Do Walls Need to Be Perfect Before Tiling? The Ultimate Guide to Tiling Uneven Walls

Hey there! If you‘re reading this, chances are you‘re planning a tiling project and have discovered that your walls are a bit uneven. Not to worry! While perfectly smooth walls make tiling easier, with the right approach, you can absolutely tile over less-than-perfect surfaces.

I‘ve tiled my fair share of wavy walls, so I‘m going to walk you through how to assess and fix unevenness before you tile. Trust me, taking the time to properly level and prep will save you a ton of frustration down the road and ensure your tiles look amazing for years to come. Let‘s get started!

How Common Are Uneven Walls?

According to industry surveys, over 60% of walls have some degree of unevenness or slope. This is especially true for older homes built before drywall leveling standards became more precise. So if your walls aren‘t perfectly plumb and smooth, you‘re definitely not alone!

The National Association of Home Builders says any deviation of more than 1/4 inch over 48 inches on a wall surface should be addressed before tiling. So while perfection is not required, taking steps to repair major uneven spots is recommended.

Thoroughly Assessing Your Walls

The first and most important step before any tiling project is assessing the wall surface. Here‘s how I recommend inspecting for unevenness:

• Look closely for any visible bumps, ridges and dips in the flat plane of the wall. Mark any obvious issues.

• Use a 4-6 foot straight edge or long level and scan the entire surface. Mark any spots that deviate more than 1/8 inch.

• Check all joints and corners with a shorter level to make sure they‘re plumb and square.

• Tap on the wall and listen/feel for hollow spots that indicate potential moisture or decay issues.

• Identify any previous repairs like spackling that may become problematic under tiles.

Fixing underlying problems with your wall prior to tiling will make your installation stronger and longer-lasting.

Leveling and Repair Options

Okay, you‘ve done your inspection and determined the wall needs some leveling and patching. No problem, there are several effective options:

Furring Strips

Furring strips are thin wood or plastic strips that attach horizontally across studs or directly to the wall surface. Pros:

• Inexpensive and easy to install
• Offer flexibility if secured to studs
• Allow inspection of wall behind

Cons:

• Less durable than other options
• Can show seams on finished surface

I suggest using furring strips for minor unevenness in non-wet areas.

Skim Coating

Applying a thin layer of joint compound, plaster or specialty leveling compound can smooth over minor flaws up to 1/4 inch deep.

Pros:

• Simple and low cost
• Multiple thin coats build up gradually

Cons:

• Requires sealing for moisture resistance
• Can crack if underlying wall moves
• Dries quickly so work fast!

This is my preferred method for small fixes on drywall.

Mortar Bed

Wet mortar applied 1/4 to 3/4 inch thick can level significant variances.

Pros:

• Handles deeper unevenness
• Durable and moisture resistant
• Can be applied in multiple layers

Cons:

• Heavy and permanent
• Slow drying time
• Can crack if substrate shifts

Use this technique for substantial smoothing and correction in shower and tub surrounds.

Backerboard

Backerboard like Durock or HardieBacker secures tightly to studs, creating an ideal subsurface for tile.

Pros:

• Cement boards are inherently level
• Won‘t deteriorate from moisture
• Allows access to inspect behind

Cons:

• Heavier than other options
• Securing tightly to uneven walls takes finesse
• Joints must be taped carefully

I use backerboard for tile installations onto especially wavy or questionable walls.

There are also many specialty leveling and patching compounds made for walls available at hardware stores that each have their own benefits. Don‘t be afraid to ask associates for recommendations on products best suited for your specific unevenness situation and tile material.

Tiling Building Codes and Standards

Most residential building codes require walls to be relatively flat prior to tiling. Per the International Residential Code (IRC):

• Maximum deviation of 1/4 inch over 48 inches vertically and horizontally
• No gaps or variation exceeding 1/16 inch adjacent to framing

Many tile manufacturers also specify maximum allowable variation of 1/8 inch over 4-6 feet. Abiding by these standards helps ensure your tile lasts.

Moisture Concerns with Uneven Walls

If your uneven wall has existing moisture damage, you must address and repair this prior to tiling! Use a moisture meter to test for potential issues. Signs include:

• Visible water stains or bulging
• High moisture meter readings
• Musty smells or peeling paint/wallpaper

Excess moisture under tile can lead to degradation of the bonds and serious mold growth. Let any repairs fully dry before moving forward.

I highly recommend using a waterproofing paint or roll-on membrane prior to tiling in bathrooms, laundry rooms and other wet areas. RedGard is a great product for this!

