This is a well-built masonry stone retaining wall
Welcome to our article, DIY Retaining walls.
Dear readers, in our previous articles, we have talked about how to build houses, now, let us talk about retaining walls. It is going to be a long article, because there are many types of retaining walls. anyhow let us see why we need retaining walls.
You see, most
people that own a standalone house, want to improve their property by doing a
few things in the yard, where they can stay outside and have a garden, or have
a barbecue with their family and friends. But there are times when it is not
easy to stay outside, because the yard is not level and, in some places, it is
hard even to stand up straight, so, something needs to be done to improve the
situation. In this case retaining walls can help solve that problem. But how do
we build retaining walls one may ask?
Before we answer that question, let us talk about this well-built stone retaining stone wall shown here in this article, I reckon that it is a well-built
stone wall, but a wall like that is very costly and hard to build, unless you
are an expert and know what needs to be done.
So, let us see what we can learn from this stone wall
picture, just by looking at it and trying to imagine how this wall has been
built. What we can note from the picture is that the retaining wall has been
built leaning towards the bank it is holding up, we can see this at the right
end of the wall where the wall goes around the corner, the stones are laid dry as there is no sign
of any mortar around, the stones are not all the same size, and they are longer
and shorter stones, but they are all the same thickness and they are laid the
same way as we lay a course of bricks, but at the same time the mason has made
sure that the vertical join are not setting one above the other, and this is a
hard thing to do with stones all different size, everything is so tidy, the
wall thickness is not shown anywhere, but because there is a very low wall
started near, it seems that the wall has been built like a double brick wall,
we can also guess that perhaps some of the short stones are not really short,
but they have been laid like a header brick to tie the front with the back of
the wall, at the top the last course of stone, the stones are longer and as
wide as the whole wall itself, so that they would tie everything together.
These are the main features that we can learn from looking at this stonewall
picture.
Now that we have explained that, let us write how to do it
yourself retaining walls. You know, there are many types of retaining walls,
some are easy to build others are hard to build, and there are many reasons for
building them. So, this article is going to be a long article, because we want
to tell you about them, as much as we can.
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How to build retaining walls.
Okay, there are several ways how to build a retaining wall,
and there are several types of retaining walls that we can build. Therefore,
first we must see what we gain by building this type of retaining wall, or that
type of retaining wall, and above all how much it could cost, before we can
decide what type of retaining wall to build. Now we want to build our retaining
walls with building materials that are easily available, to avoid extra cost. So,
look what local materials are available, where you are. You see, if you are in
a place where stones or rocks are plentiful, and you may even have some of them
in your yard, then it is cheaper to build your retaining wall with these
materials, and even if you have to buy the lot they are cheap anyhow; but if
you are in a place where there are plenty of trees and there is even a sawmill
nearby, then it is more appropriate to build it with timber.
Having said that, it is obvious that for you to decide, what
is the best retaining wall to build; we need to explain to you what could be
done and how can it be done. Therefore, hereunder we will try to do that. Let
us start with a very easy and cheap retaining wall that most people can do
themselves, even if they don’t know much about building, as long as they have a
few tools and know how to use them; here we are saying that anyone of us can dig
a few holes in the ground to place a few short posts and place a couple of
sleeper timber planks against those posts, then secure them by nailing or
screwing them to the posts. It sounds and is simple, isn’t it? But this is not
the only retaining wall that we want to show you, so, keep reading this article,
while we add more descriptions, because you can even learn how to build them.
Timber sleeper retaining walls.
Building a low timber sleeper retaining wall is easy, just
about everybody can do it, you can do it yourself, if you follow our
explanation in this text here, all you need is a crowbar, a post hole shovel, a
hammer a few long nails or screws, a saw, a type measure and a few treated pine
sleepers that today are easily available at most timber yards.
