Is my render blown and what should I do

Cat in a hat

New Member
Hi
Last year i had a single story 12 by 4m extension built. The walls were rendered in April last year but due to problems with the patio the same builder was putting in, the render was not painted.
After a very long battle to get the patio done correctly and waiting until dryer weather we were finally getting ready to paint the wall render as well as a rendered retaining wall on the other side to the patio.
All the render on the build is chalky so I have been told to stabilise it. So I was brushing the walls to stabilise them and I found problems, areas the render just brushed away to 10mm deep with a finger

The company came out to repair issues with the render and while there i was standing against an end 4 wide wall and noticed tiny cracks. When I tapped the wall it was hollow. The guy (P) decided to repair it and chipped it off and said it was hollow and ended up with a 2 by 1m wide hole. He then put a single skin of new render on the area. A week later we were again by the wall and I found another area that was hollow. I tested the whole wall and a third sounds hollow when tapped, mainly by a gutter downpipe.

Another guy (M) from the company was out the next day and told me the whole wall was blown and needed replacing and that even the patch was no good probably because it was just one layer. The following day I got a call from the company telling me they were sending someone to patch the wall. I pointed out it all needed redoing and they told me that was not what their person (M) had said.

So (P) that had patched came out again. He looked at the wall and agreed that it sounded hollow and there were fine cracks in places but told me the boss said I should just paint over it. He even tried to tell me the reason it was cracking was because I kept tapping it. He said that he wouldnt patch the wall as it would just lead to more problems (by this time the area around his original patch was hollow too).

I was understandably not happy and after a discussion he agreed to try to persuade his boss that the wall needed redoing.

I then got an email from the boss telling me I needed to pay them and paint the wall and that if large cracks formed or the render cracked off the wall my guarantee would cover it.

So my questions are:
1. Is hollow sounding walls a sign of blown render or does it need to be large cracks?
2. Is there a standard i can quote to him for workmanship purposes.
3. What should I do now? Threaten legal action? I had to threaten that before he did the patio properly so I'm expecting this to be the case.

Thank you in advance.
 
Here is a photo of the wall. Green crosses show areas that when tapped are hollow.
 

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There is green mould aroud the down pipe? Staining under the copings and ground level.

The ground level staining can be avoided but the copings could be inadequate. As to what is causing the green staining needs to be looked into.

The green staining and coping issue needs to be rectified first ard no matter who re- renders this wall with whatever you will be back to square one in no time.
 
It's not actually green, that's just the light on it. There is an area showing where there was some green at the bottom. The render was done before the decking (same cmpany) and goes below the deck but not to the ground. But the water does seem to track up there. Should it have a bead above the deck?

We have there same issue by the retaining wall where the render goes below the drain that is next to the wall. Water tracks up. I did suggest the render went too low and should finish above with a bead but was told it was standard. I've used a fungicide on there for now and it looks better but I'm aware we could face problems down the line.

So a hollow sound is blown???
 
There is green mould aroud the down pipe? Staining under the copings and ground level.

The ground level staining can be avoided but the copings could be inadequate. As to what is causing the green staining needs to be looked into.

The green staining and coping issue needs to be rectified first ard no matter who re- renders this wall with whatever you will be back to square one in no time.
there is no green staining on the coping. The coping is weathered into the roof and I've not really seen damp showing down below it.

the retaining wall is another matter. They just used brush in jointing on the wall after the first solid joint failed (they mastecked the coping on then as it was moving). Even a small shower and we get water running down the wall.
 
Here is the rendered wall. I've fungicide it and scrubbed it clean but you can see the marks where we get issues. It's a long wall 18m
 

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