Any Plasterers Here? Problem With Bond & Set...

danza · 16 Jul 2011 at 17:35

If any of you have experience of plastering, please can you comment on this? I've been recommended this particular plasterer by about a dozen people who I know (not by other people in the trade), and have seen some of his work which to all intents and purposes is excellent.

He did the ceiling of one of our bedrooms on Wednesday, and it's fine. However, yesterday he did the walls of the same room, and hundreds of hairline cracks have appeared (as per the picture). In the worst case as seen in the picture, the plaster is coming away and actually moves when touched. The actual finish (apart from the cracking!) is incredibly good.

I don't want to tell this guy to sling his hook quite yet as he comes so highly recommended and it is intended that he will also be doing quite a lot more plastering around our house in the next few weeks. What is the likely remedy to this? Will it all have to be raked off and re-plastered? Any suggestions would be gratefully received.

kmufc77 · 16 Jul 2011 at 17:41

Hi

Im a Plasterer (See profile

) by the looks of it the plaster (Thistle Multi Finish) has dried too fast,did he apply PVA (Unibond) on the walls to seal first? NO NEEDED if backing is plasterboard!

If the backing plaster ie: hardwall/bonding is left too long like skimmed the next day or later,the finish plaster multi finish drys really fast and thats why you need to apply PVA onto the wall.

If he skimmed onto the backing plaster the same day as you can with hardwall,then he hasnt troweled up in time with the plaster setting if that makes sense.

Did he skim onto walls thats were painted etc or onto a backing plaster usually called thistle bonding or hardwall?

Or he hasnt trowel the walls in time with the plaster setting. ie left the plaster too long before applying the final trowels

Edit:

By looking at the pics the plaster has 100% dried too fast and not been troweled up into with the plaster setting ,the questions above will help me know why.

If you have hundreds of those hair line cracks,you will need it re-plaster for sure.

dodgem · 16 Jul 2011 at 19:04

I'm not a professional plasterer, but i have skimmed most of the walls in my house to a pretty good standard. As above, it looks to me exactly like he has not applied pva to the backing plaster underneath. This causes the water in the finish coat to be sucked out and it dries so fast it cracks like that. Happened to me on a window reveal in my kitchen - i immediately scraped it all off, applied pva and replastered with a great finish

ExecutorKevin · 16 Jul 2011 at 19:05

I would just buy a new house

kmufc77 · 16 Jul 2011 at 19:08

dodgem said:
I'm not a professional plasterer, but i have skimmed most of the walls in my house to a pretty good standard. As above, it looks to me exactly like he has not applied pva to the backing plaster underneath. This causes the water in the finish coat to be sucked out and it dries so fast it cracks like that. Happened to me on a window reveal in my kitchen - i immediately scraped it all off, applied pva and replastered with a great finish

Havent i already said that ?

Mark A · 16 Jul 2011 at 20:21

It's happened to me before but I think it was due to using board finish onto sand and cement render in a kitchen (as it's all I had). I had even used PVA on the render but it still cracked.

dodgem · 16 Jul 2011 at 20:54

kmufc77 said:
Havent i already said that ?

dodgem said:
As above, it looks to me exactly like he has not applied pva

Yes. Haven't I already credited you?

Just more confirmation for the OP - i'm sure he will be happy with more than one opinion

kmufc77 · 16 Jul 2011 at 21:45

Mark A said:
It's happened to me before but I think it was due to using board finish onto sand and cement render in a kitchen (as it's all I had). I had even used PVA on the render but it still cracked.

Using board finish on sand and cement compared to standard multi finish will make no difference.

The only real difference with board finish is it sets a bit quicker than multifinish,as multifinish hangs around a bit longer when using it on plasterboard.

The sand and cement backing was more than likely left too long and not enough PVA (strong enough) was applied to the wall,and thats why it cracked,too much moisture sucked out of the wall..

Ideally when a sand and cement wall is floated up.waterproofer/retarder needs to be added to the mix of sand and cement,this holds moisture in the wall when skimming and stops cracking and drying out too fast.

When i float sand and cement walls ready for skimming i make sure they are skimmed the next day or the day after at the very latest,no PVA is needed this way as there is moisture in the wall still