If you are in Brisbane Australia, these are a couple of
addresses of local timber merchants and hardware to get what you want. If you
are somewhere else, you need to find your own.
http://en.wikipedia.org/wiki/Bunnings_Warehouse
Now, let us assume that you have visited your local supply,
and you have got all you need, so, you are ready to start, you have also worked
out where you want your sleeper wall to go; So, start digging the first hole
where the wall starts, you need to dig this hole about 600 mm or more in the
natural ground for the post to be strong enough to hold the pressure of the
retaining wall when the wall is back filled; you may have to concrete around
the post for extra strength, but this is not a must do, if the retaining wall
is low, because you can replace this with, packing the soil tightly around the
posts and if you have some rocks, wedge them between the top of the hole you
have dug and the post at ground level, because the rocks will exercise their
pressure on a larger surface of the natural soil than the post, they will be
able to hold back the soil pressure of the wall more easily, now that you have
done the first post, you can repeat the same procedure for next post and so on.
The posts can be made from the same material of the
sleepers; you can saw them to the right length and fix them in the ground as we
have said above. Now, to make it easy let us say that your wall is going to be
the length of a sleeper plank, and you have dug the two holes and fixed the two
posts. So, now you can just place the first sleeper against the posts at the
required level; the levels of the sleepers is better if you work it out from
the top down, because it is easier to change the bottom than the top, you see,
in this case you can always dig a bit or add a bit of soil at the bottom to fit
the bottom sleeper. So, mark on the posts the level you want to reach with your
last sleeper and then mark down from this level the number of sleepers you are
fixing on these posts, once you have done that you are ready to fix your
sleepers on the posts.
Fixing your sleeper to the post.
To fix the sleepers to the post now is simple, but still you
need to do a few things right, if you want your wall to last a long time, with
the materials you are using now; it is useful to know that in this case it is
highly advisable that you use galvanized nails or screws to fix the planks to
the posts, because the retaining wall is in contact with the wet or humid
ground constantly, therefore, normal nails or screws will rust easily.
You have bought some 75 mm and 100 mm galvanized nails to do
the job, so, you hope that you can drive these nails into the sleepers and
posts just by using a hammer, because it is the easiest and fastest way to get the job
done.
Okay, if you are good with your hammer and can drive nail
easily it is the best way to go, provided that the timber is soft enough to do
that, and if you have used treated pine sleeper it can be done, as all you need
to do now is to place the sleepers where you have marked on the posts and nail
them in, and then you can backfill behind the retaining wall and the job is
done.
But what about if you are using hardwood or old dry
hardwood, because you got it very cheap from a second hand timber yard, because
they were overstocked they sold this timber at a very special price, which was
less than half the price of the treated pine sleepers; so, you were happy to
buy it because it was cheap and the timber being hardwood lasts for a very long
time, but now you may have a problem to fix the sleepers to the posts, because
it is near impossible to drive nails into this old dry hardwood timber, unless
you drill a hole for every single nail, and even then the nails can bend even
if you are an expert with the hammer.
If this is the situation and it is hard to nail this timber
together, you can overcome the problem by using couch screws or bolts, so, you
use a drill and drill a hole for your galvanized couch screws or bolts and
tighten the screws or the bolt nuts with a spanner. But if you don’t want to do
this extra work and you want to use the galvanized nails that you have already
bought, then you can do the following: drill a hole as deep as you can just use
a bit a fraction smaller than the diameter of your nails, then try first with
the 75 mm nails how you go, if it works and you believe that the nail go deep
enough into the supporting post and hold well then your problem is solved, but
if the nail bends or don’t go deep enough then you can try the following, and this
is one of the last tricks of the old trade, which not many people know or use,
this trick is not a trick at all and once you know it, you can feel even stupid
for not thinking about it yourself; so what is it? Okay, when you pick up your
nail to nail in the hole you have drilled, dip the point of the nail a couple
of centimetres into a bit of Vaseline or mechanical grease, if this is not
available just wet a bar of soap and rub the point of the nail on the wet soap,
this greasing of the end of the nail will make it easier to drive it into any
wood including dry old hardwood.
I believe that I have said
enough about simple timber retaining walls, for you to have some idea how to
build them, so, now let us talk about another type of retaining wall that can
be easy to build, it is a type of concrete wall that the blocks are laid dry,
so, anyone can have a go; and if you don't get it right the first time it is
easy to fix.
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Link Block Mortar-less Walls.
