS & PERFORMANCE
BAL BOND SBR
USE & SERVICE CONDITIONS
BAL BOND SBR can be used as a slurry coat when mixed with hydraulic cement or gypsum plaster; as a multi-purpose admixture for
cement:sand mortars, concrete and gypsum plaster; as a brush applied primer, sealer or dustproofer.
STANDARDS
The high quality of this product is maintained through a stringent internal
quality assurance system conforming to BS EN ISO 9002 with regular
external quality assessments by independent authorities such as BSI.

 

[pt44]

Re: P.v.a. Versus Primers......

Waterproof PVA?

Ok, so normal PVA is no good, as it goes back to being glue if you add water, once it has dried. However, Waterproof PVA? What is it. Surely, the fact that it is waterproof means that it must have something in it - that stops it doing that. i.e. it must form a stable substance, that is not affected by water.

That then surely, is the same as SBR or a primer?

Or is it? Anyone?

Paul