Plumbing the 4x4 Line Posts of a Four-Board Goat Paddock Fence With a Magnetic Post Level: A String Line, 8-Foot Centers, and 36 Inches in the Ground

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A board fence shows every crooked post, because the boards run straight and the eye follows them. For a small goat or sheep paddock, set 4x4 line posts on 8-foot centers along a tight string, strap a post level on each one, and pack the soil a few inches at a time so the post stays plumb both ways.

How do you keep 4x4 line posts plumb and in line for a board fence?

Stretch a string between the end posts, set each line post against it, and strap a two-vial post level on a corner. Add a few inches of moist soil, tamp it, and check both vials before the next lift. Keep posts no more than 8 feet apart and at least 36 inches deep.

The University of Georgia bulletin Fences for Horses describes the hand method. Place the post, line it up with the others using a guide wire or string, then fill and tamp a few inches at a time in soil that is moist but not overly wet.

It adds that the bottom 6 inches matter most and can't be packed if the hole is filled before tamping starts. It also advises against concrete around wood posts, since it reacts with the wood and shortens post life.

The NRCS Massachusetts fence specification guide sets the board fence numbers. Wood post spacing may not exceed 8 feet on center, and wood line posts go in at least 36 inches, with gate and corner posts at 48 inches.

Board Fence Numbers for a Small-Livestock Paddock

Item	Spec	Source
Line post size	4 x 4 in. minimum (small livestock)	NRCS MA
Post spacing	8 ft. on center, maximum	NRCS MA
Line post depth	36 in. minimum	NRCS MA
Corner and gate posts	48 in. minimum	NRCS MA
Boards	1 x 6 minimum, 8 ft. or longer, at least 3 boards	NRCS MA
Goat and sheep fence	4 boards, 46 in. minimum height	NRCS MA
Nails	Two 16d hot-dipped galvanized per board per post	NRCS MA

The NRCS guide also wants board length to be twice the post spacing, with seams staggered on the posts. On 8-foot centers that means 16-foot boards, each spanning two bays.

Laying Out the Run

UGA suggests making a rail fence run an even multiple of the post spacing, so you don't end with an odd 2-, 3-, or 5-foot section. A 96-foot side on 8-foot centers gives 12 bays and 13 posts counting both ends.

A gauge pole cut to the spacing, as the UGA bulletin suggests, is quicker than a tape at every hole. Mark the digging tool at the target depth too, so every hole comes out the same.

Materials and Tools

• Magnetic post level with vials on two faces and a strap or band for wood posts
• Ground-contact treated 4x4 line posts, long enough for 36 inches in the ground plus the fence height
• Mason's string and two stakes or the set end posts to tie it to
• A post-hole digger with a depth mark, and a gauge pole cut to 8 feet
• A tamping bar or a roughly 1-inch rod for packing soil
• Treated 1x6 boards, 16 feet long, and 16d hot-dipped galvanized nails

Setting Steps

1. Call before you dig. The NRCS guide says to have buried and overhead utilities checked before any fence work starts.
2. Set the ends. Install the corner or end posts first at 48 inches deep, then run a string between them at about post-top height.
3. Space the holes. Walk the gauge pole down the line and mark a hole every 8 feet.
4. Dig to the mark. Dig each line post hole to 36 inches, a few inches wider than the post on every side.
5. Strap on the level. Fasten the post level around a corner so one vial reads the face along the fence and the other reads the face across it.
6. Touch the string. Stand the post so its outside face just meets the string without pushing it out of line.
7. Pack the bottom. Add a few inches of moist soil and tamp it hard, then check both vials before adding more.
8. Work up in lifts. Repeat a few inches at a time to the top, nudging the post back to plumb while the hole is still open.
9. Sight the row. After every few posts, look down the line from an end post to catch one that sits proud of the string.

Hanging the Boards

The NRCS guide places boards on the livestock side in corrals and other high-pressure areas, so goats push boards against posts instead of off them. Each board gets two 16d galvanized nails at every post, or two 3-inch decking screws with the same coating.

Ring-shank, spiral, or screw-shank nails hold better than common nails, according to the same guide. Stagger the seams so no two boards in a bay end on the same post.

Line Post Mistakes

• Filling the whole hole and then tamping the top, which leaves the bottom 6 inches loose
• Checking only the face along the fence, so the post leans in or out of the paddock
• Pouring concrete around treated wood line posts out of habit
• Pulling the string so slack that it sags between the end posts

For the digging itself, see hand-digging 8-inch holes for wood line posts. Deeper corner holes are covered in digging 48-inch gate post holes by hand.

If goats or chicks share the paddock and slip through the bottom gap, a strip of mesh along the lowest board helps. Pick the opening and wire weight from the hardware cloth mesh size and gauge guide.

FAQ

Do line posts really need to be 36 inches deep?

That is the NRCS Massachusetts minimum for wood line posts in a board fence. The UGA bulletin gives 2 feet as a general floor for wood line posts, so go with the deeper figure for a board fence that livestock will lean on.

Can I set the posts in concrete instead?

UGA does not recommend concrete around wood posts. Well-tamped soil, or soil mixed with some small rocks, holds better over time.

Why does the level need two vials?

One vial only reads one face. A post can be plumb along the fence and still lean toward the paddock, which shows once the boards go on.