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DIY | DIY
brickwork | Re-pointing a wall
Often when you observe brickwork you
will notice that the cement from between the bricks has started to
fall out from the joints, this can happen on new brickwork but especially
happens on old brick or stone work. The cement between the bricks
is often called “pointing”.
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Driving water often penetrates the cement as it ages it often
becomes more porous, the water is absorbed by the cement and
when the temperature outside is low enough the water freezes
making it expand, this then forces the cement from in between
the joints, often leaving partial or full gaps between the bricks. |
Although this type of damage can be caused over decades, it is important
to repair the damaged pointing as soon as possible, either by repairing
just the pointing that has fallen out (patch re-pointing) or by removing
all the old cement on a large area and re-pointing the whole area.
Patch re-pointing is fine but if the amount of damage is large it
is best to do a full grind out and re-point (preferably before the
onset of winter).
Care must be taken when re-pointing as there are many hazards, working
at heights and using power tools. NEVER REPOINT FROM A LADDER Always
hire a scaffold tower or get a professional firm to put some scaffolding
up for you!
Personally I find re-pointing very therapeutic but others find it
boring and laborious, if you don’t enjoy doing it, then the end
job will probably not be satisfactory and perhaps it is best to call
in a builder or other professional. Don’t be surprised if you
get quoted a price of £500 to grind out and repoint the back
of a two bedroom terraced house as this is what a builder could charge
(don’t forget he’s going to need scaffolding etc.)
Safety is of paramount importance when doing a job like this! You
are going to be working at heights with power tools. Dust will fly
everywhere and there will be noise pollution also. Chiseling the mortar
from the joints is a bad idea as it causes too much vibration and
can loosen all the bricks.
I never use or recommend abrasive disks as these are considered dangerous,
they produce far more dust than Diamond tipped disks, are noisier,
harder to use and can sometimes disintegrate!
1. Scaffolding, access tower or cherry picker
2. A small Angle grinder (4.5 inch or 5 inch) with either a diamond
tipped mortar raking blade or a mortar rake attachment and dust guide
plate.
3. A couple of buckets, Pointing trowel, Possibly a brick jointer,
Finger pointing trowel, Large soft brush, Paint brush/ watering spray,
Safety shoes, Ear defenders, Industrial gloves, Head protection, e.g.
hard hat or bump cap, Sand, cement and hydrated lime or Mastic, PVA
bonding
If you are re-pointing a large area always start at the top, this
prevents dust from falling down onto the fresh re-pointing.
Using your angle grinder and diamond tipped disk remove the cement
from the horizontal joints but only to a depth of 10-20mm, then remove
the cement from the vertical, be extremely careful not to score the
brick as this will look amateurish, grind out the joints from approx.
Three courses of brick, the full width of the area that you are doing.
With a large soft brush, remove all the dust from between the joints
and then wet the joints with either a watering spray on fine mist
or with a wet paint brush.
Mix half a bucket or mortar, this should be measured accurately as
you want all the mortar to be a consistent colour! If you are using
mastic then use it in place of the mortar.
Mix to mortar to – 1 part cement, 3 parts building sand and ¼
part hydrated lime (this helps with movement and makes the mortar
less likely to crack). Also add some PVA bonding to the gauging water.
The trick here is consistency! Make it too wet and you will struggle
and get it all over the bricks, it needs to be pretty firm so that
if you press the mortar against the side of the bucket you can cut
it with the trowel like cutting a piece of marzipan with a knife.
The mortar should stand up on the trowel without sagging. Take your
time and ensure you do not get it all over the bricks as this looks
terrible. Repoint the horizontal joints then the vertical joints in
the area that you have just ground out. When you get close to the
next row of joints to grind out, put the cement somewhere safe.
Then grind out the same size area as you did before, then repeat the
pointing process until the whole area is finished.
There are several choices when it comes to re-pointing with the finish
of the mortar.
• Weather Struck
• Flush
• Strap (normally only used on stone)
• Concave (this is where the brick jointer is used)
• Recessed
The finished wall
Courtesy of Ultimatehandyman.co.uk
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