Although tile caulking manufacturers do not require caulking installation to be done before or after grouting is performed in a shower, caulking before grouting a shower has significant downsides. Due to several factors, grouting first for the do-it-yourselfer is the recommended course of action.
Reasons for Grouting First
Due to its impervious, water-resistant properties, grout does not adhere to caulking. Therefore, grouting after caulking may produce areas that are not sound or areas where the gout is not bonded to the walls. The purpose of caulking in your shower is to protect against moisture and expansion. The do-it-yourselfer attempting to caulk the necessary areas in a shower before grouting will find the job difficult. More appropriately, grout first, leaving the grout lines open and clean where caulking will be applied and waiting 24 hours to do so.
Where to Caulk in a Shower
In addition to caulking shower fixtures, experienced tile setters caulk-in all changes in planes in showers including corners, surface edges and wall-to-floor intersections. Doing so protects against moisture-related issues and common expansion cracking associated with these areas. Leave these areas grout-free, clean and dry before caulking them at least 24 hours after grouting.
Caulking dries quickly -- often in less than 30 minutes -- called "tack" time in the industry. The key to effective caulking installation is to avoid applying too much caulking to the installation area and to quickly clean the product off the surface of the shower tile. Caulking that is left for too long on tile is unworkable and will have to be removed. Experienced tile setters apply masking tape to the surface of the tile before caulking.
In addition to providing a good color match for the grout, modern lines of caulking contain antimicrobial agents that prohibit mold and mildew formation caused by moisture. Leave these areas grout-free, dry and clean so that you can apply caulking to them 24 hours or more after grouting.
The caulking used in your shower can be used to adhere fixtures and loose tile but is not recommended for the installation of grab bars. In addition to its anti-mold and effective sealant qualities for your shower, caulking is stain resistant. Grout color matches are available in either sanded or nonsanded. Sanded caulking is recommended for matching showers with sanded grout; nonsanded caulking is recommended for showers with nonsanded grout.