You can install mosaic tile outdoors on a table top or as part of a fountain design if you use the right types of adhesives and grout. You also should select mosaic tiles made from porcelain or ceramic as these are the strongest tiles for outdoor use. You can find everything you need to install an outdoor mosaic tile project at a home improvement store. Choose colourful tiles for a striking display or a neutral palette for a more soothing effect.
Place the template for your mosaic design on top of a wood surface that's rated for exterior use. This would include a table made from marine-grade plywood, treated plywood, redwood, teak or cedar.
Trace around the template with a permanent marker to create your design for the mosaic. Write the designated tile colours inside each section. This will help you keep the design clear as you work.
Spread a thin layer of thinset mortar into a centre section of your design. You'll be working on small areas at a time; starting in the centre allows you to work outward and makes it easier to create a mosaic on a large space.
Scrape the thinset mortar with the notched section of your trowel. Press the mosaic tiles into the thinset, leaving about one-eighth of an inch between each tile.
Continue to work in small sections until you cover the top of the table with mosaic tiles. You may need to trim tiles with tile nippers so they will fit into a section. Tile nippers are easy to use. Just hold the tile between the nipper blades and press wherever you'd like to cut. Allow the thinset to dry.
Mix the grout according to the manufacturer's directions and use a grout float to press it into the crevices between each tile. Make sure you use grout that's rated for exterior use.
Wet a sponge with warm water and wipe it over the mosaic tiles before the grout dries. You will likely need to make more than one pass to completely remove the grout from the tiles. Failure to remove all of the grout will result in a cloudy, dull mosaic.
Add grout sealer to the surface within three days. Follow the manufacturer's application directions.