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.

I thought I might try limewash as a finish.

* Which is always what happened when I tried pebbledashing.

Andy.

Andy.

Andy wrote:

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.

How rough do you want your roughcast?

The much of our place is finished with a roughcast / stipple render, and
when I was doing the new gable end for my loft conversion I wanted to
match it. I found I was able to get an almost perfect match by simply
rendering the top coat as normal, then then giving it a firm tamping all
over with a stiff dustpan brush.

see bottom two photos on this page:
http://www.internode.co.uk/loft/rendering.htm

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.

I thought I might try limewash as a finish.

One thing I found is that new rough render is a PITA to paint!


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"John Rumm" wrote in message
...
Andy wrote:

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.

How rough do you want your roughcast?

The much of our place is finished with a roughcast / stipple render, and
when I was doing the new gable end for my loft conversion I wanted to
match it. I found I was able to get an almost perfect match by simply
rendering the top coat as normal, then then giving it a firm tamping all
over with a stiff dustpan brush.

see bottom two photos on this page:
http://www.internode.co.uk/loft/rendering.htm

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.

I thought I might try limewash as a finish.

One thing I found is that new rough render is a PITA to paint!


--
Cheers,

John.

Thanks for that John, I'm impressed, that looked like a big job!
It's not easy to tell how much texture you achieved from your photos, but
I'm looking for quite a lot, so I may try the roughcast route and see how it
goes.

I've had problems already, listened to a neighbours advice, and left the
battens on overnight: of course when it came to pulling them off I pulled
off/blew quite a bit of the render undercoat. I had to go around tapping the
render with my knuckle to find the detached areas and chop them out and
renew. He also said that I didn't need to scratch the undercoat as the
texture from using a wooden float on it would be enough to give the topcoat
a key, but I'm thinking he speaks with forked tongue now!

I think I will practice roughcast on a piece of plasterboard. For the
curious, my wall has exposed red brick-and-a-half piers capped with a thick
( 4.5" ), flat-topped cast concrete coping painted white, blockwork finished
( hopefully ) with roughcast ( limewashed ), and the wall finished with 1.5"
Welsh slate coping.

Andy.

When you say roughcast do you mean tyrollean rendering? This is done by
splattering a suitable mix with a hand cranked splattering machine (about
£50 from Screwfix).

"Newshound" wrote in message
...
When you say roughcast do you mean tyrollean rendering? This is done by
splattering a suitable mix with a hand cranked splattering machine (about
£50 from Screwfix).

No no, I've examined the Tyrolean angle but don't find it offers enough
texture*.
Roughcast is sand and aggregate up to 3/8": thanks for the info anyway.

*Getting all philosophical, I've noticed one of the things in architecture
that is usually present in attractive structures is textu multi-coloured
bricks, variation in slates/tiles, rough-rendered walls etc.

Andy

Andy wrote:

Thanks for that John, I'm impressed, that looked like a big job!

Twas about four days to do all the render IIRC (including stuff like
buying materials, cadging a cement mixer, and fixing all the corner
profiles and drip beads etc).

It's not easy to tell how much texture you achieved from your photos, but

Probably not as much as it sounds like you want then. The best photo I
can find that gives some idea is this one:

http://www.internode.co.uk/temp/texture.jpg

I'm looking for quite a lot, so I may try the roughcast route and see
how it goes.

I think I will practice roughcast on a piece of plasterboard. For the

Sounds like a good plan....

curious, my wall has exposed red brick-and-a-half piers capped with a thick
( 4.5" ), flat-topped cast concrete coping painted white, blockwork finished
( hopefully ) with roughcast ( limewashed ), and the wall finished with 1.5"
Welsh slate coping.

Stick a piccie up somewhere when done so we can all admire!

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

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

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..?

The Natural Philosopher wrote:

Surely that is the dreaded pebbledash..?

Depends on the region. In the midlands the pebble dash is litterly dry
pebble thrown at the wet top coat so that the pebble remains exposed.
In Scotland rough cast is termed Harl. I tend to think of rough cast as
being the wet mix thrown at the scratch coat. Mind you I have no doubt
that regionally the mix will vary as will the technique. I know that
you cannot find many people who will carry out such a messy job.

Regards
Legin

legin wrote:

The Natural Philosopher wrote:

Surely that is the dreaded pebbledash..?

Depends on the region. In the midlands the pebble dash is litterly dry
pebble thrown at the wet top coat so that the pebble remains exposed.

In Scotland rough cast is termed Harl. I tend to think of rough cast as
being the wet mix thrown at the scratch coat. Mind you I have no doubt
that regionally the mix will vary as will the technique. I know that
you cannot find many people who will carry out such a messy job.

Except, perhaps, in Scotland. We had some harl done last year on an
upstairs gable wall - lovely job, completely uniform with no patches,
and it has set like iron. As Legin says, this is wet-mix, not
pebble-dash. The surface finish is the uniform grey mix colour, with no
loose pebbles whatever. The rough texture does exactly what it's
supposed to, encouraging the water to fall off the wall in drips rather
than running down in sheets.

I wasn't here at the time, and have no idea how the builder got it all
to stick on the wall, leaving nothing on the window-ledges or the ground
beneath.

As John Rumm says, it's a PITA to paint... and a right royal PITA to
drill accurately. The only way I've found is to mark the wall, level off
the stones very carefully using a small cold chisel, mark again, and
"centre-punch" the holes by hand with a small Rawldrill.


--
Ian White