I have fence company installing a retaining wall 2' tall and a fence. They have done retaining walls before and seem to know what they are doing, but they are setting the prefab stones at ground level (they flattened and leveled even with sidewalk) with crushed rock on top rather than dig down 3" + gravel as per the instructions of mutualmaterial.com states for manorstones. When questioned, owner said they will put dirt in front (wall inset from sidewalk a foot).
They just finished first day and got ground level and just started putting blocks in. Quick recommendation/help appreciated.
A true retaining wall -- engineered to hold back a slope -- has a below-ground concrete footing wider than the wall. The depth of the footing is proportional to the height of the wall. The wall itself needs steel rods that extend into the footing (placed before the footing concrete is poured), surrounded within the wall's vertical channels with more concrete. Where appreciable force from the slope is expected, horizontal steel rods within the footings and the wall itself might also be required. This use of steel and concrete is dictated by the force of the slope behind the wall, and not by the wall's height; that is, even a low retaining wall requires this.
Perhaps you are getting a slough wall, which does not support a slope. A slough wall merely prevents loose dirt and other material
-- slough (pronounced "sluff") -- from trickling or eroding down the slope. I have a slough wall at the base of the hill in my back yard. The toe of the slope is at the bottom of the wall, not near the top. The slope was engineered (benched and compacted) so that no retaining wall would be needed.
David Ross in news: snipped-for-privacy@nowhere.not:
yeah. sounds like bs. even if not a true retaining wall, i think it needs to extend below grade to firm earth (under the base rock), else will sink irregularly.
some more web info:
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nice. :-)
-- In any case, it is sufficiently steep that I only climb it when truly necessary. Several times, I have fallen on it, wrenching various parts of my anatomy. Once I actually fell off it, tumbling over the slough wall at the bottom.
ow. maybe a mass of shrubs are needed to catch hurtling bodies. :-)
-- When the rain fell, it ran right through the cracks and lubricated the boundary between the surface and subsoil. The surface (partially pulled by iceplant that suddenly became waterlogged) slid down the slope, failing to a depth of about two feet. Thus, everything on My Hill was planted since the spring of 1993, when the repairs were completed (at a cost almost equal to what I paid for my house approximately 20 years earlier). Although the plants on My Hill are somewhat drought-tolerant, I now keep the soil moist; I water My Hill heavily every other week, allowing only the top few inches to dry.
it sounds like maybe there could also be an unmixed boundary between soil types.
I would say that it all depends on where you live. If you are in a warm climate without any problems with frost heaving, then it probably won't be a problem. If you are in a cold climate, you may find that the wall will shift after several freeze thaw cycles. In any event, I would expect the materials to be used as specified by the manufacturer. I have an Allen Block wall that was constructed on a 12 inch bed of crushed, compacted stone with geo-grid placed between every two courses. There is no poured footer or steel rods and it seems quite stable. In my opinion it is a retaining wall but I won't argue with an engineer over the definition.
Well, a REAL retaining was is not much different from a dam, except that it is holding back earth, and during rains,may also be holding back water. All of which which is exerting force in a horizontal direction. That is, if the wall holds. it is an engineering issue. Don't you need approved drawings, plans, from some local building department? You seem to have no below-grade footings!
In some jurisdictions, a 2' retaining wall requires a permit, which means plans drawn by a professional engineer. At the same time, a
5' slough wall requires no permit.
The difference is that a RETAINING wall must indeed retain the slope against which it is built while a slough wall is a free-standing wall against which LOOSE dirt might accumulate AFTER construction. The permit process might involve inspections by both the government agency that issues the permit and the engineer who drew the plans. The purpose is NOT bureaucracy for its own sake; the purpose is to ensure that the wall is built safely (e.g., that it will not fail and dump a mudslide into someone's home).
As I tried to indicate earlier in this thread, if the person starting the thread is not really trying to support the slope, then he does not need a retaining wall. Instead, he might merely need a slough wall.
The wall is indeed intended retain the dirt behind it. Actually, the area is 8' wide. At one end it is just over 2' tall, comes out 2 feet or so, then slopes down to bottom. We put in the wall, which mean digging into the hill/slope. The wall was constructed of manorstone (60lb blocks), 2' high. It had crushed rock (2-3") underneath and backfilled with same rock. Now completed, the ground is near flat behind it. We set the fence 5 inch back from the inner edge of wall, which was RIGHT where the electrical lines ran...didn't want to take a chance. All in all, looks great. (still would have been happier if first layer had been partially burried though).
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