Topic: Plaster over EPS

Plaster over EPS 

Hello...

I am trying to make my decision on the plaster type. The house is build from eco-block, so it is EPS.

There are two choices currently: Rockote or Sto. I have got in touch with Sto and they have provided a few plasterers and all of them do multiple systems. One of them will send me a quote for both systems.

From what I have heard, everybody recommends Sto for EPS because it is apparently stronger and less prone to cracking. It is not cement based.

Rockote s a bit cheaper (20 NZD/m2)...

Does anybody know of other alternatives or has experience with Rockote or Sto? Any good or bad experience is appreciated.

Thanks,
Dejan.

Re: Plaster over EPS 

Dejan - well done on picking ICF -they're good systems - it'll be easier than picking plaster.

And that's because the plastering industry is full of half truths obfuscation and sometimes just plain bulls..t

Let's start by looking a your question....

Not everyone recomends Sto - some will recommend one of the following.....rockcote, PSL, SpeciaIlised, Nu-age, wattle grano, MPT, putz tecnik, SAS, Europlast to name but a few...there are lots of choices

"Sto is apparently stronger"... If so ask them...say..."what is the ASTM you have used to test impact resistance, who undertook the test, what was the outcome and how does that compare to your competitors?" remember Dejan you are asking a reasonably thin product (plaster) to protect the poly. It's a hard thing to do

"Sto..cracking"- once again it's reasonable for you to ask for empirical testing results. Bear in mind also that for a crack to appear in ICFs the masonry must crack first then that must crack the poly then the plaster. I can tell u that a plasterer when presented with a fractured block wall will firstly affix poly sheet to act as a 'bond breaker'. ie the cracks in the substrate will be taken up in the flexible poly. What im saying is that ICF is ideal because cracks won't appear because they will be concealed by the poly. Don't buy a dog if you're going to bark yourself.

"Sto....is not cement based" - ring the bulls...t bell Dejan! . Read the spec don't listen to the rep. The spec (per their web ) says use SS105 stomat moral plaster system on eps block. SS105 begins with levelite then Sto armat then Colour. So take a quick look at the TDS for Sto levelite...binder: Portland cement. In english then..... The first coat of Sto plaster is a plaster made from sand, cement, poly beads, glue and a few other herbs and spices....the same stuff each of the 10 other fried chicken sellers mentioned earlier uses

Dejan it's getting late...going to bed...more later.. post to this topic so I know your reading it and I'll continue with more...

Righto!

Re: Plaster over EPS 

Whoknows...

Thanks for your writing... I would appreciate if you share your knowledge of the other systems... even in brief...
What would be your preferred system... the house is in Wellington... no freezing temperatures...

Regards,
Dejan.

Re: Plaster over EPS 

Hey Dejan,

let me know if i start to rant but.....

there are 3 aspects of quality...

impact test (self explaining) effectively a compression test - your drive is typically 17.5mpa

tensile test - if you held in your hand (like a sword) a 1m long stick of the product, how much load could you place on the end of the stick before it snapped? - to be fair no-one really does these tests for plaster

Adhesion - how well does the plaster stick to poly? This is the only test discussed in any NZ Standards - DBH AS E2 refers to ASTM E2134 as the test to use to see if the plaster will stick to poly. Long story but they get a 50 x 50mm sample put it in a machine which will pull it apart measuring the force required on Kilopascals BRANZ techies say 100 kpa is a good stick so
you need to say to any supplier - what was the outcome of your ASTM e2134 test?

So.. a few items to check then...

does the plasterer have an LBP ticket?
will the plaster stick with an adhesion better than 100kpa?
do you use alkali resistant reinforcement fiberglass mesh?
will you apply 3 coats of plaster - base coat, leveling coat and a final texture coat.?
Can you provide a 1sqm sample board (on sheet of board not part of the house) so we can agree what the final plaster should look like?
Will you apply a lime inhibiting primer
Will you apply a waterproofing acrylic elastomeric membrane in two coats? (aka really good paint)
Will you start and complete the job without interruption save poor weather
Are you ok with 50% progress payment after 3 coats plaster then 40% after first color coat of paint with 10% 14 days after completion
Can you supply references please.
Can you match any paint color i choose (over poly tho you should choose a light color)

If you get yes to all the above then you need to ask yourself - do i like this guy enough and trust him to do a good job - rely on your intuition Dejan and don't be scared to say no! - if you don't like the guy...if your radar is off then rely on your gut feeling and say no!

Finally price - its all over the place!..... most plasterers call themselves self employed but the reality is that the might as well work for the plaster companies (given the price of the plaster and their effective hourly rate)

Remember 60% of what goes on you wall will be sand.
You can pay as little or as much as you like.

For me i'd use any or all of the above plaster systems but the trick is to find the right person.

ps - don't worry about freezing/thawing. More wifestales! (no offence) Modern plasters have hydrophobic additives in their special herbs and spices and paint is an extra backup.

pps - repaint any plaster system often - eg every 5 years - its quick and cheap (i can recoat a 200sqm house in a long afternoon)

ppps - if i had to choose...any modern plaster system is ok - just make sure the paint has a lime lock primer and 2 coats Resene X200 - I'd work on a price of $75.00psqm + GST plus extra for height over 2.4m

righto!