How to Put Backsplash on Uneven Wall

Installing a backsplash can add visual interest and protect the walls behind a sink or stove from splatters and spills. But what if the wall surface is uneven? Putting tile or panels on an uneven wall takes a few extra preparation steps, but it is doable with some planning and patience. Here is a detailed guide on how to put backsplash on uneven wall surfaces for a professional looking result.

Assessing the Wall Surface

The first step is to thoroughly examine the wall for any imperfections that will need to be addressed before installing the backsplash. Look for:

Bumps, Nicks, and Holes

Examine the entire wall surface and take note of any bumps, nicks, holes, or irregularities in the drywall or plaster. Make sure to look closely near the edges and corners where it meets countertops, cabinets, or other walls. Any significant bumps and imperfections will need to be smoothed and leveled out.

Uneven Sections and Bowing

Use a long straightedge like a level or straight piece of wood to check for bowed or uneven sections. Place the straightedge vertically along the wall and look for any gaps where the wall surface is not flush. Make note of high and low spots. The wall surface should be even for a proper backsplash installation.


Inspect for any cracks in the wall material. Small hairline cracks can be dealt with during the preparation phase, but large gaps or cracks may indicate structural issues needing repair before installing the backsplash.

Moisture Damage

Look for any signs of water damage or leaks that may have warped the wall. Water-damaged drywall or plaster will need to be cut out and replaced.

Making notes on all the imperfections in the wall will help determine the best approach to prep and level it for the backsplash installation.

Prepping an Uneven Drywall or Plaster Wall

For minor bumps, nicks, and small holes and cracks, drywall and plaster walls just need some extra smoothing and patching to even the surface:

Sand Bumpy Areas

Use 100-120 grit sandpaper to sand down any small bumps or ridges on the wall surface. A pole sander can reach high areas. Wipe away dust when finished.

Fill Holes and Cracks

Fill any small holes, gouges, or cracks with lightweight spackle or joint compound using a putty knife. Let dry completely and sand smooth.

Skim Coat Uneven Areas

Mix joint compound to a frosting-like consistency and use a drywall knife to apply a thin, even coat over uneven sections. Feather the edges and let dry completely before sanding smooth. Allow to fully dry overnight before sanding smooth.

Prime Wall Before Setting Tile

Once smoothed and free of bumps, apply a coat of primer to create an even base layer for the thinset and backsplash tiles.

Tips for Skim Coating Drywall

  • Thinner coats dry faster, allowing more coats in a day if needed
  • Keep edges of coats feathered so transitions are smooth
  • Be patient and allow coats to fully dry between applications
  • Lightly sand each coat with fine grit sandpaper before applying the next

Properly prepping a drywall or plaster wall with sanding, patching, and skim coating ensures it is ready for the backsplash installation.

Dealing with Uneven Walls – Other Materials

Walls made from materials other than drywall and plaster may need additional work:

Wood Panel or Brick Walls

Walls with grooves or uneven brick surfaces will need a layer of cement backerboard installed to create a smooth, consistent surface for the backsplash.

Concrete Block Walls

Block walls need to be fully plastered or parged with concrete to achieve a smooth facade before adding the backsplash.

Metal Stud Walls

For thin wall framing, add a layer of 1/2″ plywood over the studs before installing the backsplash. This helps strengthen the surface and prevent flexing.

The key for any uneven wall surface is building it out to be smooth, stable, and plumb. Additional wall material layers are often needed.

How to Prep Concrete, Poured Concrete Block, and Parged Walls

Concrete-based wall surfaces can also have varying degrees of unevenness. Here is how to prep concrete for a quality backsplash installation:

Clean and Etch the Concrete

Use a degreaser to remove any dirt, oils or waxes from the concrete, then etch with muriatic acid so the thinset can bond.

Check for Bowing or Imperfections

Use a long straightedge to find any significant high or low spots. Mark areas needing repair.

