Choosing the right size notched trowel is one of the most important steps when installing backsplash tile. The trowel size determines how much thinset mortar is applied to the wall, which affects adhesion and proper coverage of the tile. With so many trowel options available, it can be confusing to know what size to use for your specific backsplash tile project. In this comprehensive guide, we’ll walk you through how to choose the proper trowel size for backsplash tiles based on tile type, size, and surface material.
What is a Notched Trowel and Why is it Used?
A notched trowel is a trowel with notches or teeth that allow it to hold and spread tile adhesive or thinset mortar as it’s applied to the wall or surface. The notches create ridges of adhesive that the tile is then pressed into. This provides maximum adhesive contact between the tile and substrate for a firm bond.
Notched trowels are used to apply thinset when installing tile so the ridges provide full coverage and support. The trowel size determines the ridge height and spread rate. Bigger tiles and certain surfaces like walls require thicker adhesive layers so larger notched trowels are used. Smaller mosaic tiles need less adhesive so a smaller trowel is ideal.
Using a notched trowel also ensures the adhesive is applied evenly. The notches control thickness so no areas end up with too much or too little thinset. Even, consistent adhesive coverage prevents tiles from coming loose or cracking from inadequate support.
What are the Different Notched Trowel Sizes?
Notched trowels come in many different sizes defined by two measurements – blade width and notch configuration.
The blade width is the width across the trowel’s flat edge in inches:
- Narrow: 3/16” to 1/2” blades – Best for small mosaics and tiles up to 4” square.
- Medium: 1/2″ to 1” blades – For standard 4”x4” up to 12”x12” tile sizes.
- Wide: 1” or wider blades – For large format tiles 12”x12” or bigger.
The notch configuration indicates the notch size, shape, and spacing. Common measurements are:
- 1/4” x 1/4” square notch – For mosaics and thin brick/stone veneer.
- 1/4” x 3/8” U notch – Standard for most tile up to 12”x12”.
- 1/2″ x 1/2″ square notch – For thick stone and large format tile.
- 3/4” x 9/16” U notch – For heavy stone/tile and extra adhesive thickness.
So a trowel’s full size denotes both blade width and notch pattern, such as “1/4″ x 1/4″ square notch, 1/2″ blade”.
In general, larger tiles require wider blades and bigger notches. Mosaics need narrow blades with small notches. Standard subway or ceramic tiles are best with a medium 1/2″ blade and 1/4″ x 3/8″ U notch.
Tile trowel size chart. Image from The Tile Shop
How to Choose the Right Size Notched Trowel for Backsplash Tiles
Choosing the proper trowel size for your backsplash depends on 3 key factors:
1. Tile Type and Size
Larger, heavier tiles require more adhesive and support than small, lightweight mosaic tiles.
- For mosaics under 2”x 2”, use a 3/16-1/2″ narrow blade with 1/4″ square notches.
- For standard ceramic subway tiles, 4″x4″ tiles, or thin brick, a 1/2″ blade with 1/4″x 3/8″ U notches is recommended.
- Large format tiles 12”x12” and bigger need a wider 1-2” trowel with 1/2″ square or 3/4″ U notches.
- Natural stone tiles that are thicker and heavier like marble, granite, or ledger panels often require a 1/2″ or 3/4″ U notch trowel regardless of tile size.
- Glass, metal or other smooth backed tiles may need a wider trowel to flatten out fully on the ridges.
2. Type of Backsplash Surface
The backsplash surface material also determines how much adhesive is needed:
- On drywall, use a trowel one size bigger notch and blade. Drywall is smoother and lacks the tooth of surfaces like concrete backerboard. More adhesive provides better contact.
- For concrete, plaster, brick, or other irregular and porous surfaces, choose a trowel with wide blades and deep notches so adhesive can fill in the spaces.
- A cement backerboard provides some natural texture so standard trowel sizes work well.
- Over existing tile that is properly prepared, you can get away with thinner adhesive layers from smaller trowels.
3. Tile Manufacturer Recommendations
Tile and adhesive manufacturers often provide trowel size guidelines which should be followed for proper warranties. Consult technical documents and product labels for the recommended trowel notch and blade.
