Can You Make Plumb Paper Of Wall For Shower?

Remodeling a bathroom is one of the most rewarding yet challenging DIY projects you can undertake. One of the most common frustrations homeowners face is discovering that their existing studs or walls are not perfectly vertical, leading to awkward tile cuts and potential water drainage issues. If you are staring at your framing and wondering, “Can you make plumb paper of wall for shower?”, you are not alone. This question often stems from a confusion between structural leveling and waterproofing layers. In this guide, we will clarify how to achieve a perfectly plumb surface for your shower tiles while ensuring your moisture barrier—often referred to as “paper” or building felt—is installed correctly to protect your home.

Understanding the Terminology: Plumb vs. Paper

Before we dive into the tools and techniques, it is crucial to distinguish between two critical concepts in shower construction: plumb and paper.

Plumb refers to the vertical alignment of a wall. A wall that is “plumb” is perfectly perpendicular to the floor (90 degrees). If a wall is out of plumb, your tile lines will look crooked, and water may not drain correctly toward the shower pan.

Paper, in the context of older or traditional shower construction, usually refers to 15-pound or 30-pound asphalt-saturated building felt (tar paper). This material acts as a secondary moisture barrier behind the cement board or directly over the studs in traditional mortar bed showers.

So, can you make the paper plumb? Technically, no. The paper conforms to the shape of the studs. However, you can make the wall assembly plumb before or during the installation of the paper and backer board. The goal is to ensure the final surface where you apply your tile is perfectly vertical.

Why Plumb Walls Matter for Showers

You might be tempted to skip the leveling process if the deviation seems minor, but this is a costly mistake. Here is why precision matters:

1. Aesthetic Integrity: Tile is rigid. If the wall behind it is bowed or leaning, your grout lines will widen and narrow inconsistently. This is visually distracting and screams “amateur work.”
2. Water Drainage: While the shower floor slope handles most water, vertical walls must guide water down efficiently. Severe leans can cause pooling in corners.
3. Fixture Installation: Installing shower valves, niche shelves, and glass doors requires square and plumb surfaces. An out-of-plumb wall can make installing a frameless glass door nearly impossible without expensive custom shimming.

According to industry standards, the tolerance for wall flatness is typically 1/8 inch in 10 feet for large format tiles. For standard subway tiles, you have slightly more leeway, but aiming for perfect plumb is always the best practice.

Step-by-Step: How to Make Your Shower Walls Plumb

If your studs are not plumb, do not panic. You have several methods to correct this before you even think about installing your moisture barrier (the “paper”) or cement board.

Method 1: Shimming the Studs (Best for New Construction or Gut Renovations)

This is the most professional approach. You adjust the framing itself.

1. Identify the High and Low Points: Use a long level (4-foot or 6-foot) or a laser level. Place it vertically against the studs. Mark where the stud bows in or out.
2. Select Your Shims: Use composite shims or cedar wood shims. Composite shims are preferred in wet areas as they do not rot or compress over time.
3. Attach the Shims:
   • If a stud bows in (away from the room), shim it out.
   • If a stud bows out (into the room), you may need to plane it down or sister a new straight stud alongside it.
   • Secure shims with construction adhesive and screws. Trim the excess shim material flush with the stud face using a utility knife or oscillating tool.
4. Verify: Run your level across multiple studs to ensure they are all in the same vertical plane.

Method 2: Using Furring Strips

If the wall is significantly out of plumb (more than 1/2 inch), shimming every stud might be tedious. Instead, you can install horizontal furring strips.

• Install 1×3 or 2×3 lumber horizontally across the studs.
• Use shims behind the furring strips at each stud location to create a perfectly flat and plumb plane.
• This method also creates an air gap, which can help with drying if designed correctly, though in a shower, the primary goal is a solid substrate for tile.

Method 3: Adjusting with Cement Board and Thinset

If the deviations are minor (less than 1/4 inch), you can correct them during the backer board installation.

• Apply a thicker layer of thinset mortar behind the cement board in the low spots.
• Press the board firmly against the high spots.
• Use spacers to maintain consistent gaps.
• Note: Do not rely on thinset to fill gaps larger than 1/4 inch, as it may shrink and crack, compromising the tile bond.

