Using Household Caulk As An Adhesive
Caulks can be used as glues... sometimes
Household caulks, including silicone, acrylic latex and polyurethane, definitely qualify as waterproof glues. They are very flexible, which makes them good for holding materials that may experience limited movement or bending... the same quality that makes them excellent for sealing joints and seams in showers, around windows, etc.
Be careful not to spread the caulk too thinly. Caulks are not designed to be used in very thin applications like wood glues, making them a poor choice for high quality woodworking.
Don't assume all caulks have good adhesive properties...
Some caulks are designed for just caulking and nothing else. Always read the label to be sure! If the product label does not say "adhesive caulk", it probably isn't!
Four of the most popular brands of adhesive caulks are DAP, Loctite "2 in 1" (formerly Polyseamseal), Phenoseal, and GE Silicone.
Limitations
Be careful to read the manufacturer's list of uses and limitations. For example, most if not all latex (water-based) caulks are not recommended for use in areas with high or constant water exposure, such as aquariums, where silicone caulks shine! Latex caulks are also not recommended for use under shower door tracks or other confined locations. This is because latex caulks need quite a bit of air exposure to dry properly. Silicone caulks undergo a chemical process that is less reliant of air, so they will set even when sandwiched between two non-absorbent surfaces.