Mix Repair Mortar

Mix non-shrinking concrete repair mortar to patch holes, low areas, or cracks according to manufacturer’s directions.

Fill and Level

Apply repair mortar, overfilling deeper areas slightly. Screed off excess once partly set, then trowel smooth once fully cured.

Consider Adding Cement Board

If concrete surface is still quite uneven after repairing imperfections, fasten 1/2″ cement backerboard with concrete screws to create a smooth, consistent layer for thinset and backsplash installation.

Again, the goal is to achieve a flat, stable concrete surface for a quality backsplash installation. With proper repair and preparation, concrete can be an ideal backsplash substrate.

What to Use to Level an Uneven Wall

There are a few options when it comes to materials to level and fill an uneven wall surface in preparation for a backsplash:

Joint Compound

Lightweight joint compound or spackle works well for small cracks, holes, and minor unevenness in drywall. It sands smoothly when dry.

Concrete Patching Compound

Specially formulated compounds like Mapei Planipatch or Polyblend Sanded Patch can fill concrete and masonry surfaces up to 1-1/2” thick in one application. Fast-drying.

Cement Backerboard

1/4” or 1/2” cement backerboard like Durock or Hardiebacker can be adhered over uneven substrates with thinset to create an even layer.

Self-Leveling Underlayment

Fluid underlayments like Ardex Feather Finish flow into dips and gaps to produce a flat, smooth surface after drying. Can be used on concrete, wood, or existing tile.

When selecting a leveling product, consider the material cost, labor time, dry time, and performance factors for the specific project. Consulting with experienced contractors can help determine the best solution. Properly leveling the wall surface provides the necessary flat, stable foundation for a quality backsplash installation.

How to Install Cement Backerboard on Uneven Walls

Cement backerboard is a go-to product for leveling uneven wall surfaces in preparation for tile backsplashes. Here is a step-by-step guide:

Materials Needed

  • 1/4” or 1/2” cement backerboard
  • Backerboard screws
  • Thinset mortar
  • Notched trowel
  • Fiberglass mesh tape

Step 1: Cut Board to Size

Measure the area and cut cement board to size with a utility knife. Wear eye and dust protection.

Step 2: Apply Thinset Mortar

Apply thinset mortar to the back of the cement board using a notched trowel. Cover all edges and center areas.

Step 3: Fasten Board to Wall

Press cement board firmly onto the wall surface. Fasten with backerboard screws every 8-12 inches around the edges and throughout the field.

Step 4: Tape Seams

Cover all cement board seams with fiberglass mesh tape embedded into thinset. Smooth excess.

Step 5: Seal Surface

Seal the surface of the backerboard with a drywall primer or latex-modified thinset mortar. Let dry completely.

With some careful planning and layout, backerboard can effectively level and strengthen uneven wall surfaces for proper backsplash installation.

Using Self-Leveling Underlayment on Uneven Walls

Another method for leveling uneven wall surfaces is applying a self-leveling underlayment compound:

Materials Needed:

  • Self-leveling underlayment
  • Mixing paddle & drill
  • Measuring buckets
  • Smoothing trowel
  • Spiked roller

Step 1: Dam Uneven Areas

Use foam backer rod or weatherstripping to dam very uneven spots so liquid levels properly.

Step 2: Mix Underlayment

Mix self-leveling compound per manufacturer’s directions. Only mix amount that can be applied in time allotted.

Step 3: Pour and Spread Evenly

Carefully pour underlayment. Use a trowel to spread evenly. Aid flow using spiked roller.

Step 4: De-bubble Surface

Lightly roll the surface with a spiked roller again to release any air bubbles. Smooth edges.

Step 5: Allow to Dry

Allow self-leveling underlayment to fully cure per manufacturer recommendation before installing backsplash.

With some trial and experience, self-leveling underlayments can produce a very smooth, flat surface for backsplash installations on uneven walls.

