Rob_Impreza99

iTrader: (3)

Steve, just a quick question.

When someone cement renders the walls, how long should they leave it to dry before they skim it ?

stevebt

iTrader: (8)

as soon as its hard enough, you could do it the same day if it dried in quick enough. The only difference would be that the finish would take foreevvvvvver to set


Just out of curiosity how did he prep the walls 1st?? and did he use a 5-1-1 mix as I always say

Rob_Impreza99

iTrader: (3)

These are the materials he used for the cement render, he had to go back and too wickes a couple of times.

http://www.wickes.co.uk/Building-Sand/invt/220129

http://www.wickes.co.uk/Blue-Circle-Cement/invt/224661

From memory he started on the ceiling first which had artex on, he scraped that then skimmed it. Next he started on the cement rendering, he used one bag of wickes sand to one spade full of wickes cement. I should know as he had me labouring for him for free by mixing the sand and cement in a mixer what he had hired, before it went into the mixer he counted how many spades of sand were in the bags and i watched and it was six. I said to him shouldn't it be a 5-1 mix as thats what i'd read on the internet, he said it will be fine.

The process for the cement render was to put a bit of water into the cement mixer and a bit of washing up liquid, i showed him exactly what i was putting in and made sure he said thats ok, so it was 1 bag of sand to one spade full of cement.

He started rendering the walls, when he had finished one wall he would use this block with nails in to do circular swirls on the walls. On day 1 he didn't quite finish the room of rendering, he had the ceiling skimmed and 2 walls of rendering done. On day 2 he finished off the other walls in render then he went back to the first wall he rendered and skimmed that, on day 3 he finished skimming the other walls.

I can't be 100% certain here but i think he used PVA on the old grey plaster at the bottom but not sure if he PVA'd the render, it looked a very watery PVA that was pure white. I was expecting it to be more glue like, he just put it on with a paint roller and it looked little more than coloured water.

As i said, i can't be certain or not whether he PVA'd the render or not. The majority of the cracks have appeared where it was rendered, i'm not sure if their are any on the lower part where the solid grey plaster was. I'll look later.

Rob_Impreza99

iTrader: (3)

Ive had a quick look and counted 12 areas where their is signs of cracking, some more advanced than others. 11 of those cracks are on the upper part above where the grey plaster was where the walls were rendered, only one hairline crack is below on the grey area.

Their could be more areas as i'll need a ladder to look, ive only checked the areas thats in sight.

stevebt

iTrader: (8)

To be honest I was expecting you to say he uni- bonded the brickwork 1st so we could say ahh theres your problem

Bloody hell 3 days to do that little room It still has to be down to application as the render has to be loose to have those sort of cracks.

stevebt

iTrader: (8)

**** me how tall is the room that you need a ladder to check

Rob_Impreza99

iTrader: (3)

Do you remember the small damp area that appeared just under the window that i posted on the other thread, we got a surveyor out to check it and he was of the opinion that the render needed and plaster needed to be cut back as it breeched the damp course. He said that excess water internally between the floor and the wall was the cause, their is a small gap between the floor and wall where water could have held up when it was rendered and plastered. That then slowly seaped through the floor area, he did splash a fair bit of water about on the walls before he rendered them.

Now when i was cutting back the render and plaster by a couple of inches i couldn't believe how crumbly the render was, the skim is only wafer thin as well, i know its only meant to be a thin skim but i was expecting a little thicker to be honest.

alanbell

iTrader: (6)

I told you he had breeched the damp proof course and to cut it back,
And I told you his mix was to weak.

Rob_Impreza99

iTrader: (3)

I'm considering knocking the lot off including the render, ive no confidence in this lasting any period of time. If so many cracks have appeared now i'm concerned that once its decorated and carpeted with all the furniture in i could end up having the carpet and other fittings ruined by on going repairs.

I'd be willing to write around £600 off and put it down to experience, i just want a proper job done which it seems is very hard to find these days as finding a decent trades person is like hoping your numbers come up on the lottery.

stevebt

iTrader: (8)

If the render is crumbly its probably cause you only put one shovel of cement to one bag of sand. I have never mixed sand and cement in years but would of thought you needed more than that. If its deffinately a damp room plaster it in renovating plaster as its specifically meant for damp proofing


There is lots of people out there that claim to be plasterers cause they have picked it up from working with someone for a while. The state of the work I see when people come to have a go at doing the houses is laughable

stevebt

iTrader: (8)

If the render is crumbly its probably cause you only put one shovel of cement to one bag of sand. I have never mixed sand and cement in years but would of thought you needed more than that. If its deffinately a damp room plaster it in renovating plaster as its specifically meant for damp proofing


There is lots of people out there that claim to be plasterers cause they have picked it up from working with someone for a while. The state of the work I see when people come to have a go at doing the houses is laughable

alanbell

iTrader: (6)

Steve I do loads of rendering and full damp proofing, sand and cement done right is far better than any renovating plaster , imo