DIY Retaining walls
Welcome to our page 15, DIY Retaining walls
Let us talk about retaining walls. Most people that own a house, always would like to enjoy to improve their property by doing a few things in the yard, where they can stay outside and have a garden, or perhaps have a barbecue with their family and friends, but there are times when it is not easy to do, because the yard is not level and in some places it is hard even to stand up straight, so it is time to think of something about how to improve the situation, perhaps a retaining wall might help, so how do we go about, how to build a retaining wall one may ask?
Before we answer that question, let us talk about the retaining stone wall shown here in this hub, I reckon that it is a very well built stone wall, here we need to say that we all would like to be able to build ourselves a wall like that, or get some professional to build a stone retaining wall like the one shown here at the beginning of this hub, if we need one, but a wall like that is very costly and also 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 should 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 perhaps 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 go back and try to write about some do it yourself retaining walls, as there are many easy and also hard retaining walls to build, as there are many reasons for building them.
How to build a retaining wall
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 of all we have to 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 us, in other words we have to study the situation first, so that we can decide what type of retaining wall to build. Now here we need to say also that we should try to build our retaining walls with those building materials that are easily available, to avoid extra cost. In other words look first where you are and what local materials are available. You see, if you are in a place where stones or rocks are plentiful, and you might even have some of these in your yard, then it could be a lot cheaper to build your retaining wall with these materials, and even if you have to buy the lot they would be cheap anyhow; but if you are in a place where there are plenty of trees and there is even a sawmill nearby, then it would be more appropriate to build it with timber.
Having said that it is obvious that for you to decide what is the best retaining wall or walls to build we need to show and explain to you what could be done and how could it be done. Now this article is being written for this very purpose in mind, therefore here under we will try to do just that. Let us start with a very easy and cheap retaining wall that most people would be able to do it themselves, even if they do not know much about building anything, as long as they have a few tools and know a little bit how to use them; here we suggest that anyone of us is able to dig a few holes in the ground to place a few short posts and place a couple of sleeper timber planks against those posts and secure them by nailing or screwing them to the posts. It sound and is very simple, isn’t it? But this is not the only retaining wall that we would like to show you so keep reading this article as we add more and more to it, as it could become interesting and you could even learn something about building them.
Timber sleeper retaining walls
Building a low timber sleeper retaining wall is very easy, just about everybody would be able to 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 sleeper that today are easily available at most timber yards.
Here are a couple of addresses of local timber merchants and hardware to get what you want, just for everybody to check them out; you need to find your own, if you live somewhere else.
Now, you have visited your local supply and you have got all you need and 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.
Posts can be made from the same material of the sleepers; you just have to saw them to the right length and fix them in the ground as we have said above. Just to make it easy let us say for the time being that your wall is going to be just 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 would be better if you work it out from the top down, because it is easier to change the bottom than to 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 sleeper 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 as long as possible 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 and 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 to be able to drive these nail into the sleepers and posts just by using a hammer, because you have not got a drill, and even if you have you think that nailing them is the 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 really cheap and the timber being hardwood would last for a very long time, but now you might 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 might 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 could be able to 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 could do the following: drill a hole as deep as you can just use a bit a fraction smaller then 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 could 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 centimetre 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 could 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.
Link Block Mortarless Walls
Link Block Mortarless Retaining Wall Blocks
This is a different type of a retaining wall made with dry blocks, as the mortar is not required, it is a low wall easy to build, and so most people would be able to do it themselves. Now let me tell you this, on the internet I have found this local supplier who has also placed a few short videos how to build these walls, at the bottom of the page, if you use the link here-under, so I reckon it is worth to watch them if you want to build any retaining walls in the future. As I have said this is only a local supplier in Brisbane Australia, therefore the same materials may or may not be available where you happen to be 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 could be helpful one day.
And now I would like to explain a certain situation that I have come across while I was writing this hub.
Let me explain the situation.
Dear readers this article was supposed to be just about retaining walls, but as it happens I was forced to change that name because it was already taken in Hub Pages, so do not aspect that all the retaining walls described here are suitable to do it yourself, just because we have named our hub, DIY Retaining walls, because a lot of the retaining walls that we are going to describe here are not going to be easy to build, so they are usually jobs for trades people, but if you feel that you can do the job then have a go at it, sometimes a bit of challenge is good for you. Now that we have explained the situation let me continue to describe how to build retaining walls, so let me describe how to build a garden rock wall.
Building a garden rock retaining wall
To build a garden rock wall as shown in the picture here is a lot harder than you think, and you need to know how to go about it, you see for a start 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 ether 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 as well.
