How to Fix Settling Concrete Posts

Contact the local authority for your area regarding buried hazards and utilities before you begin digging. The national website Call811.com puts you in contact with local utilities, and with several days’ notice, a representative will come out to mark the location so that you may safely proceed.

Run a string between established posts in the line or to mark your new line of posts. The string line helps you align each post with the others in the formation.

Dig around and remove the problematic posts, or begin a new fence line and start with fresh holes. Pile the topsoil separately from soil extracted from deeper within the holes. Firm the remaining dirt within each hole along the sides and bottom.

Dig each hole to a depth fitting the height and width of the posts, the planned use of the fence and conditions that affect the fence. Posts are typically set at a depth equal to one-third to one-half of the length of the posts. A 10-inch diameter hole generally suits a 4-inch-by-4-inch post. The Package Pavement website suggests using a larger, dish-shaped hole for loose soils such as sand.

Verify that the post is vertically straight and centered in the hole, and check the post’s alignment with others in the fence row before backfilling.

Fill the hole with gravel. The Ask the Builder website recommends using crushed, angular gravel in windy locations, as it offers a foundation that mimics the solidity of rock. In other instances, pea gravel may suffice. Add approximately 6 inches of gravel at a time, then use an iron bar or equally weighty substitute to compact the gravel by repeatedly tamping around the circumference of the post. Recheck the alignment of the post after compacting each layer.