Rusting corner reinforcing mesh on internal walls

steamdave

The steel corner reinforcing mesh in several rooms is rusting and staining the wall paint. The "correct" way to fix it is probably to cut out the old mesh and install new and replaster. Messy and expensive!

Are there any suggestions on hiding the rust marks that don't involve plaster surgery? I have tried oil based paint under the water based emulsion, but that only delays the stains coming through a short while.

Dave

10-10-20

(posted this in the previous thread, posting here too)

Steel corner beads are supposed to be galvanised so that they resist rusting, but this protection can only last so long before it breaks through and stains the wall. The fact that the beads are made from metal means that they are the first object in the room to release their thermal energy, therefor becoming colder quicker than the surrounding air. The problem then is that if the relative humidity in the house is high then the dew-point (the temperature that water condenses on a surface) will also be high, so the moisture will gather on and around the coldest surface in the room - in this case it's the beads.

The overall solution is to ventilate more, isolate and eliminate internal sources of humidity (run bathroom fans more, use lids on pots, dry clothes outside or in a dryer, etc.), increase the ambient temperature and dehumidify where appropriate. Beyond that you could consider increased insulation to keep the house warmer, but be aware that by adding heat you also increase the ability of the air to hold more moisture, so when it cools down, it all has to condense somewhere!

To fix the rusting beads, the best option is probably to replace them as their protection has gone so they are susceptible to further corrosion if the conditions dis-improve again.

Mr321

Impossible to hide rust n matter how much you cover it. Could be poorly galvanised or have been cut leading to it starting to rust but probably a mix of that and what @10-10-20 has said.

If your going down the replacing route replace them with the pvc corner bead.