Feb 02
I want to flat render an already pebbledashed wall. The wall is sound and would like to know how to prepare the wall to do this?
I want to flat render an already pebbledashed wall. The wall is sound and would like to know how to prepare the wall to do this?
Hi. The key here is to apply new render in a few layers. The “pebbles” of the existing surface will not be absorbent so its a great idea to get as many of them off as possible. We use the back of a heavy rake to run over the wall taking off the existing pebble surface. Many companies use the heavyweight version of PVA called SBR on the wall as extra adhesion but this does allow the wall to breathe and, if there is any damp trapped in the existing surface, this could lead to problems in the winter when everything freezes and expands (see our DIY Projects page on Freeze-Thaw action).
The stones also cause a problem in so much as they do not allow the render to be aplied in an even thickness so it is important you get as many of them off as possible.
Once the pebbles are off (or as many as possible) damp down the wall by flicking water onto it from a large brush, then render a thin 3-8mm coat working well onto the existing sirface to give you a flat surface. Scratch this coat lightly and then apply a second thin coat while the first is still damp (not wet). scratch again and leave until ready for top coat.