ᐅ Plaster facade with external thermal insulation composite system (ETICS) using mineral wool – brown stains
Created on: 13 Feb 2023 21:27
W
wp.seeker
Hello everyone,
Our house was insulated and plastered between early and mid-November 2022.
The insulation is Rockwool Coverrock II, followed by a base coat, reinforcing mesh, top coat, and facade paint.
About two weeks later, brown spots appeared in various places, irregularly distributed on all sides of the facade. There are small spots and larger spots up to about 10cm (4 inches) in diameter, some pale, some intense brown-red. Over the course of 2–3 weeks, more spots showed up, but now no new ones seem to be appearing.
Has anyone had experience with this?
An online search suggested it could be moisture penetration dissolving the binding agents and fillers, or phenolic resin residues, resin pockets in the mineral wool boards themselves somehow coming through.
During the facade work, there were a few brief rain showers, so it’s possible the mineral wool got wet.
However, against the moisture penetration theory is that some spots appeared directly under the eaves, places that couldn’t have been exposed to rain, or on areas that were only installed after the rain. Overall, we had a very favorable weather window for that time of year.
The very irregular appearance could support the phenolic resin residue or resin pocket explanation. As far as we can tell, it’s not related to the board edges or possible fixing points.
Has anyone observed this phenomenon before and how was it resolved?
Thank you very much
Our house was insulated and plastered between early and mid-November 2022.
The insulation is Rockwool Coverrock II, followed by a base coat, reinforcing mesh, top coat, and facade paint.
About two weeks later, brown spots appeared in various places, irregularly distributed on all sides of the facade. There are small spots and larger spots up to about 10cm (4 inches) in diameter, some pale, some intense brown-red. Over the course of 2–3 weeks, more spots showed up, but now no new ones seem to be appearing.
Has anyone had experience with this?
An online search suggested it could be moisture penetration dissolving the binding agents and fillers, or phenolic resin residues, resin pockets in the mineral wool boards themselves somehow coming through.
During the facade work, there were a few brief rain showers, so it’s possible the mineral wool got wet.
However, against the moisture penetration theory is that some spots appeared directly under the eaves, places that couldn’t have been exposed to rain, or on areas that were only installed after the rain. Overall, we had a very favorable weather window for that time of year.
The very irregular appearance could support the phenolic resin residue or resin pocket explanation. As far as we can tell, it’s not related to the board edges or possible fixing points.
Has anyone observed this phenomenon before and how was it resolved?
Thank you very much
Apart from the brown stain on the lintel above the window, the other spots appear to be related to the filling of the holes for the scaffold anchors. Rainwater can also enter the ETICS (External Thermal Insulation Composite System) along the scaffold anchors, so moisture may have accumulated in those areas. The plugs for the anchor drill holes in the ETICS are usually professionally installed by the ETICS contractor. Sometimes, however, the scaffolder uses their own plugs during dismantling. Whether the materials are compatible may only become apparent later. This should be checked.
B
Benutzer 100114 Feb 2023 15:35wpic schrieb:
Apart from the brown stain on the window lintel, the other stains rather look like they are related to filling the holes for the scaffolding anchors in That would be so obvious that the plasterer should have noticed it. I would suggest opening the component at a stain that is not visible.
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