Installing posts in your yard for a fence, mailbox, or other structures often requires digging holes and setting the posts securely. Proper post hole digging and setting techniques allow your posts to stand straight, remain sturdy, and last for years. Follow this guide to learn the steps for successful post installation.
Choosing the Right Location
The first step in any post-hole digging project is planning where your posts need to go. Consider the following when choosing locations:
Spacing
Measure and mark where each hole should be dug. For fences, spacing is typically 6 to 8 feet between posts. Gates often need posts every 4 feet. Make sure spacing is even for best results.
Obstructions
Inspect above and below ground for any obstructions. Look for tree roots, pipes, electrical lines, boulders and more that could block digging. Adjust post locations as needed to avoid these.
Soil Conditions
Ideally, posts should be set in undisturbed native soil which offers greatest stability. Avoid digging right next to concrete or pavement if possible.
Property Lines
When installing fence or mailbox posts, be sure to dig holes 1-2 inches inside your property line to avoid disputes. Utility markers also help identify property boundaries.
Proper planning of post hole placement from the start prevents problems later on.
Selecting the Right Post Size
Post size is another key consideration when starting your project:
Depth
Dig holes deep enough so posts extend 1/3 their total length into the ground. For example, an 8 ft post requires a hole about 2 1⁄2 feet deep.
Width
Holes should be 2 to 3 times wider than the post diameter. A 4×4 inch post needs roughly a 12 inch wide hole for example.
Material
Common types are 4×4 inch pressure treated lumber, 6 inch diameter rot resistant wood rounds, or steel pipe. Choose based on budget and needs.
Take measurements beforehand to determine the required depth and width when digging holes for your particular posts.
Digging Equipment Options
Several digging tools and power equipment choices exist for digging post holes, each with pros and cons:
Post Hole Digger
A hand tool with two shovel-like blades that leverage against each other to cut and lift soil. Simple and inexpensive but requires more physical effort.
Power Auger
A gasoline or electric powered auger bit attaches to a drill and bores smooth, cylindrical holes. More expensive but easier than manual methods.
Tractor Auger
Tractors with a rear hydraulic auger are ideal for digging numerous holes in soil efficiently. Requires tractor access.
Excavator
Excavators make digging holes with an hydraulic auger quick work. The high cost makes renting one only practical for large projects.
Consider how many holes you need dug, soil conditions, and your budget when selecting the best digging tool for the job.
Preparing to Dig
Once you’ve determined where holes will go and chosen suitable equipment, some preparation makes digging easier:
Clear Away Obstacles
Remove any sod, rocks or roots around hole locations. Level and tamp down the area for stable footing.
Mark Locations
Use stakes and string to outline the post line. Flour or spray paint also marks individual hole spots clearly.
Call to Locate Utilities
Contact your utility companies to identify any buried electric, gas or water lines on the site and avoid them.
Taking these simple steps ahead of time prevents delays and hazards during the digging process.
Digging Post Holes
Now comes the tough part – digging the post holes! Follow these tips for best results:
Widen as You Dig
Gradually widen the hole as you go down maintaining a conical shape. The top should be flared to at least twice the post’s diameter.
Angle Sides In
Trim hole sides at a slight inward angle rather than straight up and down to allow easier post insertion later.
Stop at Correct Depth
Measure the hole depth periodically. Stop at specified depth for the post being used.
Break Up Compacted Soil
Use an auger, crowbar or pickaxe to loosen any hardened soil at the bottom for better post stability.
Level the Bottom
Ensure the bottom is as flat as possible for even contact and prevent posts from rocking.
Follow these guidelines when digging to get nicely shaped holes ready for posts.
Setting and Securing Posts
With proper holes dug, it’s time to set and secure the posts:
Place in Center
Position posts in the exact center of the holes for optimal stability. Brace temporarily if needed.
Align Vertically
Use a level on two adjacent sides to align posts perfectly vertical as they go in.
Fill In Backfill
Shovel backfill material such as gravel or dirt around posts in 6 inch layers. Pack firmly with a tamping tool.
Use Fasteners
Secure special metal fasteners like fence post spikes for extra anchoring in high load applications.
Crown with Concrete
Optional concrete around the top 2-3 inches provides extra support and protection from moisture damage.
Follow these steps when setting and securing posts in holes for long lasting stability.
Troubleshooting Hole Digging Problems
Despite best efforts, some issues can arise when digging post holes:
Hard, Rocky Soil
Use a pickaxe and pry bar to break up compacted soil. Watering for several days before can also help soften the ground. Switching to a power auger is recommended for large projects.
Roots Present
Expose tree and shrub roots with a shovel then use loppers or saw to cut away roots around the planned hole location.
Existing Buried Lines
If utility lines are encountered, stop digging and call the utility company to determine next steps before proceeding.
Hole Too Narrow
Widen the top gradually with a shovel, making sure sides angle in, until post can be inserted properly.
Holes Too Shallow
Measure and re-dig holes to the full required depth for complete stability. Add concrete footings if posts are still too short.
With patience and the right approach, most post hole digging challenges can be solved.
Finishing Touches
Some final steps complete your post installation project:
Backfill Holes
Shovel any leftover dirt back around holes, water thoroughly and tamp down to prevent settling.
Brace Temporarily
Use plywood bracing secured with blocks or screws to keep posts plumb as backfill compacts.
Remove Braces
Let posts sit 1-2 weeks until backfill settles then remove temporary braces.
Check Level & Plumb
Recheck post alignment and adjust as needed for a professional looking installation.
Take time with finishing steps for best long term results from your installed posts.
Frequently Asked Questions
Still have questions about digging post holes? Here are some common FAQs:
How deep should I dig holes for 6 foot posts?
For maximum stability, dig holes for 6 foot posts about 2 feet deep so 1/3 of the post length is underground.
What size hole do I need for 4×4 posts?
A good rule of thumb is to dig holes 2-3 times the post width, so approximately a 12 inch diameter hole for common 4×4 posts.
Can I just use a shovel to dig post holes?
Yes, shovels can be used to dig holes, especially in soft soils. But consider renting or investing in a power auger for large projects with harder, rockier ground.
What is the easiest way to dig post holes in hard ground?
For hardened soils, gas-powered augers are easiest. Hydraulic earth augers on tractors or excavators are best for large jobs. Pre-soaking the holes a few days before digging also helps significantly.
How do I stabilize a post in loose soil?
Setting posts in concrete instead of just backfill dirt is best for loose, sandy soils. A footer around the bottom of the hole prior to post installation also improves stability.
Digging holes and setting posts properly allows them to stand securely for many years supporting fences, mailboxes, lamps and other structures. Follow the techniques in this guide for your next post installation project. With the right planning and tools, you can gain experience and confidence in digging holes and setting posts like the professionals.
Conclusion
Digging post holes and installing posts securely is crucial to building fences, signage, mailboxes and more. By planning carefully, selecting the right tools for the job, properly excavating holes, placing posts plumb in the center, backfilling firmly around them, and allowing time to settle, you can achieve a sturdy, long-lasting post foundation. Patience and following proven methods will lead to success and satisfaction with your completed project, and the knowledge to install posts like an expert.
So don’t shy away from post installation tasks – with this guide’s step-by-step instructions, you can dig perfect holes and set secure posts for years of service. Just take it one hole at a time!