Dry Stack Limestone Garden Wall. Lebanon PA.
On this stone masonry project we have a a dry stack stone wall with a concrete cap. This wall is located in the parking lot of a popular resturant in Campbelltown / Palmyra Lebanon county. The stone for this wall were recycled from a building that was partially taken down. It is ideal when you have the option to reuse stone that were sourced on site. It saves on cost and ensures that there will be a perfect color match with the other exhisting walls. It can be a challenge if not impossible to match exhisting walls when the materials used in those walls have been exposed to the elements for many years. The sun and the weather change the color of materials over time.
Your typical dry stack stone wall is usually built right on top of the ground with very little excavation if any. They are usually not very tall and wide, making a sturdy base. The empty space inside the wall is then filled with crushed stone, this is also know as back fill. The advantage to building a wall this way is cost. There isn’t a trench that need to be dug or a footer that needs to be poured. Then you don’t need to lay block to get up to grade where you start the stone wall. All of these things add time and material cost to the price of the wall making it more expensive. However that extra cost means you wall will stay where it was built.
The disadvantge to doing a typical dry stack stone wall is they move. Since a dry stack stone wall is built on top of the ground when the ground freezes it will lift the wall. Then when it thaws it will settle back down. This does not happen evenly. So over time with many freese thaw cycles stone can work themselfs out of place and sections of wall can sink. Now how the wall was built can affect how long it takes for this to happen, but inevitably the wall will move. Unless you happen to live in an area where the ground does not freeze. Here in the north east that is not the case.
There is however a compromise. A way of building a dry stack wall that gives you extended durabulity while still saving on cost. This is where we get into how this wall was built. Your typical dry stack stone wall is built on top of the ground. A trench has been dug for this wall. However it is not nearly as deep as it would be if you were going to pour a footer. It is a foot or two at most. Beneth the ground this wall is wider than the wall that is above the ground. Giving it a sturdy base. The main difference between this wall and a typical dry stack stone wall is the back fill. Rather than using crushed stone this wall has been backfilled with a Portland cement grout. Using a Portland cement grout for back fill does two things. First it fills the wall solid, meaning there are no voilds or areas that the wall can settle into. Second it will surround the stone and work its way inbetween grabbing ahold of them and keeping them in place. Also the concrete caps are layed in mortar on top of this wall. If this wall did not have solid back fill the mortar joint around the cap would crack within a year or two. Due to the fact that the wall is moving so much. This is not a perfect soulution like a wall on a footer is. However it will add many more years of maintenance free life to a dry stack wall. Also cutting down on the cost.