Tips for Backsplashes on Uneven Walls

Here are some additional tips to manage backsplash installation on uneven wall surfaces:

  • Only use materials designed for uneven surfaces like cement backerboard and self-leveling underlayment to fill and smooth wall imperfections. Joint compound or wood can lead to cracks.
  • Allow proper drying time for any patching materials before installing backsplash. This preventsloose tiles or cracking grout lines later on.
  • Use a premium modified thinset mortar designed for uneven surfaces when setting the backsplash tiles. This allows better adhesion.
  • Consider smaller tiles or mosaic sheets which flex better over any slight dips and bumps rather than large format tiles.
  • Use a high quality grout with polymers designed for uneven substrates. This increases strength and flexibility while reducing cracking.
  • Take time to establish proper layout lines and carefully fit and cut border tiles around edges for the best finish on uneven walls.

With careful surface preparation and using the right setting materials for the substrate, it is completely possible to achieve an attractive backsplash installation on uneven wall surfaces.

Common Problems Setting Backsplashes on Uneven Walls

Installing backsplashes on uneven wall surfaces does present some potential problems to avoid:

Loose Tiles

When thinset does not adhere properly to low spots, tiles become loose or detached over time. Ensure proper wall leveling and use appropriate thinset.

Lippage Issues

Uneven tiles with height variations can cause lippage. Check multiple tiles for uniformity and use tile leveling systems during installation.

Grout Cracking

Inflexible grout eventually cracks on uneven substrates. Use polymer-modified grout with flexibility and adhesion for uneven walls.

Moisture Damage

Excess moisture exposure can degrade patching materials on uneven walls not designed for wet areas. Use proper waterproofing.

Lack of Support

Tiles can sag or detach without proper support on uneven surfaces. Ensure adequate substrate strength.

With attention to detail in the planning and preparation stages, these common problems can be avoided for a lasting quality backsplash installation on uneven walls.

How to Put Up Backsplash on Concrete Uneven Wall

Follow these tips for installing backsplash tile on an uneven concrete wall:

Step 1: Assess Surface

Check for significant cracks, chips, bowing, or wall moisture. Repair major imperfections before backsplash installation.

Step 2: Clean and Etch

Clean away dirt, oil, and sealers from the concrete with degreaser and etch with muriatic acid so thinset adheres well.

Step 3: Level Uneven Areas

Use concrete patch compound to fill any low spots or holes. Let fully cure before proceeding.

Step 4: Install Cement Board

Fasten 1/2″ cement backerboard to the concrete using backerboard screws and thinset mortar.

Step 5: Tape Seams

Cover seams between backerboard sheets with fiberglass mesh tape and thinset. Let dry.

Step 6: Set Tile

Apply polymer-modified thinset using proper notch trowel size. Set tiles with tile spacers for consistent spacing and alignment.

Check tiles for lippage and use leveling system if needed. Allow to fully set before grouting.

Step 7: Grout Installation

Apply flexible grout designed for uneven surfaces. Wipe away excess for clean finish. Seal grout once cured.

With the right prep and modified materials, achieving a beautiful backsplash on uneven concrete is definitely achievable.

How to Put Up Backsplash on Uneven Drywall

Here is a step-by-step guide for installing backsplash tile on bumpy or uneven drywall:

Step 1: Identify Highs and Lows

Use a long straightedge to find any bowed spots or significant uneven areas on the drywall.

Step 2: Fill Low Spots

Mix lightweight spackle or joint compound to fill any low areas for a more level surface.

Step 3: Sand Bumps Down

Use 120 grit sandpaper to carefully sand down any protruding drywall bumps and ridges.

Step 4: Apply Skim Coat

If large sections are uneven, skim coat with thin layers of joint compound to level the surface. Allow thorough drying between coats.

Step 5: Prime Wall

Seal and prepare the smoothed drywall surface with a coat of primer before setting tile.

