Support and Retaining Walls

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SUPPORT WALLS FOR YOUR WATERFALL: #3 CONCRETE BLOCK WALL

September 16, 2008 in , Building a Waterfall - Important Details, Support and Retaining Walls by Ben | Permalink

Our next example of a support wall on your water feature is a concrete block wall.  These walls are the strongest and will last the longest.  A properly built block wall should last decades.   These walls can be faced with natural rock for a more natural look and are stronger than stacked rock.  When building a waterfall wall, stability is important.

The first step to your block wall is to dig out a footing for the wall to sit on.  This footing should be twice as wide as the wall, and extend 12″ on the ends.  This is called a T foundation because it forms an upside down T.  After you dig down 7″, you will want to tamp down 2″ of base rock, then set in one level of blocks on top of the base rocks.  You will want to then drive 1/2″ rebar vertically down through the holes in the blocks and into the ground.  You will want to tamp them down to the appropriate height of the proposed wal.  Next take the blocks up and off the rebar,  then lay in 2 lateral pieces of 1/2″ rebar.  These rebar pieces should be raised off the ground 3″ with rock or a “Dobey”. The next step is to pour 5″ of concrete level.  It is important to have leveled wood boards bordering the footing to ensure a leveled surface to smooth the concrete on.  Smooth the concrete around the vertical pieces of rebar, and let set for one day.

The next day you can start to set the blocks up and over the vertical rebar, and stack leveled on top of each other.  It is better to pour the concrete into each block as you build up.  As you get to the top of the waterfall wall, smooth out the concrete and you are done with the wall.

After this wall is built it is important to have drainage.  Slowly fill the area next to the wall  with 6? wide of drain rock, all the way to the top. As you move in the drain rock tamp down  soil next to it all the way up to the desired height. It is also a good idea to create a landscape fabric barrier between the rock and the soil, this will ensure better drainage. After you have tamped down the soil for the waterfall, you are ready to build your water feature.

SUPPORT WALLS FOR YOUR WATERFALL #2: PRESSURE TREATED WOOD

August 23, 2008 in , Building a Waterfall - Important Details, Support and Retaining Walls by Ben | Permalink

Another example of an inexpensive wall to support your waterfall is a pressure treated wood wall. The pressure treated wood will last longer than other lumber, and is a better alternative than the dwindling supply of redwood trees. When using pressure treated wood, it is important to wear gloves when handling, and proper ventilation masks and eye protection when cutting the material. Pressure treated wood is treated with chemicals to prevent decay, should not be inhaled, and hands should be washed.

A good support wall should have 4×4 posts set in a hole at least 18″ deep. Each post should be set no further than 4′ apart and each post should have 2 pieces of rebar driven down in the hole, and filled with concrete. Make sure the posts are level in all directions, and leave the posts to dry for at least one day. It is important to measure the posts properly to fit the desired length and width as well as the length of wood used. For instance, if you are using 8′ long pieces of lumber, make each post 4′ on center from each other. This will insure no wasted wood, and less labor and cuts.

After the posts are set its time to screw in the wood. Each piece of wood should be screwed into the post facing the front (waterfall side). The size of lumber that you use is really up to you, but I would recommend utilizing a 2x12x8′. This length is easy to use and makes for simple measuring.

After the wood is screwed into the posts it is important to attach landscape fabric to the wood that will be touching the soil, this will allow the wall to last even longer. Drainage is also an important factor in building these walls. Even though the support walls used for waterfalls will not be holding much weight, it is still important to have drainage.  Slowly fill the area next to the landscape fabric with 6″ wide of drain rock, all the way to the top. As you move in the drain rock tamp down the soil next to it all the way up to the desired height. After you have tamped down the soil for the waterfall, you are ready to build your water feature.

SUPPORT WALLS FOR YOUR WATERFALL: DRY STACKED ROCK WALL

August 9, 2008 in Building a Waterfall - Important Details, Support and Retaining Walls by Ben | Permalink

There are many different walls that you can build to support the soil of the waterfall.  The cheapest and easiest wall will be the “Dry Stacked Rock Wall”.  These walls have been built as far back as the roman times, and still stand today.  These walls consist of natural rock that are set in the soil, and built up on top of each stone.  It is important to utilize a rock that is more squared or angular, than a smooth rock, for they will stack easier.  The bottom rock is your foundation rock, and should be the biggest, as well as the most leveled rock.  From there each rock should be tamped into place with a rubber mallet until each rock is set.  Then back fill with soil as you go, until you reach the top.

This type of rock wall will be totally stable up to 3′ tall, after that height the constitution of the wall is weaker.  These rock walls are successful due to the natural drainage it provides.  Each rock space will drain the water from the ground above.  Most walls fail due to build up of water behind the wall, which in turn blows the wall out.

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