Stone retaining wall contractor, RL Sanborn Masonry, is a
located in Portland Maine and provides professional stone
retaining wall construction, restoration and repair services
throughout Cumberland County Maine.
Many material options exist for stone retaining walls and are provided by
local stone suppliers.
You may choose from variations of stone, brick, concrete block or
poured concrete. Stone retaining walls may be set with mortar or dry laid
depending on preference.
reinforced with steel and installed below the frost line, to prevent shifting
Would you like a free retaining wall consultation and free retaining wall
estimate? (click here) or Call (207)619-7473
What is a retaining wall?
A retaining wall Is a structure that holds back soil or rock from a building, structure or area. Retaining walls prevent downslope movement or erosion and provide support For
vertical or near-vertical grade changes.
Cofferdams and bulkheads,
structures that hold back water, are sometimes also considered retaining walls.
Retaining walls are generally made of masonry, stone, brick, concrete, vinyl, steel or timber. Once popular as an inexpensive retaining material, railroad ties have fallen out of
favor due to environmental concerns.
Segmental retaining walls have gained favor over poured-in-place concrete walls or treated-timber walls. They are more economical, easier to install and more
The most important consideration in proper design and installation of retaining walls is that the retained material is attempting to move forward and downslope due to gravity.
This creates lateral earth pressure behind the wall which depends on the angle of internal friction (phi) and the cohesive strength of the retained material, as well as the
direction and magnitude of movement the retaining structure undergoes.
Lateral earth pressures are typically smallest at the top of the wall and increase toward the bottom. Earth pressures will push the wall forward or overturn it if not properly
addressed. Also, any groundwater behind the wall that is not dissipated by a drainage system causes an additional horizontal hydrostatic pressure on the wall.
As an example, the International Building Code requires retaining walls to be designed to ensure stability against overturning, sliding, excessive foundation pressure and
water uplift; and that they be designed For a safety factor of 1.5 against lateral sliding and overturning
Gravity walls depend on the weight of their mass
(stone, concrete or other heavy material) to resist
pressures from behind and will often have a slight
'batter' setback, to improve stability by leaning back
into the retained soil. For short landscaping walls, they
are often made from mortar less stone or segmental
concrete units (masonry units). Dry-stacked gravity
walls are somewhat flexible and do not require a rigid
footing in frost areas.
Earlier in the 20th century, taller retaining walls were
often gravity walls made from large masses of concrete
or stone. Today, taller retaining walls are increasingly
built as composite gravity walls such as: ego synthetic
or with pre cast facing; gabions (stacked steel wire
baskets filled with rocks); crib walls (cells built up log
cabin style from pre cast concrete or timber and filled
with soil); or soil-nailed walls (soil reinforced in place
with steel and concrete rods).
Prior to the introduction of modern reinforced-
soil gravity walls, cantilevered walls were the
most common type of taller retaining wall.
Cantilevered walls are made from a relatively
thin stem of steel-reinforced, cast-in-place
concrete or mortared masonry (often in the
shape of an inverted T). These walls cantilever
loads (like a beam) to a large, structural
footing, converting horizontal pressures from
behind the wall to vertical pressures on the
ground below. Sometimes cantilevered walls
are buttressed on the front, or include a
counter fort on the back, to improve their
stability against high loads. Buttresses are
short wing walls at right angles to the main
trend of the wall. These walls require rigid
concrete footings below seasonal frost depth.
This type of wall uses much less material than
a traditional gravity wall.
See also: Tieback (geo
This version of wall uses cables
or other stays anchored in the
rock or soil behind it. Usually
driven into the material with
boring, anchors are then
expanded at the end of the
cable, either by mechanical
means or often by injecting
pressurized concrete, which
expands to form a bulb in the
soil. Technically complex, this
method is very useful where
high loads are expected, or
where the wall itself has to be
slender and would otherwise be
Types Of Retaining Walls
What is masonry?
Masonry is the building
of structures from
individual units laid in
and bound together by
mortar. The common
materials of masonry
construction are brick,
stone such as marble,
block, glass block, and
tile. Masonry is
generally a highly
durable form of
the materials used, the
quality of the mortar and
workmanship, and the
pattern the units are put
in can strongly affect the
durability of the overall
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