How to Install Tile Floors Outdoors – An Overview Tutorial

In this section, we provide you with an overview of how ceramic, porcelain, or stone tile can be used in exterior patios, walkways, porches. Generally, ceramic, porcelain, or stone tile can be installed over suitable substrates in exterior locations, including mortar beds over concrete slabs and directly onto concrete slabs. These substrates must be structurally sound, meet deflection requirements, and meet on-plane requirements.

The biggest difference between indoor and outdoor tile installations is that outdoors your installation will be subject to mother nature – in other words, the unexpected. For that reason, it’s critical that you properly take into consideration mandatory expansion joints, moisture considerations, and thermal demands. If you don’t, you will encounter failures.

Given how much variation is possible – based on the project, the location and the materials used – this do it yourself or how to section will highlight what you need to consider so you don’t encounter installation issues. You’ll find an explanation and images highlighting the most common failures below.

As always, follow the Manufacturers’ recommendations for all the products you plan to use in exterior tiling projects.

What can happen when you install tile outdoors improperly
When you don’t take into account expansion joints in an outdoor tile installation, disaster can happen! In this section, we share with you examples of what can happen when you install tile outdoors improperly. All of the images below are of real failures.

Pay Attention to Expansion Joints
Expansion joints are mandatory and relate directly with the thermal demands of the materials and the location’s environment.

Since exterior tile-work will be exposed to the elements, the tile-work will expand and contract more than interior protected tile-work. Therefore expansion joints are necessary every 8′-12′ in each direction. These joints must proceed through the tile work.

Pay Attention to Water Absorption Rates
Another thermal demand relates to the area of freeze/thaw. In colder climates, the action of the freezing and thawing temperature can cause tile installations to fail. When excess moisture inside of a set tile freezes and then thaws, pressure builds to a point where tiles can spall and fracture. This situation relates directly to the water absorption rates for the tile selected.
Be sure to select a tile recommended for use in areas subject to freeze/thaw conditions. For example, certain tiles in the impervious water absorption class (less than .5% water absorption) may be suitable.

Tile with a high water absorption rate should not be selected in areas that have freeze/thaw conditions.

Pay Attention to Efflorescence
Moisture considerations also relate to the problem of efflorescence. Efflorescence is the stubborn powdery residue that commonly collects in grout joints when the surface dries. The powdery residues are soluble salts that are brought up through the tile work from the substrate below through hydration. The hydration is simply the evaporation of the water brought to the surface that deposits the salts.

Ideally, the concrete slab would be constructed in such a way to minimize the water absorption. This is accomplished in two ways. First the required slope to completely drain the surface water should be required. Then the slab should have the required drainage below. This is accomplished with a gravel base below the slab to facilitate drainage.

These requirements need to comply with federal, state, and local building codes.

Pay Attention to Water Absorption into Concrete Slabs
Unfortunately, many exterior floor tiling takes place on slabs that already exist. In this case, certain precautions can be taken to minimize the affects of water absorption into the slab. For example, the edges of the slab can be treated with a waterproofing membrane below ground level. Also, sources of water like sprinklers can be repositioned to minimize surface water.

When a project is desired on existing concrete slabs such as patios and walkways, the suitability of the existing concrete is the issue. Tile should not be placed on existing concrete that has structural defects, is not on-plane within ¼” in 10 feet, is not sloped to provide complete surface drainage, and slabs that do not have the required expansion joints.

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A word on expansion joints in existing concrete slabs: All expansion, control, construction, cold, and seismic joints should continue through the tile-work. This includes perimeter joints and where the floor meets vertical surfaces.

If the existing concrete slab is not suitable for the installation of tile directly on its surface, another method must be chosen or the slab should be replaced to allow the project to proceed.

At The Tile Doctor® we recommend Starlike Outdoor Grout for all of your outdoor needs.

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