With all the splish-splash that takes place in the bathroom, the grout used to fill the gaps between wall and floor tiles is normally waterproofed. Various sealants including silicone sealant and grout protector can be used to prevent water from leaking into the tiling through the grout. These sealants are usually applied when bathroom tiling is being installed. Over time, however, the grout tends to lose its ability to prevent water leakage due to normal deterioration of the sealant. Therefore, grout sealant will occasionally need to be reapplied.

If you are contemplating restoring the waterproofing ability of your bathroom wall and floor tiling by applying silicone sealant onto the grout, here is a DIY guide you can follow:

Clean your tiles.

Start by cleaning your bathroom walls and floors so as to get rid of any dirt build-up that may prevent the sealant from bonding well when it is applied. Make sure to use cleaning tools and supplies recommended by your tile manufacturer. 

Apply masking tape.

Once your tiles are clean and dry, apply masking tape along both sides of the grouted areas. This will help to make sure the edges of the sealant look straight when finished. 

Apply silicone primer.

Prior to applying sealant, you should apply primer. Applying primer coat will ensure a good bond between the substrate and the sealant. Though grout used for bathroom tiling should be waterproof, not all tiling grout is equally waterproof. Therefore, the absorbency of the grout used to install your tiling will determine how thick the primer coat should be. Allow each primer coat enough time to cure properly before applying subsequent coats. 

Apply silicone sealant.

Once the final primer coat has cured well, use a clean, lint-free cloth or rag to dry-wipe along each joint. Thereafter, grab your sealant gun and squeeze sealant along the joints. Move slowly while applying a little sealant at a time. This way, you can squeeze and smooth the sealant into place as you work. You can use your cloth or rag to remove any excess sealant that may have spread beyond the joints. Allow the sealant to cure properly before finally removing the masking tape to expose a straight sealant band stretching along the joints. 

Water infiltration through your bathroom walls and floors is never a good thing — it can cause extensive and costly structural damage to your home. You can always hire a professional to apply grout sealant for you.