On Apr 21, 8:40*am, Ernie Willson wrote:
MiamiCuse wrote:
In our circular driveway we have a border around a 20' tall Queens Crepe
Myrtle tree made of a few 4x4 landscape lumber tied together with metal
angles. *We are going to change that to using retaining wall bricks.

One question is the wall would be a foot higher than the current height of
the 4x4s. *I am thinking may be I need to fill in some soils inside the ring
to bring that up 6 inches or so. *Would doing so hurt the tree in any way,
adding 6 inches of soil and another 2" of much at it's base?

I am going about 4 bricks tall, each brick 8 inches tall. *The guy I was
talking to that may help me install this says there is no need to use mortar
in between each brick all we need to do is to have some sand base and stack
them up. *Is that the case?

Thanks,

MC

ISTM that you should not change the soil depth around the trunk of the
tree. I would recommend that you leave a circular area around the base
of the tree where the soil level is not raised. This circle should be
about 6 to 8 ft in diameter and lined with the same masonry as you use
for the retaining wall. In other words the tree would look like it is
planted in a shallow hole. You see this technique employed often where
it becomes necessary to raise the ground level around existing trees.

If you cover the area from the interior wall to the outer retaining wall
(with bricks etc.) then you are denying the tree necessary rainwater. I
would not cover this with brick.

Whether or not you can just place your retaining wall on sand on grade
depends on your frost line. If you live in a relatively cold climate (
say New York and North) then you should start your footings below the
frost line or frost heaves will knock the wall over after a few years.

I would recommend mortar, but this may not be necessary.

HTH,

EJ in NJ

Thanks. However, there is not as much space as you think. The entire
soiled area around the semi-circular driveway is about 18' at the
widest spot, that would be like the diameter except it is actually
less than half a circle. I will be replacing the wood border with a
brick border. If adding more soil is a bad idea I will just leave the
soil at the current level, and not stack the wall as high as
originally intended.

My location is Miami, FL, so no frost to speak of, but does have
frequent rain and occasionally hurricane force rain in the summer
months.

MC