Overview: Dig accurately and use the proper tools
1 of 1The big 4 posthole tools
If you have more than a couple of postholes to dig, don't stop at a
shovel and a clamshell digger. You'll treasure two more tools just
as much. Pick up a tile spade. The long, narrow blade will get you
places no other shovel can. Also get a tamper-end digging bar.
So, big shot, you think you know
how to dig postholes, eh? Sure you
do—anyone can dig a hole. But how
hard do you want to work, and how
often do the holes end up in the
wrong spot and you have to start
over? Here are a few tips to get
perfectly placed holes—with a little
less sweat on your part.
Step 1: String your line and pound the stakes
1 of 2Drive stakes
Drive stakes to mark the center of each posthole.
2 of 2Post-marking tip
Push a small nail through your string line to mark post centers.
String a line marking the outside edges
of the posts. Mark the post centers on
the line by untwisting the string and
pushing a nail through the strands. You can
fine-tune the nail position just by sliding it to
the exact location. Then pound stakes to mark
the center of the holes. If you're using 4x4 posts,
that will be just under 2 in. from the string.
Step 2: Carve out a soil divot with a spade
1 of 1Center the hole
Dig around the stake to center the hole.
Set the string aside so
you don’t wreck it while
digging. And don't just
start digging away; drill
yourself a pilot hole
first. Carve out a round
plug to outline the
posthole. That'll get
you started in exactly
the right spot. Throw
the dirt onto a tarp to
protect your lawn.
Step 3: Loosen earth with a tile shovel
1 of 1Slice through the topsoil
A special tile shovel slices through roots and turf and gets the hole started more easily.
Unless you have very soft
soil, you'll work way too
hard digging with just a
clamshell digger. Loosen
the soil and carve away
at the sides with the
tile spade. It'll easily slice
through small roots.
Step 4: Use your clamshell digger
1 of 1Clamshell digger
A clamshell digger removes loose soil quickly.
Plunge the open clamshell
digger blades into
the loosened soil and
grab a load of fill.
Step 5: Use a reciprocating saw on large roots
1 of 1Saw through large roots
A recip saw will reach down the hole and cut those tough roots, especially with a long blade.
Don't kill yourself chiseling
out roots. Just use
a recip saw with a long,
coarse blade and poke it
right into the soil at the
ends of the root and cut it off.
Step 6: Dislodge rocks with a digging bar
1 of 1Use a steel bar for rocks
Knock rocks loose with a steel bar and lift them out with the clamshell digger.
Pick out rocks from the hole
sides with your digging bar. Let
them fall into the hole and pluck
them out with your clamshell
digger.
Step 7: Tamp the soil with the other end
1 of 1Tamp the hole bottom
Pack the bottom of the hole to compress any loose soil.
Use the tamper end of the
digging bar to compact the soil
before setting posts or pouring
concrete. That prevents any
settling.
Step 8: Mark the post edge locations
1 of 1Center the post
Measure the post spacing again and mark the stringline.
Restring the line, pull
the nails and mark the
exact post edge locations
on the line with a
permanent marker.
Step 9: Cover holes with plywood
1 of 1Hole cover
If leaving the site, cover the holes for safety.
If you're walking away
from the postholes for
a while, cover them
with plywood. It
just might save a
broken leg and/or keep the sides
from caving in
during a storm.
Step 10: Set the posts
1 of 1Position the posts
Position and plumb the posts carefully before backfilling or adding concrete.
Place the posts with one side
brushing against the string
and the edge even with
your mark. Then hold
the post plumb while
you fill the hole. Pack
the soil with the
tamper end of the
digging bar every foot
or so.
Tip 1: Dig by hand unless...
1 of 1Rent a power auger
Power augers can speed up digging in rock- and root-free soils.
Power augers require a trip to the rental store and a
brawny friend. And they're worthless in clay or rocky
soil. The truth is, unless you have lots of holes to dig in
sand, it's often easier to dig by hand.
Tip 2: Use water and the back of your shovel
1 of 1Digging in clay
Lubricate the digger with water and rap it against a shovel to knock off sticky clay.
If you're digging in sticky clay soil, dip your
clamshell digger in a bucket of water so the
soil won't stick. Knock off clumps on the
back of the shovel. Spread a tarp to keep
dirt off your grass.
Tip 3: Small is beautiful
1 of 1Opt for easy digging
A small digger is usually easier to use than a large one.
Unless you're a body builder, avoid those giant,
heavy-gauge, fiberglass-handled clamshell diggers.
You'll just get exhausted; you're better off
with a smaller, lightweight digger.
