Cleaning rendering / roughcasting.

[crapday]

I live in a 1960 john lawrence house in the Glasgow suburbs. The outside walls have been "pebble dashed", what I would like to know is, can I wash the rendering with a jet spray ?. My next door neighbor's walls are really clean and mine look dirty in comparison. They have lived there for 9 years and us for 11 years, in that time they have not had their walls cleaned so I can't ask them how their wall seem to be cleaner.

If I can't jet spray the walls then is there another way to clean this type of finished wall surface.

cheers Gary.

 

[noseall]

there can be noticeable differences between windward and leeward sides of a building, also location of say a tree can have an effect as to how a building can weather.

south facing elevations are generally cleaner and moss free whereas north or east facing equivalent walls can be a lot more 'weathered'.

 

[allanlaw]

Did you manage to clean the roughcast? What did you use?

I have black marks over my walls (believe to be oxidation) and looking to clean.

Ive heard that you can get the pebble dash acid washed, is this true, and can you buy it from B&Q etc?

Do you need to get rid of the oxidation before you can paint the pebble dash walls?

cheers

allan

 

[roughcaster]

I would be very careful trying to wash roughcast with a power washer. It would probably work but at what cost. If it caused damage to the r/cast then what? With rendering it would be easier, but still worth testing an area first. If you do go for it, better maybe to use it as a spray from a few feet away, rather than too close with the jet. Once you've started, your commited.

Roughcaster.

 

[allanlaw]

Roughcaster,

Can you suggest any chemicals or acid to use, as water it self hasn't worked, many thanks allan

 

[corrie]

Lawrence houses of that era have drydash with Durite or similar. As Roughcaster says you can`t put the power on it as you will remove chips. Do a very small test sample. If it is mossy or algae type dirt try a Fungicide. If road dirt try washing Soda or similar. Spray on and spray off only. Those little weedkiller sprays are ok.

If it`s spoiling your property you can overdash it with suitable method for a "new look" provided roughcast is sound and you have room on the detail to avoid any proudness issues of the new cast.

Alex

 

[roughcaster]

Hi Alan,
Just read your post. No, i'm sorry I can't suggest any chemical or acid for your situation, although others might know of some. As Corrie suggested, you could always roughcast over what you have to smarten it up, but there would be a substantial cost involved,scaffolding etc. Hope you can find some products that will do your job.

Roughcaster.