Littleton Footings and Piers

Watch an auger come up out of a fresh hole sometime. The material changes as it climbs, and it changes in order: dark yard soil first, then whatever the builder pushed around forty years ago, then something stiffer and paler, and eventually the stuff we actually came for. Every layer lands on the pile in order, so the pile is a cross section of your property laid out sideways on a tarp.

We read it before deciding anything. A deck, a shop, a covered patio, an addition: all of them ride on whatever sits at the bottom of a hole, and the only honest way to know is to open one. Littleton makes that interesting, because the ground under Columbine and the ground out toward Ken Caryl are not the same material at all.

What the auger brings up, in order

The top foot or two is almost never structural. Yard soil, old landscape fill, sometimes buried construction debris nobody mentioned at closing. Fine for growing grass, useless for holding weight. We drill through it.

Below that, most of the flat ground in town hands us clay. Stiff, pale, sticky when wet, and perfectly able to carry a load right up until its moisture changes. Head toward the foothill edge and the profile shifts fast. Around Ken Caryl we find decomposed granite, cobble, sometimes solid rock a few feet down. Excellent bearing, slow drilling. The newer streets near Highland Walk add their own wrinkle: engineered fill from development days, which can be very good or very indifferent.

Reading the pile beside the hole

Depth and spacing get decided together

People ask how deep as if depth were one number. It isn't. Depth and spacing trade against each other: fewer supports means each carries more, so each goes deeper or wider. More supports spread the load and can be shallower, but you're buying more holes.

Two floors set the minimum. Frost is one, and on the Front Range that means planning for something in the range of two and a half to three feet before load even enters the conversation. Bearing is the other, and on clay bearing wins. We keep going until the shaft has the side friction and end capacity to hold without riding the layer that moves every season. Our engineer sets the numbers. We don't eyeball it.

Water in the hole, and the gravel myth

Here's advice you'll read online that we'd like to bury: throw a few inches of gravel in the bottom of the hole for drainage. On sandy ground, harmless. On the clay under most of this town, you just built a bathtub. Water finds the gravel, the clay holds it there, and the bottom of your pier spends every winter in a wet pocket that freezes and pushes.

What works is keeping water away up top. Grade falling away, downspouts carried past the posts, sprinkler heads aimed elsewhere. Down in the hole we want concrete against undisturbed soil. No cushion, no soft spot, no drilling crumbs left in the bottom. We clean shafts before we fill them, every time.

Drilling through a Colorado year

Late summer through fall is the sweet spot. Dry ground, shafts that stand open, no mud. Spring works but runs slower, since saturated clay sloughs about as fast as the auger clears it. Summer is fine when we place early instead of chasing an afternoon storm.

Winter changes less than people expect. Frozen ground is a lid, not a wall. The top foot comes out in chunks and everything under it drills like ordinary dirt. What we won't do is pour against frozen material or leave fresh piers bare on a night headed for single digits. Heated water, blankets over the tops, and every hole drilled and filled the same day.