Post Hole Depth and Footing Size for Estate Gates in Georgetown Limestone Soil
The auger is supposed to find solid ground. Around Georgetown, TX it often quits on caliche two feet down and leaves a hole that only looks finished. The breakdown sitting on estate gates georgetown new trouble lists footing sizes in order of post height and leaf weight, because an estate gate post carries far more leverage than a fence post and a short hole shows up as a leaning frame within a season.
How deep does the hole need to go?
The hole needs to reach at least a third of the post height above grade, and deeper for a dual swing entry that weighs several hundred pounds. A ten foot steel post wants about three and a half to four feet in the ground. Limestone soil makes that slow work, so the crew brings a rock bit or a hammer drill instead of stopping short and calling it done.
What do clay and caliche do to a footing?
Clay swells in a wet week and shrinks in drought, and a footing set only in clay moves with it. Across Williamson County the clay layer is often shallow, with caliche or fractured limestone underneath. Anchoring the footing into that harder layer keeps the post from rocking, while a belled base spreads load into the clay above it.
How wide should the footing be?
A footing should be at least three times the width of the post, so a six inch tubing post wants an eighteen inch round hole. Tall posts that carry wide leaves need more. A narrow hole with a lot of concrete depth still pivots at the top, which is why width counts as much as depth on a single swing leaf and more on a double one.
Where does the water go?
Water has to leave the base of the post, or the weld at the bottom plate rusts from the inside. Spring storms push runoff toward the San Gabriel River and the Lake Georgetown watershed, and the same water pools around any footing set in a bowl of clay. A few inches of gravel under the post and a crowned concrete top shed it away from the steel.
How long before the leaves can hang?
Concrete reaches workable strength in about a week, and heavy leaves wait longer than that. Hanging a frame on green concrete lets the post lean a fraction at a time, and the sag shows up months later at the latch. Posts are checked plumb in both directions before the pour and again after the first week, before any hinge is bolted on.
What gets checked before digging?
Every hole starts with a utility locate and a look at how the drive slopes. A footing near a drainage swale or a septic line is moved or reshaped before the auger starts. On a lot near Interstate 35 the older fill soil can change the plan, so a test hole comes first and the real depth is settled from what the bit pulls up.