mapping on render and set

[naz]

ok my old man has just rang and asked me what i think it is so i thought ide come on and see what u guys think.

basicaly he rendered 2 rooms and in each room 1 wall has mapped and the paint will not stick even if u splash water on it the water just runs off, i used to get it above the doors where the lintels are but i aint had it for ages, it aint over troweling it coz my old mans done it for 45yrs.

if it was the sand it would be on other walls aswell the same if it was the plaster.

any ideas guys?

 

[church]

what was he rendering over and was the cracking on a door frame wall ?

 

[naz]

just over block work no door frame but it aint cracking its wierd but its repeling any water or paint, the builder tried sanding it but the paint would only stick where the sand paper has scratched

 

[del]

Sounds like someone is telling pork'y pies, probably the builder sealed it with pva or something. ???

 

[naz]

nah u can see sumin aint right with it

 

[Liam Murray]

the walls that are affected are they back to back

 

[naz]

no totaly different walls, one upstairs and on downstairs

 

[Nisus]

Strange, could it be waterproofer bleeding through from the render onto the surface?
Don't think this would happen but it's the only thing I can think of, that's if waterproofer was used?
Or like already said has it been sealed with summat?

 

[naz]

i think my old man uses waterproofer but its srtange why its only affected 2 walls

 

[Nisus]

If the paints sticking where it's sanded they'll just have to sand the 2 Walls before painting.
But that doesn't solve the mystery for your old man.

 

[naz]

no its a wierd one

 

[spunky]

poss try reskimming it if it was a dodgy bag of finish................ive used plenty of w/proofer in my renders before and skimmed and not had a problem, was it a damp wall before you started or has it got damp from the other side?.........defo a strange one mate ???

 

[NRM2007]

I did a barn conversion not long ago mate, and the painter was moanin saying that the paint just would not stick in some random places, this was skimmed onto board, he reckoned I'd been using PVA??????? I said there was absolutely no chance had I used PVA on boards, he then realised I was being genuine and we've still not come up with anything?????? seems strange you've had it aswell. dodgy finish maybe??????

 

[naz]

yeah it is a real thinker, i used to get it every time when it was onto a lintel. no damp anywhere

 

[roughas]

something in the water when troweling up ???

 

[bodplasterer]

Yeah we had this in a basement we did last year but we were using dri-coat it was weird as it was only a small random patch ???

 

[naz]

its frustrating coz it could be lots of things but why only 2 walls

 

[specific]

on sitework some years ago,we had the same problem,after a lot of head scratching i had a look in one of the water butts and on the surface there was a film of oil/diesel,laying on and trowelling up was no different so we wouldn't have noticed,the water butts were the only thing we could point it to,because some walls were ok(different water butts).

 

[Philby45]

I have had it myself, but only occurs on light weight blocks, but gives the same result as overplastering

 

[bodplasterer]

Ahh it all makes sense now some one told me the other day that if you paint diesel on the wall paint wont stick to it and totally fucks it up he also said he wanted to try it out if some one didnt pay him ;D

 

[oasis]

i keep gettin bad multi bags this week, when i come to trowel up it starts ripping and draggin even with water?

 

[spunky]

it happens every year at this time mate ;D......give it a month and itll be gone