legin wrote:
Andy wrote:
Folks,

My boundary wall-building programme has reached the point where I need
to
think about finishing off. I've rendered the wall with a 1/2" of lime/cement
mortar either side, and that is going off e'en as we speak.

As I understand it roughcast involves making up a sort of concrete made with
small aggregate (3/8" down to sand size ) and flinging it at the undercoat
of render.

Anyone done this? Any tips? I figured on getting a small fire shovel,
loading that up and flinging it from a great distance, varying the angles of
application to get an even finish, sounds good in theory but what about in
practise. I'm worried the roughcast will bounce off*, presumably I may need
a thin (1/4"?) topcoat render layer to fling it onto, and I'm going to try
and keep that wet by spraying, so the roughcast sticks.

Extremely messy job but can look stunning when done right. For best
results it is "thrown" at the scratch coat. If you have already applied
1/2" render both sides then the weight is probably going to pull it off
the wall.
Jobs I have done have been 3 and 1 scratch coat. Rough cast mix made of
1 cement 2 sand and 2 stone ( last job was cantebury spa, previously
have used granno dust but sometimes all dust and no body).
The mix needs to be wet, almost runny. If it is too stiff it will stick
to the walls like clumps and will be very patchy. Try small areas and
scrape off until you get the mix right. If you get a good runny mix
then when you fling it at the wall it will splat and even out the
surrounding areas that have already been rough cast. Not too runny it
will all slide down the wall.
Good Luck.

Regards
Legin

Surely that is the dreaded pebbledash..?