internal plastering directly on EPS (ICF house)

[magnethead]

I was talking to an ICF manufacturer who had issues with 2 clients plastering directly onto EPS walls(shelling occurred).  In Europe with the much dryer air, this is apparently no problem. 

 

Here with the much higher humidity, he was explaining, that with a steel trowel, the outside layer of plaster Is sealed, and the moisture can not migrate back through the EPS layer , and that trapped layer of moisture makes the plaster much more likely to delaminate. maybe I picked up the theory wrong?

 

anyway, has anyone ever tried successfully to plaster directly onto EPS walls?

 

Thanks

[ADLIan]

Fire!! EPS will soften/melt, plaster will delaminate leaving eps exposed to add to the fire load. Mechanically fixed metal mesh as carrier may be an answer.

[nod]

As with external you will need a tight base coat and a fibre mesh 

The plaster will shell off without 

[magnethead]

Ah very good, the ICF blocks are grey and have a fire retardant (Neuro-toxin) added into them. 'Thermohouse' is the company. 

Great answer @nod  I'll put that back at him and see what he thinks.  for future repairs, maybe having boards would be easier

 

tape and jointing might be a cheaper way to go, but a few people have told me it's hard to pull off correctly.

[scottishjohn]

what you must remember is that in europe they nearly always spray the plaster on the walls --so it will be different stuff  i think 

not many here doing mechanical plastering yet

 

 

 

 

Edited January 13, 2020 by scottishjohn

[nod]

  On 13/01/2020 at 13:27, magnethead said:

Ah very good, the ICF blocks are grey and have a fire retardant (Neuro-toxin) added into them. 'Thermohouse' is the company. 

Great answer @nod  I'll put that back at him and see what he thinks.  for future repairs, maybe having boards would be easier

 

tape and jointing might be a cheaper way to go, but a few people have told me it's hard to pull off correctly.

Expand  

I contract both taping 

and Skimming 

The cost is the the same on houses Largely due to to taping materials being more expensive 
You only really gain with taping when the walls are above 3.5 metres 

[willbish]

  On 13/01/2020 at 12:41, magnethead said:

anyway, has anyone ever tried successfully to plaster directly onto EPS walls?

Expand  

Not yet but it is something I am considering.

I've had a quote, and had a test patch done for clay plaster directly onto the EPS. Primer and a backing coat with mesh pushed in then the clay.