Installing tile outdoors comes with its own set of challenges, especially when it comes to grouting. Outdoor environments are subject to temperature fluctuations, moisture, weathering and more – all of which can be detrimental to grout over time. Proper grout selection and application is key for achieving lasting results. Here is a comprehensive guide on how to grout outdoor tile correctly.
Prep the Tile Surface
Before applying grout, the tile surface needs to be clean and free of debris. Sweep or vacuum up any loose dirt or particles. Use a damp sponge to wipe off any dust or film. Ensure the tiles are completely set and securely bonded to the surface below.
For existing outdoor tile, examine the grout lines and rake out any cracked or crumbling grout using a grout saw or rotary tool. Chip away old grout until you reach solid, intact areas. Remove all old grout residue and re-clean the tile surface.
Having a pristine surface is crucial for proper grout adhesion.
Choose the Right Grout
Not all grouts are suitable for outdoor use. Standard sanded grout is prone to cracking, crumbling and washing out when exposed to the elements.
For outdoor tile grouting, epoxy or urethane grout is highly recommended.
Epoxy Grout
Epoxy grout is extremely durable, waterproof and stain resistant. It creates a plastic-like seal within the joints. Some key advantages:
- Withstands freezing, thawing and wet conditions without cracking
- Resists mold, mildew and bacterial growth
- Won’t wash out over time like cement grout
- Provides excellent color uniformity and won’t fade in sun
- Sets firmly and offers high bond strength
- Can be used for joints 1/16″ to 1/2″ wide
Downsides of epoxy grout include shorter working time and difficult cleanup. Acid-based epoxy grout can etch certain types of tile. Be sure to check tile manufacturer guidelines before use.
Urethane Grout
Urethane grout offers flexibility and waterproofing similar to epoxy.
Benefits include:
- Remains flexible to handle expansion/contraction of tiles
- Withstands freeze/thaw cycles without cracking
- Resists staining from grease, oils and dirt
- Inhibits mold, mildew and bacteria growth
- Easy cleanup with just water while wet
- Provides UV stability – won’t fade or yellow in sun
Urethane grouts are ideal for surfaces subject to movement like wooden decks, patios and pool surrounds. Limitations are narrower joint width (1/16″ to 1/8”).
For general outdoor use on stable surfaces, epoxy or urethane grout will provide the best longevity. Both chemical grouts outperform cement.
Grout Joint Width
The width of your tile joints impacts the grout choice. Follow these guidelines:
- Tile with joints 1/16” to 1/8” wide – Use urethane grout
- Joints 1/8” to 1/2“ wide – Use epoxy grout
- Joints wider than 1/2″ – Use sanded caulk instead of grout
Using the right grout for the joint width will ensure proper fill and prevent cracking.
Grout Colors
Lighter grout colors are best for outdoor application. White or light gray blends in vs. drawing attention to joints. Dark grout absorbs heat from sunlight, leading it to crack and deteriorate faster. Stay away from black, brown or other dark shades.
Stick with light grout colors specifically intended for exterior use. Be aware that even epoxy/urethane grouts are not immune to fading or discoloration outdoors. Re-sealing annually will help maintain color.
Application Tips
When ready to grout, follow these tips:
- Work in manageable sections, about 10-20 sq ft at a time
- Apply grout release or sealer if needed to minimize staining
- Use grout float or rubber squeegee to spread grout over the surface
- Work diagonally across joints to pack grout deeply into crevices
- Let grout set slightly, then scrape off haze with a damp sponge
- Rinse sponge frequently and change rinse water often
- Avoid wiping fully wet – you want grout joints slightly damp
- Once cleaned up, allow grout to cure fully before exposure to traffic
Hot tip: If working in direct sunlight, tent shaded covering to prevent premature drying.
Always defer to manufacturer instructions for exact application and curing steps.
Curing and Sealing
After outdoor grout application, proper curing and sealing is a must:
- Cure grout minimum 72 hours before exposure to water or traffic
- Prevent rapid drying by misting or covering surface with plastic
- Seal grout annually – this is crucial to prevent water penetration, staining, and overall deterioration
- Re-apply sealer if water or oil starts penetrating grout joints
Taking steps to cure and seal grout will maximize service life outdoors.
FAQ
Here are answers to some frequently asked questions about grouting outdoor tile:
What’s the best outdoor grout?
For most outdoor uses, epoxy or urethane grout is recommended. Both provide flexibility, waterproofing and longevity that cement grout cannot match.
Can I use sanded grout outside?
Sanded (cement-based) grout is not ideal for outdoor use. It can crack, crumble and erode faster than chemical grouts when exposed to weather and moisture. Epoxy or urethane is a better choice.
How do I apply grout on an uneven surface?
On uneven surfaces, work in smaller sections and pack grout firmly into joints using a grout float or rubber grout squeegee. Wipe diagonally across tile to clean off haze and finish grout smoothly.
Should I seal outdoor grout?
Yes, sealant is strongly recommended for outdoor grout. Annual sealing will waterproof joints and prevent staining, discoloration and deterioration.
What color grout is best outside?
Lighter grout colors like white, ivory or light gray are optimal for outdoor use. Dark grouts absorb heat and are prone to faster fading/cracking.
Can I grout tile when it’s hot or humid?
Extreme heat and humidity can cause rapid grout drying and cracking. Grout in the cooler morning hours when possible, or use shade coverings. Mist grouted areas regularly to slow moisture loss.
How long does outdoor grout last?
With proper application and annual sealing, epoxy or urethane grout can last 5-10 years outdoors. Cement grout may need re-grouting every 1-3 years. Durability depends on weathering, traffic and maintenance.
Conclusion
Grout plays a vital role in finishing outdoor tile installations. Taking steps to use the right grout and apply it correctly will keep your outdoor space looking pristine. Epoxy and urethane grouts are best suited to withstand weathering and wear. Allow proper cure time, and be diligent with annual sealing. With the right techniques, you can achieve durable, lasting grout lines outside.
Grouting outdoor tile requires paying attention to details – from surface prep, to joint width, to grout selection and application. Armed with the tips above, you can tackle your exterior tiling project confidently. Carefully grouted and maintained outdoor tile will provide years of lasting beauty.