Outdoor tiled surfaces are a popular choice for patios, pool decks, and other exterior spaces. However, when installing tile outdoors, it’s important to plan for expansion and contraction of the tiles caused by changes in temperature. This is where expansion joints come into play.
Expansion joints are gaps purposefully left between sections of tiled surface to allow room for the tile to expand and contract without causing damage. They help prevent cracks, bulging, and other issues. Expansion joints are a critical component for success when tiling outdoors.
Below we’ll discuss everything you need to know about outdoor tile expansion joints. We’ll cover what they are, where they’re needed, how large they should be, and how to install them properly. We’ll also provide tips for choosing the right expansion joint filler material.
What Are Outdoor Tile Expansion Joints?
Outdoor tile expansion joints, also sometimes called control joints, are spaces intentionally left between sections of outdoor tile. They allow the tile area to expand and contract with changes in temperature without causing damage to the tiled surface.
As the weather warms up, the tiles expand slightly. As things cool down, the tiles contract. Without room to move, the tiles can crack, lift up, or buckle against each other. Expansion joints provide space for this movement.
Expansion joints are typically placed at regular intervals across the tiled area, dividing it into different sections. The joints run the full depth of the tile, mortar bed, and concrete subfloor or membrane. This allows each section to expand and contract independently without affecting surrounding areas.
Where Are Expansion Joints Needed for Outdoor Tile?
Expansion joints are an essential component of any outdoor tile installation. They should be incorporated in the following locations:
- Over crack isolation membranes: Membranes are often used over concrete subfloors prone to cracking. The membrane prevents cracks from transferring up through the mortar and tile. Expansion joints should be placed over all seams and edges in the membrane.
- Where the tile abuts restraining surfaces: Restraining surfaces include foundations, columns, curbs, stairs, fixtures, drains, and more. These areas prevent the tile from expanding/contracting freely, so expansion joints are needed where tile meets restraining surfaces.
- At all inside and outside corner: Expansion joints should be placed at any inside and outside corner in the tile layout.
- Over construction/cold joints: Cold joints are seams between adjacent concrete pours or sections that were poured separately. Place expansion joints over any cold joint.
- Around penetrations: Anywhere a pole, pipe, electrical conduit, or other item penetrates through the tile, leave an expansion joint spacer around it.
- To divide large spans into smaller sections: Large open spans of tile should be divided into sections using expansion joints. See the recommended spacing in the next section.
How Far Apart Should Outdoor Tile Expansion Joints Be Spaced?
For most outdoor tile projects, expansion joints should be placed every 8 to 12 feet in each direction. This divides the tile field into a grid pattern with sections approximately 8 by 12 feet or smaller.
However, the exact spacing can vary depending on factors like:
- Climate and expected temperature fluctuations
- Overall tile installation size
- Type of tile and substrate
Here are some general spacing guidelines:
- Up to 150 sq ft area: Expansion joints every 8 to 10 ft
- 150 to 400 sq ft: Space joints every 8 to 12 ft
- Larger than 400 sq ft: Joints every 6 to 10 ft
Areas with greater temperature swings may need joints spaced more frequently, such as every 8 feet. It’s better to err on the side of caution with closer spacing than necessary.
Each section should have a length to width ratio of no more than 1.5 to 1. For example, 5 feet by 7.5 feet or 12 feet by 18 feet. Avoid creating long, narrow sections.
Finally, you can also match expansion joint placement to the underlying substrate seams and joints. For example, follow control joints in concrete below the tile.
What Width Should Outdoor Tile Expansion Joints Be?
The expansion joint width is also an important factor. Joints should be a minimum of 3/8 inch wide. In very hot or cold climates, a 1/2 inch width may be recommended.
Wider tiles require slightly larger expansion joints. Follow these guidelines:
- Tiles under 12 inches wide: Use 3/8 inch joints
- 12 to 18 inch tiles: 1/2 inch joints
- Over 18 inches wide: Use 5/8 inch joints
The joint width should match the overall movement expected in the installation based on climate, substrate, and tile type.
How to Install Expansion Joints for Outdoor Tile
Installing outdoor tile expansion joints correctly is key to their effectiveness. Here is an overview of how to install expansion joints:
Plan Joint Placement
First, map out the control joint placement based on the guidelines provided above. Mark their locations.
Leave a Gap During Tile Installation
Do not tile across planned expansion joint locations. Leave a gap equal to the full depth of the install.
For example, with a typical mortar bed install, leave a 3/8″ gap all the way through the mortar to the waterproof membrane or concrete below.
Install the Expansion Joint Material
Once the tile is installed and grouted up to the joint, install backer rod and sealant into the gap. This creates the flexible expansion joint.
Backer Rod
Insert an appropriate diameter polyethylene or EVA foam backer rod into the joint, leaving 1/4 to 3/8 inch space at the surface for the sealant.
Sealant
On top of the backer rod, install a flexible polyurethane sealant designed for expansion joints. Follow the product instructions. Tool the sealant neatly and allow it to cure fully.
The sealant absorbs the expansion and contraction movement so it doesn’t stress the tile.
Choosing the Right Expansion Joint Filler Materials
The filler material inside expansion joints plays a critical role in allowing proper movement. Use quality materials suitable for the installation.
Backer Rod
Polyethylene or EVA foam backer rod is stuffed into the joint up to just below the surface. This positions and supports the sealant correctly.
Choose a diameter approximately 25% wider than the joint gap so it fits tightly when compressed into the space. Don’t skimp on backer rod installation.
