It must be deeper than the frost line or at least 12 inches deep for a 3 foot high wall.
Natural stone retaining wall with mortar.
Anything taller should be handled by professionals.
Although type s mortar must have a minimum compressive strength of 1 800 psi it is often mixed for strengths between 2 300 and 3 000 psi.
A mortar wall must be built on a firm foundation or its joints will crack.
The easiest way to build a stone retaining wall is to use the dry stack method that requires no mortar between stones and does not need a concrete footing like mortared walls do.
Building a retaining wall is suitable for diyers as long as the wall is a maximum of 3 feet tall in most areas.
Natural stone is often laid in a dry stack style without any mortar but mortar stabilizes the stones to keep them from falling off the wall.
For projects that don t require a lot of mortar use smaller bags of mortar mix or concrete.
This is high strength contractor grade and pre blended mortar.
Mortar is not always necessary but it is especially.
Dry fit each stone first to see that the vertical joints are staggered and the outside faces just touch the line.
Type s is the common choice for many below grade applications such as masonry foundations manholes retaining walls and sewers as well as at grade projects like brick patios and walkways.
If you re building a retaining wall use a blended mason mix which includes the heavy duty mortar type s masonry cement and graded sand.
Remove the stone spread a trowelful of mortar on the wall and tamp the stone into it with a mallet.
Dig a trench about 6 inches wider than your wall.