For example, a 1/4” x 3/8” trowel may be advised for standard ceramic wall tile installation. Using a smaller trowel than specified can risk adhesion issues down the line.
Proper Techniques for Using a Notched Trowel
Once you’ve selected the right tile trowel, proper technique is key for effective thinset application:
- Hold the trowel at a 45 degree angle and use firm pressure to scrape the adhesive evenly across the surface.
- Apply only as much thinset as can be comfortably tiled before drying or “skinning” over occurs, usually around 15-30 minutes.
- Use the trowel’s flat side to flatten any high ridges or swipe away excess thinset for a uniform depth.
- Maintain a consistent notch angle and pressure as you trowel to ensure even adhesive coverage.
- Occasionally notch clean thinset ridges by drawing the trowel notches through applied adhesive.
- After setting tiles, check for full mortar contact and transfer to the tile backs to ensure proper trowel size was used.
- Be sure to clean tools before thinset dries using water and a coarse scrub brush or sponge.
Notched Trowel Options for Backsplashes
Based on the factors above, here are some recommended notched trowel sizes for common backsplash tiling scenarios:
Small Mosaic Tiles
Blade: 1/4″ or 3/8” narrow blade
Notch: 1/4″ square notch
The shallow ridges from a square notch trowel let small mosaics fully contact the adhesive. Narrow blades allow for intricate placing.
Try this 1/4″ Mosaic Trowel for tiny tiles.
Subway Tile, 4″x4″ Ceramic, Thin Brick Veneer
Blade: 1/2″
Notch: 1/4″ x 3/8″ U notch
This typical size provides enough adhesive for standard thin tile while still allowing for precision. U notches make application easy.
Use a 1/2″ U Notch Trowel for these standard sizes.
Natural Stone Tiles
Blade: 1/2″ or 3/4″
Notch: 1/2″ Square notch
Due to the thickness and weight of natural stone, a deeper notch provides extra adhesive contact and support.
Try a 1/2″ Square Notch Trowel for marble, travertine, or other stone tile.
Large Format Tile
Blade: 1″ or wider
Notch: 1/2″ or 3/4″ U notch
Oversized tiles need the coverage of wider blades and deep notches to adhere properly and prevent sagging.
Use a Large Format Tile Trowel for tiles 12″ and bigger.
Irregular Surfaces Like Brick or Plaster
Blade: 3/4″ or 1”
Notch: 1/2″ Square notch
For uneven and porous backsplash surfaces, wider blades and deep notches fill in gaps and provide maximum thinset contact.
On irregular surfaces, try a 3/4″ Square Notch Trowel.
Trowel Size FAQs
What size notch trowel do I use for subway tile?
For standard 3×6 subway tiles, a 1/2″ x 1/2″ trowel with 1/4″ x 3/8″ U notches is recommended. This provides enough adhesive for proper contact and prevents excess thinset grout lines.
What if my trowel is too small?
Using too small of a trowel can lead to poor adhesion, cracks, hollow spots, or loose tiles over time. It’s better to go slightly bigger to ensure sufficient coverage. Re-apply thinset with a larger trowel if needed.
What if my trowel is too big?
An oversized trowel may apply more thinset than necessary and create high ridges that are tough to flatten out. This can lead to uneven tile and difficult grouting. Switch to a smaller notch size if ridges become unmanageable.
Can I use a square notch trowel instead of U notch?
Yes, a square notch trowel can be used in most cases instead of a U notch of the same size. The square notch produces a thicker adhesive layer so take care not to apply too much.
What do professional tilers recommend?
Many pro tilers suggest using a U notch trowel one size bigger than technically needed. The extra adhesive capacity helps prevent thin spots and allows for back buttering of tiles if desired.
Conclusion
Choosing and using the proper notched trowel makes a big difference in the success of any backsplash tiling project. Take into account the tile type, size, and backsplash surface material and texture. Follow manufacturer guidelines for adhesive thickness. Allow enough adhesive depth for the tile to adhere firmly without excess squeeze out between joints. A quality notched trowel designed for your specific tile size and backsplash surface will lead to a durable, long-lasting backsplash installation.