Rust coming through internal plaster on corners

[Bejinxed]

We have several rooms relatively recently replastered, well in the last few years, and the metal corner strips (whatever the proper name for them may be!) around all the window and door recesses seem to be rusting. The rusty colour is coming through the plaster and paint and in the worst areas the thin skim of plaster has come off entirely leaving rusty metal exposed.

Can anyone please suggest the best way and least expensive/disruptive way to deal with this and to help prevent it recurring?

 

[Richard C]

The corner beads should not be rusting. It sounds like you’ve got damp in there somewhere & the metal beading is rusting, expanding & blowing the skim off. You need to cure the damp before you can do anything about the beading which may have to be replaced if it's too far gone. Is the problem confined to external walls?

 

[Bejinxed]

It is mainly external walls, the exception being the recess around the bathroom door - though the bathroom would be more subject than most to condensation I suppose. We did have some problems with damp coming down the chimney, now fixed by fitting a cowl, but not anywhere near the plaster problems. The surveyor did go around the house with a damp meter though and said it was pretty good generally for a house of its age and construction (1899/stone blocks with brick corners).

 

[Richard C]

What sort of walls do you have, cavity or solid brick? Have you had the windows replaced?

 

[Bejinxed]

They are not cavity walls. They appear to vary between two and three and a half feet thick. The front is faced in rectangular stone blocks with brisk fancy bits on the corners and around the windows but the sides and back seem to more random lumps of stone with mortar holding it all together. On the inside, some of it is plaster direct on stone, the rest is plasterboard on battens. Yes we have had the windows and doors replaced with UPVC ones but the previous owners had already done that so in other words this is the second lot of replacement windows at least. They also had most of the replastering done. It sounds like we need to get someone out to check if we have a current damp problem or if it may be that it was damp at the time the plastering was done and only now coming to the surface?

 

[Bejinxed]

Sorry I meant brick fancy bits!

 

[roughcaster]

A couple of pics would be very helpful if possible Bej'.

 

[Richard C]

Photos would be good as RC said; is the problem around all the windows? The reason for my question about new windows is that incorrect/poor installation often leads to bridging the cavity across the window reveals but as you’ve solid walls that won’t apply. Poor installation can still lead to excessive wicking which will lead to excessive moisture in the wall.

Can you advise how the plastering was done, what preparation & what materials were used? It could be that unsuitable plaster materials have been used. Conventional Gypsum plaster on its own is unsuitable for replastering old, solid external brick walls which will always have a much higher moisture content than a modern cavity brick wall; unless replastering is done correctly using the right materials, you will eventually get problems.