Now let us talk about, Link Block Mortar-less Retaining Wall Blocks
This is a different type of retaining walls
made with dry blocks, the mortar is not required, it is a low wall easy to
build, so, most people can do it themselves. Now let me tell you this, on the
internet I have found this local supplier who has placed a few short videos how
to build these walls; the videos are at the bottom of the page, please use the
link here-under, I reckon it is worth to watch them, if you want to build any
retaining walls. As I have said this is only a local supplier in Brisbane
Australia, therefore, the same materials may not be available where you are
living, but by watching these videos you are going to learn something useful
anyhow.
No need for Mortar
So, I hope you have used the link above and
you have been able to see the videos. Anyhow, whatever you have learned can be
helpful one day.
And now let me continue to describe how to build a garden rock retaining wall.
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Building a garden rock retaining wall
To build a garden rock wall is a lot
harder than you think, and you need to know how to go about it, you see, you
need to have a good eye to see how the rocks that you have can fit together to
make a wall. There are a few ways how to do this depending how tall the wall is
going to be and lots of other things.
You see, if you have only a very low wall you can just lay
one single rock one after another, or two rocks one on top of another making
sure that you choose the best face to show at the top and at the front, the
other part of the rock can be hidden in the ground, or at the back since you
are backfilling behind the wall; in this case it is not necessary to use any
concrete, as the stones can be laid dry, but if you want you can use concrete.
Before you start the wall, you must dig all the grass and
loose soil, even if your wall is going to be low. If the wall is going to be in
a place where the ground is slopping down, make sure that you dig at least a
few inches into the solid natural ground, so that the wall you are building can
sit on firm natural ground, so, your wall is not going to slope down the first
heavy rain you have after building.
Now, in this example, we are building a low stone wall and
we are not going to use anything to bind the wall together, so, there is no
cement or anything else between the stones, in this case because there is
nothing to stop the rainwater to run between the stones you don’t need to worry
about drainage. You see, one of the greatest problems with retaining walls is
the water that can build behind them, the water and wet soil puts pressure on
the wall and if the water cannot get out the wall is going to fail.
Now it is helpful to have a look at some stone retaining
wall, and for this reason in mind I have found this link in the Internet; so,
have a look at the pictures in this link; www.australianrockwalls.com.au/ there are several types of stone
walls, now you can start thinking how and why they have been built that way.
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Deciding to build your own rock wall.
You needed more space, because you wanted to build a car
port, and put a trampoline for the kids. So, you have been digging in the
backyard, and finally you are satisfied that they can fit them in the space you
have made. But now you have this bank that stands almost vertical in the
backyard, it looks ugly, and you know that when the first heavy rain comes it
is going to start washing it down, and worse still it may collapse. So, you
think of building a retaining wall to hold the soil up.
For this reason, you have had a couple of quotes and had a
good talk to the contractors as you did not want to spend more money that was
strictly necessary, they did their best but still you cannot afford to pay the
full price, beside that you found that if you lay a dry stone wall, ether you
have to use stones that have been cut at the quarry and they cost a lot, or you
have to have a rock wall with a wider base and this is going to take away some
of the space you created when you dug, so really you need to think about it.
So, you have decided to build the stone retaining wall
yourself, what you have decided is that you are going to build an hybrid stone
wall, which you believe can do the job without costing too much; therefore, you
have looked for a rock supplier and ask for prices of the different materials
you may need, because you think that you can afford it, if you do the job
yourself.
By pure chance you have learned from the blokes that have
given you the prices, how many cubic meters of rocks you need and other things
that you were not sure before; well done sometimes in the building game things
work out this way, you learn a bit from here a bit from there and then you can
decide what to do with the information you have collected. There is nothing
wrong for doing this, unless you do it purposely to learn something, but if it
does not work out, then it is okay to use what you have learned from them.
I have to say that it has been done to me many times and
that I have done this myself; not only on quoting but also in buying something
new, if I have to buy something that I have never used before, I go to at least
three places and inquiry about it, by asking the right questions not only I
learn how much it is going to cost me, but I have learned how to use whatever I
was going to buy in the first place, of course, I end up buying from one of
them what I wanted to buy in the first place; sometimes I call this let me go
first to spy and then to buy, I know that some of these people are going to
feel a bit hurt, for using their time for nothing, but so what, sometimes you
win and sometimes you lose, as I have said it has been done to me as well and I
have felt a bit hurt, when I had to spend some time working out a price to
build something, and at the end I did not get the job, so, I spent all that
time for nothing, but that is life and we should accept the outcome whichever
way it goes. Anyhow, now let us go back to building the rock wall.
