To SBR or PVA...........that is the question

[DIYedboy]

I remember reading somewhere that the pro's use SBR in preference to PVA, could you tell this poor old bodger what the difference is

 

[Richard C]

Are you referring to plastering or rendering? SBR (Styrene Butadiene Rubber) is a water resistant bonding/sealing agent. PVA (Polyvinyl Acetate) has many uses, undiluted as wood glue or diluted in general bonding & sealing applications. They have similar characteristics but the main difference is that SBR is not water soluble once dry whereas PVA remains water soluble. SBR will be more suitable in conditions where damp may be a problem in sand/cement renders & screeds, well suited for external render finishes or when tanking shower areas or swimming pools.

I only ever use PVA for plastering & it’s more than adequate for base & finishing plaster coats including render; but my rendering experience is limited to internal repairs & the odd scratch coat, some of the other guys do a lot more render work so they may confirm or otherwise. PVA is certainly less expensive.

 

[DIYedboy]

Thanks Richard, so it's SBR outside and PVA inside..............from reading some previous posts it seems that using PVA on the exterior is a definate no-no! and a hose pipe is the way forwards

On another note, I want to dustproof my garage floor (it has a DPM), in my last house I used unibond, but whenever it got wet, the floor went white, will SBR be more successful or is there something better, I'd rather not buy that expensive epoxy floor paint

 

[Richard C]

On another note, I want to dustproof my garage floor (it has a DPM), in my last house I used unibond, but whenever it got wet, the floor went white, will SBR be more successful or is there something better, I'd rather not buy that expensive epoxy floor paint

Unibond is basically a PVA so it is water soluble; on that basis, I suppose SBR would be more successful but I don't know for sure. I believe there are floor sealers available without going to the expense of epoxy so it might be worth a bit of investigation.

 

[DIYedboy]

Thanks Rich

 

[roy c]

Instead of sealing your concrete floor why don't you paint it with concrete paint? I have and always will use unibond in and outside. I have used SBR in my render mixes when specified but its an expensive game if you are doing it for yourself. It is usually specified if you are using a "tanking " or "dpc" system and getting chemicals from firms like"Sovereign" or the likes...

 

[DIYedboy]

Concrete floor paint tends to flake/wear off, but a seal soaks in and don't give you any further grief.

Coming back to the SBR or PVA argument, what about waterproof unibond which is EVA not PVA, does this still suffer from the PVA problems?

 

[Richard C]

Coming back to the SBR or PVA argument, what about waterproof unibond which is EVA not PVA, does this still suffer from the PVA problems?

No experience with it & didn’t know the answer so did a quick search & found this;

http://www.enigmatist.com/free/john49/pvafaq.htm

The fact sheet would seem to indicate it’s not much better than PVA but you have & read & decide for yourself!

 

[DIYedboy]

Thanks Rich, so that's it then, if you're outside and can't be bothered to hosepipe the wall, then it's a can of SBR everytime!

 

[roy c]

Yes!!! As everyone knows SBR is cheaper than water!!!