One item that we need to cover may be useful right away. That is the
method or pointing, or in some cases, re-pointing. If you have
existing stonework from the 1700's to 1800's that has been plastered
over, this may apply. It is very common in our area to remove the
plaster and repoint the stonework. There are many farm houses in
Pennsylvania that fall in to this group. Depending on a few
variables, the price range for chipping, sandblasting and repointing
goes between $5.00 to $6.50 per square foot. It can get expensive on
a large house rather quickly .
If the stone is rather clean on the areas that you would like to
repoint, you can bypass the chipping and sandblasting. You now need
to clean out the joints to about a depth of about 1" or slightly
more. Chip the joints using a hammer and chisel , or a small air
hammer if available. The automotive muffler type works well for me.
Wear safety glasses and dusk mask for this operation. Also, if you
use a air hammer, a light spray of water on the wall before you start
really cuts down on the dust. These older homes were built with stone
walls about 2' thick. Basically the only materials used where stone
and clay. The walls were originally meant to be plastered over, not
exposed . There will be many very small stones jammed between the
larger ones to fill up the voids. Many of the larger stones may be
resting directly (stone in contact with stone) on other stones
without any joint between them. This is the one point at which you
can rush though the job, or take your time and really make that
little difference which gives you "that's really beautiful " look.
The very small stones, about 1/2" to 1" by 2" to 3", knock them out.
Your looking for a joint size between stones to be about 1/2" to 1".
If two stones are touching each other, using a hammer and chisel ,
cut away trying to obtain that 1/2" joint line. The main idea here is
to have a complete joint around each stone, and have the mortar not
stick out past the face of the stone. This is called recessed or tuck
point. It includes over 95% of the pointing style that we do, even
with the new construction.
The joints are now picked and chipped clean. Now brush out any loose
material. The mortar that you will repack the joints with will be 3
parts of bar sand and 1 part portland cement. You can use a premixed
mortar mix from a building supplier. But just a note here, as a
stonemason, I do not use lime in any mortar. Brick and block masons
use a even mix of (1 part) cement and (1part) lime with 6 parts of
sand. The addition of lime into the mix makes the mortar slightly
more plastic in form, but it does not get as hard as cement and sand
only mix, when dried. For a cement and sand mix only, use 1 part
cement to 3 parts of sand.
A power mixer does work best, but in the event you must do this by
hand (a hoe of course), mix the sand and cement thoroughly before
adding any water. Then, mix the mixture adding water till you get the
consists of soft margins . It should not be runny, but wet enough to
maintain it's shape when squeezed in your hand. This evens varies
between masons.
The tool required for packing the mortar is a tuck pointing trowel.
Using a brick trowel or hawk to hold the mortar, pack the mortar into
the joints using the tuck pointing trowel. This is the part that
really takes the time to learn. The horizontal joints go pretty well,
it's the vertical that can cause a beginner some grief. When you get
the mortar on the brick trowel, pack it tightly with the tuck
pointing trowel into a few horizontal joints. Now, make a slice in
the first 1/2" mortar, and slide the tuck pointing under that 1/2"
section. Now lift up the pointing trowel without tilting to either
side. Once you can make that little slice and keep the mortar on the
pointing trowel, you kind of flip it into the vertical joint. Like I
said, this does take a little getting use to. One thing about that
pointing trowel, get the kind that's thin and has some spring in it.
Not the cheap ones that are thick mild steel. They come in sizes from
3/8" to 1" wide, about 1/16" thick. The better ones go between $7.50
to $10.00. There about 7" long.
Pack the mortar between the joints trying to stay off the face of
the stone. You need not overly concerned about the looks of the
joints at this time. Just get the joints packed tightly. Now,
depending upon the weather, keep a eye on the very first section that
was pointed. This may take from 1/2 hr. to 2 hrs. Go over the joint
lightly with a wire brush testing to see if the mortar smears on the
stones. When it dries to the correct point, you can brush the mortar
to a even surface which is slightly recessed from the face of the
stone. You want to show the detail of the edges of the stone. I take
a regular long handle wire brush, and cut off the handle, and then
cut what's left in half again to make two small brushes. Use light
quick strokes and you should be able to get the surface of the mortar
rather flat in appearance . These same basic steps can be used to
repoint brick walls or chimneys which are badly weathered.
How the human eye and mind perceives images is very important here.
Brushing the joints to the point that the edges of the stone show
will cause slight shadows to form. It is the presents of these
shadows that give the mind the information needed to create the true
three dimensional look into the wall. The detail also shows the time
taken by the mason and that information is automatically added into
the entire picture. It is not always just what we see, but what we
perceive created what we see. The eyes and mind work in beautiful
ways.
When removing the plaster from a older building, it is not that
uncommon to find areas of the walls which have some stones which are
very loose. Large cracks, bowed walls, and uneven window sills maybe
signs of structural problems. An inspection by a professional is a
must if you have any uncertainties about structural conditions.
Safety First... Keep everyone clear of falling plaster and stones.
On buildings with interior fireplaces and chimneys , it is common to
find the stone wall at the gable peek to be very narrow where the
chimneys goes through the roof. Care must be taken when chipping in
this area. In many cases, the chimney section above the roof is built
of brick with this style.
Another area which requires special attention is above and below
window openings in the wall structure. The decay of timber supports
may have a loosening effect on the stones. Headers may have to be
replaced, and the stones in these areas may need to be reset.