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Building the hybrid rock wall.
This hybrid wall that we are going to build is a big job, it
starts at the same level, as we have dug the ground approximately level, but
because we are building the wall only to the height of the natural ground
level, it is going to start from almost nothing and at the highest point will
be 1.8 meter, it is really two walls that meet and forms a square at the
highest point.
Here we must say that today some people think that this
should not be done, as this is neither a rock wall nor a concrete masonry wall,
as it mixes about everything, but so what, if it is convenient, why not do it?
I must say that in my life time I have built walls like this with whatever was
available on the site; and I mean everything in fact I was using stones that
were laying in this small creek bed and pieces of concrete that we had broken
to do some alterations and old bricks, some concrete and some mortar, this has
happened a few year ago and last time I have seen the owner he said that the
wall is still there. So, most things can be done if you know that it has got a
good chance to last a long time.
Let us go back to build our hybrid rock wall. Now, to build
this wall you need a few cubic meter of rocks, because you want the wall to
look as a rock wall, you don’t need very big rocks or special size rocks,
because you can use the cement wherever necessary to fill the gaps and this is
good, since the cement is less costly, you need a mixer, you need some gravel,
sand and cement; and of course, you must have the tools to do the job.
You got all this on site, and you can start to build. First
of all, drive a couple of pegs in the ground, exactly where you want the face
of the wall to be, tie and stretch a line on these pegs and see any adjustment
that you need to do before you start laying the first stone. What you are
looking for here is that the bank you are going to build the wall against has
been dug straight, it is almost vertical or a few degrees sloping, you have dug
a shallow foundation, because you want the wall to be strong and last for a
long time, so, you are satisfied that the foundation is going to be solid
enough, since it is well below the original natural ground, therefore, it can
hold a lot of weight and pressure, because the ground is very compact.
You have done all this, you have set the pegs again so that
your wall is set to be at least 10” thick overall, you have chosen this
thickness because most of the large rocks seem to be that thick, so now you are
ready to lay the first course of stones, mix a few batches of concrete and lay
it in the foundation and then before this concrete sets lay the first course of
stones on this concrete making sure that the bottom of the stones are below
ground level, so that the entire stone wall seems to start from below the
ground; once you have done that you can fill the back of the stone with
concrete a bit above ground level but below the full height of the stones,
because you want to leave enough room to lay next course of stone easily. Now
the wall is all set to go, but we need to reset how we must continue and
complete the hybrid rock wall, the right way with the right lean against the
bank. You need to lean the wall against the bank, so that the weight of your
wall by itself adds strength to the wall.
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Completing
the hybrid rock wall.
So, before we build this retaining wall, we must work out
how much lean against the bank we want, here we must keep in mind, how tall and
how thick is the wall, we don’t want the wall to lean too much and rely only on
the dirt behind it to hold it back, but at the same time we want to lean it
against the bank so that the weight of the wall is used to hold the dirt back.
Here we must go back to look at what happens if you lean a monolithic object to the point it is going to fall; what happens here is that the monolithic object is going to fall, only after its center of gravity falls outside the area of the base. Now we don’t want to go this far, and we don’t want to use the Centre of gravity to decide that, but we are going to lean the wall about two third of the thickness, so that the very top layer is still vertically one third of its thickness above the base; we believe that it is very safe to go this far and the wall would stand up even if we don’t backfill it. Anyhow, in our case we are not going to backfill it, because we have cut the bank exactly as the wall is going to be, you see we are going to use the bank as a template, so, we believe that we are not going to backfill much except at the top.
Now that we know how much we are going to lean the wall; we
are setting a leaning profile on every corner leaning approximately 10 to 12
centimeters per meter and we are ready to resume building our hybrid rock wall.
But there is still another important thing to work out; we need to make sure
that when it rains the water that seeps behind the wall can run out, so, we must
leave a way to drain this water out and at this level is the right place to do
that, so, we choose a few spots about a meter apart and mark them, then when
you lay next course of stones make sure that you leave a space between the
stones that the water can run out, you must also leave the back free of
abstractions for a course or two around this space, so, in this space after
laying the front stone, just lay some smaller stones dry against the bank to
stop the concrete blocking the drain, then you can resume to concrete the lot. Alternatively,
you can lay a few short pieces of pipe across the wall for drainage, but you
have still to make sure that they are clear of any obstruction at the back near
the bank.
