Fix Shum Between Post Anchor And Post If Not Plumb

There is nothing more frustrating than finishing a deck frame only to realize your vertical posts aren’t perfectly straight. When you encounter Shum Between Post Anchor And Post If Not Plumb, it can feel like a major structural setback that requires tearing everything down. However, with the right techniques and materials, you can correct these alignment issues safely and effectively without compromising the integrity of your outdoor living space.

In this guide, we will walk you through professional methods to address gaps caused by unplumb posts, ensuring your structure remains safe, stable, and up to code. Whether you are a seasoned contractor or a weekend DIY warrior, understanding how to properly shim and adjust is crucial for long-term durability.

Why Does Shum Occur Between Post Anchors and Posts?

Before fixing the issue, it is essential to understand why it happens. “Shum” (commonly referred to as shim or gap) occurs when there is a misalignment between the metal post anchor embedded in the concrete and the wooden post itself.

Common Causes of Misalignment

• Concrete Settlement: The ground may shift slightly after the concrete cures, tilting the anchor.
• Installation Error: The anchor was not held perfectly plumb while the concrete was wet.
• Wood Warping: The lumber itself may have bowed or twisted during storage.
• Anchor Type: Some surface-mounted anchors allow for less adjustment than cast-in-place models.

According to general construction principles, even a small deviation at the base can result in significant lean at the top of a tall post. This is why addressing the Shum Between Post Anchor And Post If Not Plumb immediately is critical.

Is It Safe to Shim an Unplumb Post?

This is the most common question homeowners ask. The short answer is: Yes, but with strict conditions.

Not all shims are created equal. Using random pieces of scrap wood or compressible materials like cardboard can lead to structural failure over time. Wood compresses, rots, and shifts, which defeats the purpose of a stable foundation.

The Golden Rule of Shimming

You must use non-compressible, rot-resistant materials. The goal is to fill the void without creating a “soft spot” that allows the post to wobble under load.

For more detailed information on structural wood connections, you can refer to Wikipedia’s article on Light-frame construction, which outlines the importance of rigid connections in framing.

Step-by-Step: How to Fix Shum Between Post Anchor And Post If Not Plumb

If your post is already installed and you notice a gap or lean, follow this professional workflow to correct it.

Step 1: Assess the Degree of Lean

Use a high-quality 4-foot level. Place it against two adjacent sides of the post.

• Minor Gap (< 1/4 inch): Can be fixed with shims alone.
• Moderate Lean (1/4 – 1/2 inch): Requires shimming and potentially loosening the bolt.
• Severe Lean (> 1/2 inch): May require removing the post and resetting the anchor.

Step 2: Loosen the Fasteners

Do not try to force a plumb post while the bolts are tight. This can split the wood or strip the anchor threads.

1. Use a socket wrench to loosen the nuts on the anchor bolts.
2. Leave them loose enough so the post can move, but not so loose that it falls over.

Step 3: Insert Proper Shims

This is where you address the Shum Between Post Anchor And Post If Not Plumb.

• Material: Use tapered cedar shingles. They are dense, non-compressible, and naturally resistant to decay.
• Placement: Insert the shims into the gap between the post and the anchor bracket.
• Technique: Drive the shims in gently with a hammer. Ensure they are seated firmly. If the gap is on one side, shim that side until the post reads “plumb” on your level.

Step 4: Check for Plumb Again

Once the shims are in place, check your level again.

• Adjust the shims by tapping them deeper or pulling them out slightly.
• Ensure the post is plumb in both directions (front-to-back and side-to-side).

Step 5: Tighten and Trim

1. Once perfectly plumb, tighten the anchor bolts securely. Do not overtighten, as this can crush the wood fibers.
2. Use a utility knife or a flush-cut saw to trim the excess shim material sticking out from the bracket.
3. Apply a bead of exterior-grade caulk around the base if desired to prevent water intrusion, though proper flashing is preferred.

Alternative Solutions for Severe Misalignment

Sometimes, shimming isn’t enough. If the anchor itself is tilted significantly, you need a different approach.

Option A: Adjustable Post Bases

Modern hardware stores sell adjustable post bases. These feature a sliding plate or a screw-jack mechanism that allows you to fine-tune the position of the post after the concrete has cured. This eliminates the need for manual shimming and provides a cleaner look.

Option B: Epoxy Anchors

If the original anchor is badly positioned, you can sometimes drill new holes into the concrete and use high-strength epoxy anchors to secure a new bracket. This is labor-intensive but saves you from breaking up the entire concrete footing.

Option C: The “Sister Post” Method

For decorative posts that carry little structural load, you can build a box around the unplumb post to make it appear plumb. However, do not use this method for structural support beams. This is purely cosmetic and does not fix the underlying Shum Between Post Anchor And Post If Not Plumb issue regarding load transfer.

Expert Tips for Preventing Future Issues

Prevention is always cheaper than correction. Here is how to ensure your next project starts straight:

1. Use a Post Level: These are specialized levels with magnets that attach to square posts, allowing you to hold them plumb with one hand while pouring concrete.
2. Brace Before Pouring: Never rely on holding the post by hand. Use 2×4 braces screwed into the post and staked into the ground to hold it perfectly vertical while the concrete sets.
3. Check Anchor Alignment: Before the concrete hardens, double-check the anchor bracket. Use a small level on the bracket itself, not just the post.
4. Allow Cure Time: Wait at least 24–48 hours before attaching heavy beams. Premature loading can shift the uncured concrete.

FAQ Section

Q1: Can I use plastic shims for deck posts?

A: Yes, heavy-duty plastic shims are acceptable for small gaps (under 1/8 inch). However, for larger gaps, cedar shingles are preferred because they provide a tighter friction fit and are less likely to slip under vibration.

Q2: What is the maximum gap I can shim?

A: Generally, you should not shim more than 1/2 inch. If the gap is larger, the leverage on the bolt increases significantly, which can lead to failure. For gaps larger than 1/2 inch, consider resetting the anchor or using an adjustable base.

Q3: Does shimming void the warranty on my post anchor?

A: Most manufacturers allow for minor shimming as long as non-compressible materials are used. However, always check the specific installation instructions provided by the manufacturer (e.g., Simpson Strong-Tie or DeWalt) to ensure compliance.

Q4: Should I treat the shims with preservative?

A: If you use cedar shingles, no treatment is necessary as cedar is naturally rot-resistant. If you use pressure-treated wood scraps, ensure they are dry before installing to prevent trapping moisture against the main post.

Q5: Can I shim a post that is already supporting a roof?

A: This is risky. If the post is load-bearing a roof, you must temporarily support the roof structure with jack posts before loosening the anchor bolts. Never remove support from a load-bearing post without temporary bracing.

Q6: What tools do I need to fix shum between post anchor and post if not plumb?

A: You will need a 4-foot level, a socket wrench set, a hammer, cedar shingles or plastic shims, a utility knife, and possibly a drill if you need to add new bracing.

Conclusion

Dealing with Shum Between Post Anchor And Post If Not Plumb doesn’t have to be a nightmare. By understanding the cause of the misalignment and using the correct non-compressible materials like cedar shingles, you can achieve a structurally sound and visually appealing result. Remember, patience and precision during the installation phase save hours of corrective work later.

Always prioritize safety by checking local building codes and using proper bracing techniques. If you found this guide helpful, please share it with your fellow DIY enthusiasts on social media. A well-built deck is a joy for years to come, and proper post alignment is the foundation of that longevity.