bad render

[franka]

About 21 years ago I had the rear face of my property re-pebbledashed.

I found over subsequent years that the finish was very hollow when tapped and it appeared that the whole of the finished surface was live.

I have recently had to replace some windows and while removing one of them a large sheet of the pebble dash finish seperated from the wall.

I have now decided to have the whole face redone and found it very easy to remove the top surface, simply prising it off with a stripping knife. The scratch coat however remains and is very weak. If rubbed with your fingers or scratched with a chisel it falls from the wall like dry sand.

My problem is how do I remove it. Scraping it off is not an option as it blows everywhere, including over neighbouring properties, also it would be a virtually impossible job to scrape the whole face.

Is there a way to seal it so that it can be floated over or would the finish be to weak to take the weight of the top coat?

If it has to be removed can someone suggest the way to do it.

Thanks for any replies.

 

[Lynn]

power wash it? At least water would keep the dust down if you have to knock it off the wall.

 

[Gervase]

That sounds a promising idea - if you've got a washer with an adjustable nozzle to produce a fan-shaped jet of water you should be able to 'chisel' the stuff off with the jet. And, of course, the wall would be nicely wetted to kill the suction when you put on some proper render.
Just try it on a small, inconspicuous patch first, in case you bricks are so soft that they turn to porridge under the onslaught of the water jet.

 

[NT]

It does need to come off if you rerender, or you'll just repeat the same problem. Once all off I'd consider insulation. If you rerender direct and its an old property you really should use lime, cement is going to damage the wall in time. This lot wont have caused damage, as its too weak to do anything, but thats not much use.

I would be a bit cautious with a power washer, good chance it'll rip the mortar between the bricks out, and if that happens it could in the worst case bring the whole wall down.

May be safer to look at a plastic filament rotary brush with hoover spout up close, using a hoover spout attached to a drill sucks up at almost all the dust.

Also a lot of it may just break off in lumps.

Patching it would be a whole lot less work.


NT