Locate Failed or Missing Sealant
Caulk is useful at small joints where materials meet and a flexible seal is appropriate. Cracked sealant around trim, tubs, windows or doors can be renewed, but the joint should be inspected first.
A gap caused by movement, rot or water damage should not simply be filled and forgotten. The source of the opening matters more than the bead of caulk placed over it.
Remove Loose Material and Prepare the Joint
New sealant adheres best to a clean, stable joint. Loose or deteriorated caulk should be removed far enough that the new material can bond to the actual surfaces.
Moisture, mildew or damaged substrate should be corrected before resealing. Applying fresh caulk over wet or failing material can hide the condition temporarily without solving it.
Choose Sealant for the Exposure
Bathrooms, exterior trim and interior paint joints experience different moisture and movement. The sealant should be compatible with the surface and whether the joint needs paint afterward.
This page covers targeted sealing work. Larger waterproofing, window-frame repair, tile repair or plumbing leaks should be handled by their dedicated services when the joint is only a symptom.