So, now you can go back to mix some cement to lay your
stones, you can mix a batch of river sand four to one that you can lay between
the rocks to give them a bit of grip, you are laying the rocks in a straight
line that you have tied on the profiles, when you do that make sure that this
cement does not come too far forward, because you still want the rock wall to
look like a rock wall, at the same time do not forget that you have to leave
these spaces with no cement at all for the seepage where you have marked, after
you have used the batch of river sand and cement and laid say a course of
rocks, you can mix one or two batch of concrete to fill the back of the stones,
then you repeat this procedure until you build the entire wall.
At the top of the wall, because the wall in not going to be
level, you may have to do some adjustment to follow the height of the ground,
here you have to use common sense the best way you can, if you happen to have
enough wide and long rocks that can be used for a coping, use them to finish
your wall, if not, just use your common sense and use anything that is
available, even if it is going to be a strip of concrete in the back of the
wall, so that all the wall is tied up.
I hope I have explained well enough for you to follow my way
of building this hybrid rock wall. Here I want to add that this is just one way
out of several other ways that can be used. A lot depends how the bank has been
cut and if it follows very closely the shape of the wall, so, you can use it as
if it is formwork, but if there is going to be some back filling to be done,
you may have to consider some temporary formwork that can be easily removed
before you backfill. All these things can vary from job to job, and if you see
that it is hard to build your hybrid rock wall, then you must consider other
ways to build your retaining wall.
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Why we need these retaining walls?
When the block of land is steep, it requires a lot of work
to be done, if you want a small portion of your land flat, so that you can
stand and enjoy whatever is there to enjoy and do whatever you want to do in
the open air. See the photo here under,
they have built a Besser block retaining wall with an indent in it, mainly to
give extra strength to the block wall and to put this concrete slab and use
this indent with whatever they want to do next. (This photo is only available in the original article) Note that above this block wall
there is another sleeper retaining wall, these sorts of things are very costly,
and we must plan it out before we start, anyhow, under below we are going to
write about a Besser block retaining wall, first just a normal strong retaining
wall and after that we are going to build a leaning Besser block wall, similar
to the hybrid rock wall.
Building a Besser block retaining wall.
Besser blocks retaining walls require a reinforced concrete
foundation with steel starter bars placed exactly in the centre of the hollow
part of the block, when you look at the wall from the front or back, and if possible,
a bit close to the side where the pressure of the soil is going to be, but that
can be asking too much from the concrete man and the steel fixers. So, a
profile must be in place before you can even concrete the foundations, or fix
the steel in the foundation, because all measurements need be known and easily
measured while working on it.
This is a very demanding job and it is not a do it yourself
job. So, the name that I have given this article DIY retaining wall would not
apply in this case, you see I apologise because I was forced to use DIY just to
overcome the problem of the title that happens when we start a new article and
find that the name we have chosen has already been taken.
Anyhow, when you start laying the first Besser block in most
cases, it is helpful if you can start the first course with an open block, this
block looks like a square C, and you lay it with the open side facing
away from the bank that it is going to hold back when everything is done, the
corners are built with normal blocks and most of the walls are built with
blocks that look like an H, so, it is easier to fill up with concrete,
once the wall has been built. Now while the block layer is laying the blocks, he
will have to lay horizontal steel bars between the courses of blocks as
specified, if there is a plan and specifications, or use common sense, or copy
from the specifications of a similar job he has done, the vertical steel bar
will be inserted from the top before or while pouring concrete into the blocks.
Now the reason why we need to use an open C shaped
block for the first course, it is because it is necessary that before we fill
up the blocks we remove the mortar that has fallen down at the bottom of the
blocks while we were laying them, you see, we want a solid base and we want the
concrete to bind around the starter steel bars that we have laid in the
foundation and this is the best way to make the retaining wall as strong as we
can. Once that is done, we can fix a plank against the openings, and we are
ready to pour the concrete in the wall.
