Dry Dashing
09/04/2015
Dave Winchester Jan 2011
10 thing you should know about external finishes
1 Poorly graded sand should not be used on external
rendering because it results in a weak mix
2 You can test for the silt content by using a jar of
water
3 To aid workability and create suction lime is often
used
4 A liquid plasticiser can be used in a mix in order too
aid workability
09/04/2015
Dave Winchester Jan 2011
5 A bell cast or render stop bead is used to defect water
away from the building, and are fixed above the doors and
window, also at the bottom of the wall above the damp
proof course
6 Cement is used as a binder for external rendering
7 Ordinary Portland Cement is used for external finishes
8 Mix proportions for external rendering can be
accurately measured by using buckets
9 Sand is an aggregate used in external renderings
10 A strong render must not be applied toa weak
background
09/04/2015
Dave Winchester Jan 2011
Dry Dashing
• Dry dash (also referred to
as pebble dash or
pebbledash) gives a fresh,
hard-wearing, waterproof
finish.
•
http://www.youtube.com/
watch?NR=1&v=AbYg2jmF
8tk&feature=endscreen
09/04/2015
Dave Winchester Jan 2011
Dry Dashing
• If applying directly to
existing brickwork
/blockwork / render
surface, the substrate
must be brushed down to
remove any friable
material, algae or lichen
and fungicidal wash should
then be applied
•
Stabilising solution may
be applied if required to
help improve adhesion and
offer uniform suction
09/04/2015
Dave Winchester Jan 2011
Dry Dashing
• Install all beads and trims
using approved fixings at a
maximum of 300mm
centres (depending on the
substrate
• Bellcast are formed to
direct water away from the
face of the wall
• Bellcast may be formed
without beads by using a
timber former
09/04/2015
Dave Winchester Jan 2011
Dry Dashing
• Lightly scratch basecoat
surface of a ratio of
• 4 parts sand , 1 part
cement, and containing a
integral Waterproofer
• Using a scratch comb to
provide a key for
finishing coat and allow
to dry.
09/04/2015
Dave Winchester Jan 2011
The correct mix for a butter coat is:
Dashing
6 sand : 1Dry
cement
:1 lime
Before applying the pebbles to
the wall area leave a sheet at
the base of the wall to catch
the pebbles, which will fall to
the ground
Using a dashing paddle throw
the pebbles at 90˚ to the wall,
do not throw them at any
other angle as this will cause
an uneven appearance on the
finishing surface
09/04/2015
Dave Winchester Jan 2011
Dry Dashing
Second coat (butter coat
It is essential that all the suction is killed off
before the butter coat is applied.
This will allow the pebbles to be thrown onto
soft materials
09/04/2015
Dave Winchester Jan 2011
Dog toothing
This is used when we
cannot complete the area
in a day work
At the end of the day’s
work cut the pebbles back
in a zig zag pattern
Make sure the cuts are
greater than 90ºin order
to get into the angle and
apply the butter coat the
next day
09/04/2015
Dave Winchester Jan 2011
The finished appearance of a dry dash finish will vary
based on the aggregate used in conjunction with the
underlying dash receiver.
http://www.pebbledashing.com/pebbledashing-aggregate-colours.php
09/04/2015
Dave Winchester Jan 2011