Tile and Adhesive Products for Uneven Walls

Choosing the right tile and adhesive is critical for success on uneven walls. Here are my top tips:

• Tile: Pick smaller and/or mesh-backed tile formats which flex rather than large heavy tile. Mosaics are great!

• Adhesive: Use a premium modified thinset mortar designed for uneven installation.

• Grout: Epoxy or latex/polymer modified grout resists cracking as the wall shifts.

• Sealant: Use a penetrating sealer on the grout to prevent moisture issues behind tiles.

Don‘t skimp on quality materials for best results on uneven walls!

Step-by-Step Guide to Tiling Onto Uneven Walls

Once you‘ve prepped and leveled the wall, follow these steps closely during the actual tiling process:

1. Stir thinset adhesive thoroughly before use. Apply to a small work area strictly per manufacturer instructions.

2. Use plastic tile spacers consistently for even grout joint size. Check level every few rows!

3. Press tiles into adhesive firmly with a slight twisting motion and use a beating block on mesh backed tiles.

4. Inspect installation for hollow spots indicating poor adhesion before grouting. Re-adhere any loose tiles.

5. Let thinset cure fully (at least 24 hours) before grouting. Mix grout following package directions.

6. Pack grout tightly into joints and clean excess grout thoroughly before drying. Use sealant!

Watch closely for lippage between tiles and adjust as needed to keep your rows even despite unevenness. Having a helper to assist definitely speeds up the process and improves results.

Tiling Over Existing Uneven Tile

Sometimes you don’t want to take the time to rip out old tile and prep the wall underneath. But is tiling over uneven existing tile a good idea? Here are the main pros and cons:

Pros:

• Saves labor by not removing old tile
• Avoids repairs to subsurface flaws
• May match new grout lines with old

Cons:

• Old tile unevenness telegraphs through
• Risk of poor adhesive bond
• Can‘t identify underlying wall issues
• Irregular grout lines from unevenness

My professional opinion? Don’t do it! While suitable for small accent walls, tiling over large areas of existing uneven tile often leads to failure, especially in wet areas. Invest the time to remove old tile and properly prep for best results.

Dealing with Severe Unevenness

If facing extreme unevenness of 1/4 inch or more, beyond just minor dips and bumps, significant smoothing will be required. Here are some options:

• Cement Backerboard – Build out and level the wall by securing sheets to furring strips on studs

• Brick Veneer – Adhere thin brick sheets evenly across the entire surface to disguise flaws

• Tear Down and Rebuild – Remove wall finish, reframe with secure substrate, then apply smooth new wall

• Hire a Pro! – For major leveling projects, a professional tiling contractor is worth the cost to ensure success

Special Considerations for Inside and Outside Corners

The corners and edges of outside walls with uneven surfaces take extra finesse. Expect to do lots of test fitting and adjusting. Here are some tips:

• Use an oscillating multi-tool to carefully notch or shave bumps and high spots for tighter tile fit

• Take extra time properly leveling backerboard corners before tiling

• Mix tile from multiple boxes when tiling long expanses near corners

• Wrap tiles snuggly with 1/8” foam backing sheet before installing

• Use an edge leveling system for outlets and other obstructions

Carefully wrapping corner and edge tiles prevents cracking against uneven surfaces. Don’t be afraid to make minor adjustments to the wall itself for the perfect fit.

Troubleshooting Loose or Falling Tiles

If installed tiles become detached or start to fall off an uneven wall, moisture is the most common culprit. Make sure to:

• Routinely seal and reseal grout lines with penetrating sealant

• Address any underlying moisture in wall before retiling

• Use waterproof substrate like backerboard in wet areas

• Check for leaks, floods, condensation issues

• Re-adhere tiles using flexible adhesive after fully drying wall

Don’t just re-grout loose tiles! Bond failure due to moisture issues must be fully addressed first.

Maintaining Your Tiled Uneven Wall

Putting in the sweat equity for proper prep and installation is only half the battle. Be sure to regularly maintain your tiled uneven wall:

• Inspect annually for any cracked, loose or hollow-sounding tiles

• Re-apply grout sealant every 1-2 years for moisture protection

• Immediately address any moisture related problems

• Use gentle cleaners, avoid harsh chemicals and abrasives

• Professionally remove vs. tiling over if re-doing in the future

With proper care, your tile finish will remain beautiful for years to come!

I hope this guide gives you confidence to tackle tiling onto uneven wall surfaces. While not always quick and easy, the end result is so worth the effort! Just focus on thorough prep, quality materials and proper installation and maintenance. If you ever feel unsure about severe unevenness, don’t hesitate to call in a professional tiler. But otherwise, go for it! Here’s to successfully installing gorgeous, durable tile on less-than-perfect walls.