Rendering Question

[vulcan800]

When ever I've seen people do rendering they have put a scratch coat on and left to dry out before putting on a fiinish coat and then leaving this coat to dry out before other work is carried out, i.e textured finish or painting.
A friend has had his extension re-rendered which was done as described above. now the workmen has come up unexpectantly when nobody was home and more or less took off the bottom half of the render right back to the brickwork, judging by the waste render left in the skip. They then appeared to have re-rendered all three coats in one morning - that is a scratch coat, finish coat and texture!!
My two question is: There must be a reason for rendering in stages so if you can do this application in one go then why do people do it over time?
Secondly, the new render is clearly much ligher in colour (almost white) so does anyone have an idea what they have done?[/img]

 

[roughcaster]

You are correct in what you say about rendering being done in stages and allowed to dry out between coats. That is the proper way to do it. You said that your friend had his extention re-rendered this way. You then said that the workmen came back unexpectedly and took the bottom half of the render right back to the brickwork, and then rendered/textured (tyrolean ?) it all out again in one go. Why would they do that? Maybe they did something wrong, to take it off and re-do it so quick while no-one was at home... Rendering is always best being done in stages, letting each coat set and cure, and then apply the next coat. Most plasterers/builders would do it this way..... Strange one this.

Roughcaster.

 

[vulcan800]

Thanks for the reply Roughcaster.
It's been a bodge from the start I believe. there has been about 7 different renderers doing this job. A scratch coat was put on and then a finish coat and then taken off completely. it was all redone including the cement/mix texture as if ready for painting and then windows and frames has were put in and the installer knocked off blown areas of render in the process. This is when the bottom half of the extention was taken back to the brickwork and a render was applied in one go.
Im concerned that putting render on in one go including the texture will cause problems in future although it does seem in better condiion than some of the render that was not touched on the latest re-render which sems to me to be blown in places.

 

[roughcaster]

Maybe it was because they knew they had a major problem with the render blowing away from the brickwork that caused the panic. If they were able to take the render off so quick and then do it again while the owners were out kind of proves that. Render doesn't/shouldn't come off that easy. Tell you friend to tap the render with his knuckles to see if it sounds hollow anywhere, especially above the windows where the lintels are..... Putting render on in one go wouldn't necessarily cause a problem for the future as long as it is keyed (scratched) properly to the brick/blockwork, but it could cause a problem for the person putting it on if became too heavy a coat, and began splitting/slumping,,,, as I said earlier, most would do it in 2 separate coats, on 2 separate occasions.

Roughcaster.

 

[roy c]

AS roughcaster says there must have been a problem with the "key" to the brickwork for them to come and take it off so easy. As for them putting the render on again and texturing/tyroleaning I would think that they only put one coat on and waited a while and "floated" it up. And then put the tex/tyr. coat on. It would be interesting to find out the thickness of that render coat. Iwas taught to leave 3 days inbetween "coats" to let the cement hydrate properly, and if the weather was warm or hot then we would constantly spray it with water thru the day after it had picked up and sometimes come back in the evenings to hose it down. I know of a case where a gang of plasterers came and scratched out a new
large house and tried to pull 2/3rds of the money off the job and the owner of the house said not till it was finished. These guys never came back. So he got another "plasterer" in I said to him are you going to knock the scratch coat off and start again? He said no he was going to float it out. I advised him to knock the lot off and start again,which he ignored.He stuck the beads and bells on with "drywall adhesive". And when I came back off holiday the joiner said to me ,"go and look at the rendering on the house". When I looked around the whole lot was cracked and coming off in sheets. Rendering is a system, and if you are following after some one else its best to start again and you then know what is in the mix what the s/c aditive ratios are. Also there are difference types of bricks and blocks and all have different suction properties and this seems like part of the problem the boys had doing your friends house.You can teach a person to render but it takes years before they understand all the complications of what can occur when you mix two simple things like sand and cement together and apply it to a flat surface...

 

[vulcan800]

First of all thanks for the replies.
I've seen enough now that I have persuaded the home owner to stop all work before they paint it. On my advice he is calling in a independant builder in to inspect it .
I'm going to meet at the house with this other builder later today to point out my concerns. One of my concerns, and probably the least of concerns is the general untidyness of the work, particulary of the corners and any edge that should be straight. A spirit level test of some perpendicular edges show them to be out by up to an inch in places.
Rather than make a fool of myself, I'd like to know whether they should have used some sort of beading on perpendicular edges to keep them neat.
TIA

 

[charlandy08]

I want to remove the old render from the back of my house. Is there a special beading needed, and can I render over where the damp course has been injected, as the brick work both above and below looks a mess.

Many thanks

ANDY

 

[Alastairreid]

calling in a independant builder in to inspect it .

no such a thing (if you are looking for impartial advice)
a surveyor more like.

charlandy08 dont hijack threads start your own

 

[charlandy08]

Sorry......

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