The face stones visible edges should rest only on stone not mortar so scrape away any mortar that squeezes out.
Natural stone retaining wall with mortar.
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.
Dig a trench about 6 inches wider than your wall.
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.
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.
It must be deeper than the frost line or at least 12 inches deep for a 3 foot high wall.
Remove the stone spread a trowelful of mortar on the wall and tamp the stone into it with a mallet.
Anything taller should be handled by professionals.
This is also ideal for stone columns.
A mortar wall must be built on a firm foundation or its joints will crack.
Tamp the gravel in the bottom of the trench and pour at least 8 inches of concrete.
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.
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.
This is high strength contractor grade and pre blended mortar.
For projects that don t require a lot of mortar use smaller bags of mortar mix or concrete.