Here we must say that for this retaining wall we have not
mentioned any drainage yet, so, what happen to the water that seeps behind the
wall needs to be worked out, you see, sometimes when we build walls this strong,
there could be a reason that we do not want any water past the wall, it can be
part of a base of a house being built, so, we have not even left any weep holes
in the wall, because there is going to be a drainage pipe laid behind the wall
surrounded by gravel. The wall might also be treated with special paints to waterproof
it.
This is one type of blocks retaining wall, and I am going to
write about another type, where we lean the retaining walls towards the bank for
future back fill that it is going to hold up, this is a large job that we did
years ago in a yard of a new large home in Redhill a Brisbane suburb. We are
going to write it here, to show you another type of retaining wall and the many
ways that can be built.
Redhill backyard problem solved.
Years ago, we worked on this part brick house in Redhill, we
say part brick house because the top floor of the house and the interior was
made of timber, so, it was a brick veneer, the base was solid bricks and
blocks, it was a large house, on a large block of land had two street frontages.
It was on a hill and the difference between the front and the back yard was a
lot, but the two street frontages was good, because the house was being built
on the higher part of the block of land, where it was nearly flat there and
almost level with the road, so, there were no problem building the house; but
the back yard was very steep, in some places could have been up to 45 degrees.
So, when we finished the brickwork on the house we were
asked from the owner, if we could build some retaining walls, because the
backyard was useless as it was. So, after discussing the financial part how he
would pay us; we discussed how we could fix the back-yard building block
retaining walls. So, it was agreed that we had to lay these block retaining
walls leaning a few degrees towards the bank. We had to build concrete stairs
on one side, so that the house could also be entered from the back street, so,
working together with the owner we did the following.
Because you cannot build a very high wall on the road
boundary, first a section of about 4 feet wide (1.2 m) was dug and a foundation
was poured, with starter steel bars as needed and the main wall was set about a
meter from the road where the first retaining wall was to be build, this was
the main foundation for a start, some of the small foundations and other
adjustment we had to work out as the work progressed.
The decision was that we had to build the wall leaning
towards the bank for extra strength; you see, when building retaining walls the
weight of the retaining wall with the weight of the foundation must be more
than the weight that the backfill can move, if possible that you can build a
very strong monolithic wall and foundation together this is the best solution,
in this case it was not possible, because the job was too big, beside that you
need to have a very wide and heavy foundation and a very strong bond between
the foundation and the wall, since this bond between the foundation and the
wall is the weakest point unless it is concrete and poured together, but we
were using blocks to build the wall, therefore, it had this weakness at the
bottom of the wall, therefore, by leaning the wall towards the bank, the weight
of the wall becomes the first point or
resistance.
Now, how much we must lean the wall was left to us block
layers, because for sure there will be problems, and there were several
problems to overcome; the first problem is that if you have to return the
corners it cannot be done, but we had corners on the boundaries of the joining
block of land, so, we had to think how to overcome this drawback, for this it
was decided that we would not build the corners as usual, we should treat them
as separate, but we would place a corner steel rod every course, instead of
every second course, as in the wall itself.
There was also the possibly that while we were building the
wall, if we lean it too much it could fall on the inside, while we were
building it, so, we had to strike a balance. Knowing that this first wall was
going to be no more than 3 meters high, we worked out that if we lean the wall
5 centimeters per meter, the top of the wall was going to be about 15 centimeters back from the perpendicular, the blocks were 19 centimetre wide and it would be
okay, as once the wall was built it could stay up on its own without falling
inside, but while we were building we should be very careful not to apply any
extra weight on the leaning wall, just for fear that this could happen we added
a couple of block piers behind the wall, this would not only make the wall safe
for us while we were building it, but it also would make the whole wall
stronger.
Anyhow, we built this block wall placed the reinforcing rods
in place, we also built some concrete steps on one side of it, so, that if you
happened to be on the back road you could walk to the house, the ready-mix
truck came, and the wall was filled with concrete and that was the first stage
finished. We had to wait for this wall to become strong before we could
backfill it, and then we could build another retaining wall halfway the
backyard to finish the job.
Dear readers, be warned that this type of work can only done
from very experienced block layers, as it breaks all the rules in the building
trade, but we did it and it worked.
Anyhow, this article is becoming too long, so, see you in our next article, Mix your own cement.