Step 6: Install Backerboard

For very uneven drywall, fasten 1/4″ backerboard over the surface to create a stable substrate.

Step 7: Set Tile on Leveled Surface

Apply polymer-modified thinset and install the backsplash tile. Use spacers for consistent grout lines and check lippage.

Proper drywall prep creates the flat, stable surface needed for quality backsplash installations.

How to Put Up Backsplash on Uneven Brick

Some special considerations for backsplashes on masonry include:

Step 1: Clean Brick Face

Use a masonry cleaner and stiff brush to remove dirt, efflorescence and any existing sealers from the brick face. Rinse thoroughly.

Step 2: Install Cement Board

Cut 1/4″ or 1/2” cement backerboard to fit the surface and fasten tightly with backerboard screws and thinset every 8-12” over the brick.

Step 3: Tape Seams

Embed fiberglass mesh tape into thinset mortar at all cement board seams to strengthen joints.

Step 4: Prime Surface

Apply primer to seal the cement board surface in preparation for thinset and tile.

Step 5: Install Backsplash

Apply polymer-modified thinset using the appropriate trowel notch size for the tile. Check for lippage and use spacers.

Step 6: Grout & Seal

Once tile is firmly set, grout the joints. Use flexible, polymer-enhanced grout for uneven masonry. Seal grout once cured.

Cement board creates the necessary smooth, stable surface for backsplash installations over existing brick or masonry.

How to Put Up Backsplash on Uneven Wood

Wood walls and surfaces also require special preparation:

Step 1: Inspect Wood Surface

Make sure the wood is structurally sound, not rotted or warped. Repair any weak areas as needed.

Step 2: Fill Imperfections

Use wood filler to patch any holes, gouges and dents in the wood surface to help create a level facade. Let dry completely.

Step 3: Sand Surface

Lightly sand the wood surface with 120 grit paper to remove any bumps or irregularities.

Step 4: Fasten Plywood

Cut 1/2” plywood panels to size and fasten tightly over the wood surface using wood screws into studs.

Step 5: Install Cement Board

Fasten 1/4″ or 1/2″ cement backerboard over plywood layer using backerboard screws and thinset mortar.

Step 6: Finish and Set Tile

Finish cement board surface with primer before applying polymer-modified thinset mortar and installing backsplash tile.

Proper substrate layers are key for backsplash success on uneven wood surfaces.

Tiling a Backsplash with Thinset Mortar

Here are some tips for using thinset when installing backsplash tile:

  • Select polymer-modified thinset for maximum adhesion on uneven surfaces. Premixed varieties are available.
  • Use proper trowel size – pick a notch size that will fully cover the tile back’s surface area.
  • Apply thinset with flat side of trowel first, then notch to desired thickness in straight, even rows.
  • Spread only as much thinset as can be tiled over in about 10-15 minutes.
  • Set tiles firmly into place in thinset. Push in a slight twisting motion. Use spacers between tiles.
  • Check bonding after a few minutes by lifting a tile to inspect thinset transfer onto back. There should be full contact.
  • Once tiles are firmly set, wait at least 24 hours before grouting according to thinset manufacturer recommendations.

The right thinset and proper application technique ensures strong, lasting adhesion on uneven wall surfaces.

Specialty Grouts for Uneven Walls

Standard sanded grout can be prone to cracking on uneven substrates. Specialty grout options include:

Flexible Grout

Contains polymers and latex additives for increased flexibility and adhesion on uneven surfaces. Less prone to cracking.

Epoxy Grout

High strength epoxy formula. Resists cracking and withstands moisture. Great for uneven tile and wet areas but slower to apply.

Furan Grout

Furan resins create an extremely durable grout. Chemical-resistant. Withstands heat and uneven substrates but requires special handling.

Always check grout packaging to ensure suitability for uneven wall applications. Grout selection can make a significant difference in the lasting quality of the installation.

Removing Existing Backsplash from Uneven Wall