My other sites; http://frankmenchise.com,http://diybrickwork.com,http://manneedsgod.co.uk
Anyhow, you can also see more at this addresses, DIY brickwork
and, http://diybrickwork.com, To see more, DIY 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 also to put this concrete slab and
use this indent with whatever they want to do next. 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 starts, anyhow, under below we are
going to write about a Besser block retaining walls, 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 unless you are a tradesman. 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 frontage. 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 centimetre per meter, the top of the wall was going to be about 15 centimetre
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
back-fill 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.
This is the last part of this article about retaining walls. So next blog we will be talking about, Mix you own cement, for sure you can learn something useful in this article.
See you soon.
No comments:
Post a Comment