digest
Short Summary
Main recommendation: For a fence post in clay soil that holds water, skip gravel in the hole, set the post level using a string line, and use a quick-setting concrete mixed with about 2.8 liters of water per bag, adding extra clay and tamping it down on top. The speakers explain that because this ground freezes, the standard two-bag, 48-inch installation printed on the bag does not apply, so they use one bag and dig the hole about 4 feet 6 inches deep.
Key Points
- Gravel is not useful in water-holding clay: it raises the post's setting depth without draining water and simply becomes a pool.
- Use a long level and a string line at the top and bottom of the fence height so only the two end posts need precise leveling.
- The product is a rapid-setting concrete that sets within minutes and allows building on the post within a couple of hours.
- The bag's standard instructions (two bags per hole, 48-inch depth) are for typical soil and climate, not frozen-ground conditions.
Details Worth Noting
- Concrete instructions: Dig the hole about 4 feet 6 inches deep (4 feet and change) for a fence that will be 11 feet total, using a 12-foot post that can be trimmed at the top if dug too deep.
- Concrete instructions: Set the base of the post in the hole, adjust it by lifting and pushing away from the string until the post just touches the string while level, using a 5 to 6 foot level for the leveling itself.
- Concrete instructions: Hold the post in position, pour the bag of rapid-setting concrete all around the hole, then add water while the post is held in place; the speakers add water for about 20 seconds using city pressure at roughly 7 liters per minute, since the bag calls for 2.8 liters per bag.
- Concrete instructions: Let it set without bracing (bracing may disturb the post), then backfill the top couple of feet with clay and pound it down with a tamper so frost acts as a lid holding the post in place.
- Concrete instructions: Keep away from breathing the dust and step back once poured, since the concrete is described as toxic and there was no wind to disperse it that day.
- The speakers note that in this region shallow wells are common because clay holds water, and water was already pooling in the hole.
Bottom Line
In clay soil that holds water and freezes, the reliable approach is a level, string-guided, rapid-setting concrete set with about 20 seconds of water and a clay cap tamped on top, rather than gravel or the bag's default two-bag, standard-depth method.
