Stain in plaster

[Dirtybill]

Went to a job yesterday where the guy has a weird yellow looking stain on one wall in his livingroom, he is in a top floor, three story block of flats and the wall is on the gable side. I went into his loft space and had a good look aroud the area however there was no evidence of a roof leak and certainly nothing penetrating the stonework anyway he wanted the plaster removed and re done in that area so i set up and began to remove the heavy painted lining paper over the top, whilst i was doing this the wall sounded bossed and on further digging it turns out there is a sheet of gyproc in that area (brown side out) which has been completely plastered over and finished. (obviously been work done there in past, before current owner)

I took the lining paper of and the finish coat and the backing coat had no evidence of water staining or dampness, so im wondering what the staining could be it's also on the cornice above which i aint touching!

Any ideas, and do you think it would be advisable just finish over the plaster thats already in situ?

 

[henry]

is it our old friend nicotine

 

[Dirtybill]

Its that kinda colour however it's just one area and the it's localised over a previous repair, the original walls are lime plaster and the repaired bit is and i asssume is bonding on plasterboard with multi on top, the stain appeared after the current owner had his living room painted and the stain has neither got bigger or darker.

 

[bubbles65]

could be the different backgrounds are different temperatures and therefore condensation on the walls will make the patch appear a different colour:RpS_thumbup:

 

[Dirtybill]

Yep possibly, but that doesn't explain the same stain on the cornice above.

Personally i think it may have been a freak water pen through roof or gable and it's just a one off as there is no real evidence in loft persistant water pen hence the size of stain, if you get me?

 

[irish_spread]

Its that kinda colour however it's just one area and the it's localised over a previous repair, the original walls are lime plaster and the repaired bit is and i asssume is bonding on plasterboard with multi on top, the stain appeared after the current owner had his living room painted and the stain has neither got bigger or darker.

is it just above his ashtray ?

 

[spunky]

To be on the safe side could he go over it with artex sealer?

 

[Dirtybill]

Just finished it so will suck it and see in regards to the plaster, if the stain comes back then it's obviously the backing.

Also went into loft and sealed the sarkin from the inside just to be sure.

As for the cornice i cleaned the stain off and sanded the paint back, going to stick some stain block on it then he can paint it or should i be doing something different?