Sealant
On top of the backer rod, fill the remaining 1/4 to 3/8 inch with a flexible polyurethane sealant designed for expansion joints. Silicone and latex sealants don’t perform as well long term.
Make sure it meets specifications for the expected joint movement. Read product information carefully.
Pre-Formed Joints
PVC vinyl and rubber/EPDM pre-formed expansion joint strips are also available. These suit some applications but limit total movement compared to backer rod and sealant.
Tips for Proper Expansion Joints in Outdoor Tile
Proper installation of outdoor tile expansion joints involves attention to some important details:
- Install joints in straight lines for the best visual appeal.
- Ensure joint depth spans the entire tile assembly, never just partway through.
- Leave a consistent gap width based on tile size and climate.
- Tightly compress backer rod 25% wider than the joint space.
- Use sealant compatible with the tile and finish materials.
- Tool sealant neatly with a rounded profile, flush with the tile.
- Allow sealant to fully cure before grouting the remaining joints.
- Clean and maintain joints regularly to maximize lifespan.
Problems Caused By Lack of Outdoor Tile Expansion Joints
Neglecting expansion joints in an outdoor tile installation can lead to major problems, including:
- Cracked, broken, and loose tiles
- Buckled and lifted tiles
- Uneven tile due to some rising or dropping
- Tile grinding against each other causing damage
- Compression of mortar bed or substrate
- Cracks extending through grout joints
- Water intrusion leading to damage below
Repairing issues caused by inadequate expansion joint planning can mean replacing significant tile, mortar, and waterproofing. It’s much cheaper to include proper joints during the original install.
Design Considerations for Outdoor Tile Expansion Joints
You can customize expansion joints to integrate into the design aesthetics of your outdoor tile space.
Location
Aligning expansion joint placement with design details like the layout, format, pattern, visual breaks, and traffic flow can make them less conspicuous.
Visual Contrast
Using joint materials in a color that contrasts or blends with the tile colors influences appearance. Consider black, gray, tan, or bright white sealants.
Decorative Joints
For a decorative look, pre-formed expansion joint profiles are available with rounded, beveled, or other shapes. Decorative metal strips can also span joints.
Continuous Flooring
Minimize expansion joint visual prominence by using the same flooring material on both sides. This avoids abrupt material transitions.
Conclusion
Properly designed and installed expansion joints are crucial to outdoor tile installation success and longevity. They accommodate the movement inherent in exterior tiling and prevent common problems like cracking and buckling.
Be sure to incorporate expansion joints in all the necessary locations, with proper spacing based on project details. Use quality joint filler materials suited for expected expansion and contraction. Pay close attention to complete joint depth and proper sealant use.
With careful planning and execution, the outdoor tile expansion joints will perform well for years while remaining subtle and complementary to the tile design. This prevents expensive repairs down the road. Discuss expansion joint planning with your tile installer before beginning an outdoor tile project.
Frequently Asked Questions About Outdoor Tile Expansion Joints
Outdoor tile expansion joints are an important part of exterior tile installations. Here are answers to some frequently asked questions about them:
What is the purpose of outdoor tile expansion joints?
Expansion joints provide space for outdoor tiles to expand and contract with temperature changes without causing damage like cracking and lifting.
Where are outdoor tile expansion joints needed?
Joints are required at seams in crack isolation membranes, restraining edges, inside/outside corners, cold joints, penetrations, and to divide large spans into sections.
How far apart should outdoor tile expansion joints be spaced?
General guidelines are every 8 to 12 feet, with closer spacing on larger installations and wider temperature swings. Sections should have a 1.5:1 length-to-width ratio.
What size should outdoor tile expansion joint gaps be?
A minimum 3/8 inch wide gap is recommended, increasing to 1/2 inch for very large format tiles or greater climate variation.
What materials fill outdoor tile expansion joints?
Polyethylene or EVA backer rod is stuffed into the gap, covered by a layer of flexible polyurethane sealant suitable for expected movement.
Why are properly installed outdoor tile expansion joints important?
Correct expansion joints prevent cracked, buckled, and broken tiles. They allow the installation to handle movement caused by temperature fluctuations.
Do outdoor tile expansion joints affect aesthetics?
Joints can be aligned with the layout design and made less visible. Decorative joint materials and continuity of flooring material also minimize impact.
How can I prevent expansion joint problems in outdoor tile?
Carefully plan joint placement, size, and materials. Install completely through all layers and use quality backer rod and sealant. Maintain sealant over time.
Can missing expansion joints be added later to an existing outdoor tile installation?
It is difficult to retrofit expansion joints properly compared to incorporating them during the original install. Damage may already exist without joints.
Key Takeaways
- Outdoor tile expansion joints are essential in exterior tile installations to accommodate temperature related movement.
- They should be installed where tile abuts restraining surfaces, over crack isolation membranes, at inside/outside corners, etc.
- Typical joint spacing is 8 to 12 feet based on project size and climate swings.
- Minimum joint width is 3/8 inch, increasing for larger tiles or greater movement.
- Joints must span the full depth of the tile assembly.
- Backer rod supports flexible polyurethane sealant designed for expansion joints.
- Omitting expansion joints risks cracked, buckled, and lifted tiles. They’re cheaper to include initially than repair later.
- Aligning joint locations with the layout, using continuous flooring, and choosing joint colors can minimize appearance.
So in summary, properly incorporating outdoor tile expansion joints is a vital part of exterior tile installation success. Careful joint planning, proper materials, and correct installation techniques will keep your outdoor tile looking great for years to come. Let me know if you have any other questions!