Installing the Moisture Barrier (“The Paper”)

Once your framing is plumb, it is time to address the “paper” aspect of your query. In modern US construction, we often use liquid waterproofing membranes or sheet membranes (like Kerdi or Schluter). However, if you are using traditional building felt (tar paper):

1. Overlap Correctly: Start from the bottom and work your way up. Each subsequent layer should overlap the previous one by at least 2 inches. This ensures water flows over the paper, not behind it.
2. Secure Properly: Use galvanized roofing nails or staples designed for building paper. Do not tear the paper.
3. Integrate with the Pan: The bottom edge of the wall paper must overlap the flange of your shower pan liner. This is critical. If the paper is behind the liner, water will get trapped in the wall cavity, leading to mold and rot.

For more detailed information on traditional shower construction methods, you can refer to general construction principles outlined on Wikipedia’s page on Shower Construction.

Comparison: Traditional Paper vs. Modern Membranes

Expert Insight: While building paper is code-compliant in many jurisdictions when used with a mortar bed, modern sheet membranes offer superior peace of mind because they create a continuous, monolithic barrier that doesn’t rely on nail holes being sealed perfectly.

Common Mistakes to Avoid

• Ignoring the Corners: Corners are the most likely place for leaks. Ensure your paper or membrane is folded correctly or uses pre-formed corner pieces.
• Not Checking for Plumb After Backer Board: Installing cement board can sometimes introduce new irregularities. Always check your final surface with a level before tiling.
• Using Drywall in Wet Zones: Never use standard green board or drywall in a shower area. Use cement board, fiber-cement board, or foam boards designed for wet environments.

FAQ Section

1. Can I use tar paper directly over drywall in a shower?

No. Standard drywall, even moisture-resistant “green board,” is not suitable for direct water exposure in a shower. Tar paper is a moisture barrier, not a waterproofing layer for interior finishes. You must use a proper tile backer board (like cement board) or a dedicated shower system.

2. How much does it cost to fix an out-of-plumb shower wall?

If you are doing it yourself, the cost is minimal (shims and screws: under $50). If you hire a professional framer or tile setter to correct significant framing issues, it could range from $200 to $500 depending on the severity and local labor rates. It is far cheaper than fixing failed tile work later.

3. Does the wall need to be perfectly plumb for small subway tiles?

Small tiles (like 3×6 inch subway tiles) are more forgiving than large format tiles. However, “forgiving” does not mean “ignore it.” A wall that is out of plumb by more than 1/8 inch over 4 feet will still result in noticeable lippage and uneven grout lines. Aim for plumb regardless of tile size.

4. What is the best tool to check if my wall is plumb?

A 4-foot spirit level is the standard tool. For higher precision, especially over tall walls, a laser level is highly recommended. It projects a perfectly vertical line across the entire wall, making it easy to spot bows and leans instantly.

5. Can I shim the cement board instead of the studs?

Yes, but only for minor adjustments (up to 1/4 inch). You can use plastic shims behind the cement board or build up thinset mortar. For larger corrections, you must address the framing (studs) directly. Shimming heavy cement board excessively can lead to instability and tile cracking.

6. Is “plumb paper” a real product?

No, “plumb paper” is not a specific product name. It is likely a colloquial mix-up of terms. You may be thinking of “building paper” (tar paper) used to make walls watertight, or the act of making the wall “plumb” before installing the paper. Always clarify with your supplier whether you need waterproofing materials or leveling tools.

Conclusion

So, can you make plumb paper of wall for shower? The answer is a nuanced no—you don’t make the paper plumb; you make the wall plumb, and then you install the paper (or modern membrane) to protect it. Achieving a plumb wall is the foundation of a professional-looking, durable shower. By taking the time to shim your studs or adjust your framing, you ensure that your tile work looks crisp, your fixtures fit perfectly, and your waterproofing performs as intended.

Don’t rush the prep work. The hours you spend ensuring your walls are straight and your moisture barrier is secure will save you from costly repairs and aesthetic regrets down the road.

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