Plaster systems (Sto/Rockcote etc) - do they need painted?

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nofam

1094 posts

Uber Geek

#207710 10-Jan-2017 15:20

Hi All,

Am building soon using the Sto Poren system (plaster cladding over 50mm AAC panels on 140mm framing) and was wondering if someone who's built with this previously can confirm whether these systems need painting? The Sto website seems a bit vague, in that the final coat of render can be tinted, but it also mentions painting as well.

Would also be curious to know how others have found the performance of AAC - with the thicker framing and R4.0 batts this allows, I'm hoping for really good thermal and acoustic performance.

driller2000

935 posts

Ultimate Geek

ID Verified

#1700983 10-Jan-2017 15:47

Unless you like a grey plaster/mortar colour - which I would expect would discolour at different rates depending on location/shelter/sun exposure/weathering - I am thinking it would likely get painted - and therefore require maintenance as well?

PS: This is entirely speculation on my part as I have not used AAC - I do however have an EIFS clad / plaster finish home we had built in 2009 - so my observations above are based on this experience - and 8 years on I will likely be looking at getting our place painted within the next 2 years or so.

From a thermal/noise point of view - our place is excellent. Admittedly this is enhanced with the higher R ratings we achieved throughout + consideration of house/room orientation re sun and seasons + acoustic treatment to bedrooms (noiseline/silencer batts/solid core doors with all round seals etc) + double glazing which wasn't compulsory at the time.

PPS: AAC looks like a good option from a strength, durability and 80 year proven tech point of view. The key as always will be detailing - cavity / membranes / penetrations / flashings etc - compliance to manufacturer spec and most of all QA/QC and supervision re the installation phase ie. the best system on earth if installed by muppets will fail.

gkjb

128 posts

Master Geek

#1700987 10-Jan-2017 15:53

Our last house had a Sto finish. To the best of my recollection the final coat wasn't painted. We ended up repainting after 12 or so years as we were getting a soapy coloured runoff under a light hosing. Very easy to paint over with Resene X200.

nofam

1094 posts

Uber Geek

#1700997 10-Jan-2017 16:00

driller2000:

Unless you like a grey plaster/mortar colour - which I would expect would discolour at different rates depending on location/shelter/sun exposure/weathering - I am thinking it would likely get painted - and therefore require maintenance as well?

PS: This is entirely speculation on my part as I have not used AAC - I do however have an EIFS clad / plaster finish home we had built in 2009 - so my observations above are based on this experience - and 8 years on I will likely be looking at getting our place painted within the next 2 years or so.

From a thermal/noise point of view - our place is excellent. Admittedly this is enhanced with the higher R ratings we achieved throughout + consideration of house/room orientation re sun and seasons + acoustic treatment to bedrooms (noiseline/silencer batts/solid core doors with all round seals etc) + double glazing which wasn't compulsory at the time.

PPS: AAC looks like a good option from a strength, durability and 80 year proven tech point of view. The key as always will be detailing - cavity / membranes / penetrations / flashings etc - compliance to manufacturer spec and most of all QA/QC and supervision re the installation phase ie. the best system on earth if installed by muppets will fail.

Thanks Driller - yes, we looked at the EIFS system, but it wasn't much cheaper than AAC and EPS just isn't as durable - if it got hit with a cricket ball etc, you'd likely have to replace the whole panel, not just patch up the plaster. It's being applied by a licensed Sto applicator/LBP who our builder uses for all plaster houses he does, do I've no doubt that the quality will be bang-on. We're also having some sound-proofing done, mostly around the lounge - double-gib attached to gib rails to keep it off the studs, with green glue between, acoustic sealer around the edges, and no plugs/switches on that wall.

Fred99

13684 posts

Uber Geek

#1703004 13-Jan-2017 23:26

All these systems whether poly/plaster or autoclaved lightweight cement have similar clauses for repaint in 7/8 years.
They may call it something else, but the final coat is basically acrylic paint.

They probably tint the final coat of render so that you get good coverage / hiding power with the final coats, but that probably with darker/intense colours.

You'd probably get much more than 7/8 years, especially if it's a light colour, but they put this in to thoroughly cover their backsides.

Don't fret on it too much though - recoating is a very easy job (ie compared to repainting weatherboard etc).

BlinkyBill

1443 posts

Uber Geek
Inactive user

#1703025 14-Jan-2017 05:37

My house is 18 years old. 50% of the cladding is StoStucco, we have a 330 sq/m two story house in a very windy location. The Sto is not painted, it is tinted. Albeit it is a light, cream type of shade, the Sto is not faded or discoloured in any way.

From 18 years ago, my memory is Sto is not meant to be painted over, instead it is a render finish.

If I were you I would speak with the specialists - and the guys who did our house were Specialist Coatings, based in Wellington.

nofam

1094 posts

Uber Geek

#1708494 24-Jan-2017 10:01

Have finally had an answer on this from the Sto applicator; the plaster is coloured, but also painted with the same colour. Also, the standard Sto render is limited to colours that have a Light Reflective Value (LRV) of >30 (100 being white, 0 being black). You can go darker than 30, but it requires a different plaster/paint system, and adds considerable cost per m2 (approx 20% more).

Hope that helps anyone else with similar questions.