To start with 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 deep enough and reach solid natural ground at least, so that the wall you are building can sit a couple of inches or a lot more than that into this firm ground, So that your wall is not going to slope down the first heavy rain you have after building it.
As we said in this case we are only 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 rain water 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 could be 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.
Deciding to build your own rock wall
You have been doing some works in the backyard as you needed more space, you wanted to build a car port and also put a trampoline for the kids. You have done the digging and are satisfied that everything is going to fit easily; 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, perhaps a stone rock wall would be good to hold the soil up.
For this reason you have had a couple of quote for this job 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 would do the job without costing too much and also it would not take too much space; therefore, you have already looked for a rock supplier and ask for prices of the different materials you might 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 might need and another few things that you were not so 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 as long as you do not do it purposely, 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 also 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 a rock wall.
Building the hybrid rock wall
This hybrid wall that we are going to build is really 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 have to say that today some people might think that this cannot or 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 have to 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 as long as you know that it has got a good chance to last a long time.
Let us go back to build our hybrid rock wall, first of all 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 might be good, as the rocks could be less expansive, you need a mixer, you need some gravel, sand and cement; and of course you should 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 wand 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 just a few degrees sloping, you have also dug a shallow foundation as you want the wall to be strong enough to 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, and therefore can hold a lot of weight and pressure, even though you have dug it out one side, the ground is very compact.
You have done all that you have set the pegs again so that your wall is set to be about 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 have to 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.
Completing the hybrid rock wall
What we need to do now: first of all we are going to set up how much lean against the bank we want, before we build this retaining wall, here we have to keep in mind a few things before we definitely decide that; first of all we have to consider 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 one has to go back to look at what happens if you leans a certain 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 centre 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 for a few reasons, 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 only 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 anything, 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 it at all.
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 centimetres per metre and we are ready to resume building our hybrid rock wall. But there is still another important thing to work out; you see we need to make sure that when it rains the water that seeps behind the wall can run out, so we have to 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 also have to leave the back free of any 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 could 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 just common sense the best way you can finish, 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 would like 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 that 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 this things can vary from job to job, and if you see that it would be hard to build your hybrid rock wall, then you have to consider other ways to build your retaining wall.
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 would like to do in the open air. See the photo here under, they have built a besser 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 one should really plan it out before one starts, 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, somehow similar to the hybrid rock wall.
Besser block retaining wall
Besser blocks retaining walls require a reinforced concrete foundation with steel starter bars placed exactly if possible 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 could be asking too much from the concrete man and the steel fixers. So for a start a proper profile should 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 really a do it yourself job that is easy to do. So the name that I have given this hub 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 hub and find that the name we have chosen has already been taken.
When you start laying the first besser block in most cases, it could be helpful if you could 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 would be built with normal blocks and most of the walls are built with blocks that look like an H, so that 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 some horizontal steel bars between the courses of blocks as specified, if there is a real plan and specifications, or just 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 we need to use an open C shaped block the first course becomes obvious now, 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 really want a very 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 have to mention 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 usually there could be a reason that we do not want any water past the wall, perhaps it is 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 some special paints to water proof it.
This is just one type of blocks retaining wall and I am going to write about another type, where we lean the retaining walls towards the bank or 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, just to show you another type of retaining wall and the many ways that can be built.
Redhill backyard problem
Years ago we worked on this part brick house in Redhill, we say part brick house because the top floor interior was made of timber and was a brick veneer, the base was solid bricks and blocks, it was a large house and the 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 and was nearly flat there and almost level with the road, so there were no problem there, but the back yard was very steep, in some places could have been up to 45 degrees. 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 started to discuss how we could fix the back yard building block retaining walls, and so it was agreed that we had to lay these block retaining wall leaning a few degrees towards the bank and there was going to be concrete stairs on one side, so that the back could also be entered from the back street and so working together with the owner we did the following.
Because you cannot build a very high wall on the road boundary, first of all 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 together with the weight of the foundation should be more than the weight that the backfill could move, if it is possible that you could build a very strong monolithic wall and foundation together this could be the best solution, in this case it could never be possible, because the job was too big, beside that you need to have a very wide and heavy foundation and also 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, so by leaning the wall towards the bank, the weight of the wall would be the first point or resistance.
Now, how much we should lean the wall was left to us block layers, because we for sure would have some problems, and there were several problems to overcome here; the very first problem is that if you have to return the corners it cannot be done, of course we had corners on the boundaries of the joining block of land, so we had to think how to overcome this drawback first of all, for this it was decided that we should not build a return corner 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 it, 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 would be able to go 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 built another retaining wall half way 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.