Best Bathroom Caulk
You need different sealants for different bathroom jobs. What you're sealing to and if the joint bends makes the choice.
No single caulk wins every bathroom job. What you're sticking to, and whether that joint moves, decides the pick. In one bathroom you might have a tub-to-tile joint, a painted baseboard, and a window frame. Each one can call for a different sealant.
Three products handle most of what a Canadian contractor hits in a bathroom. For interior trim, baseboards, and gaps you plan to paint, that's DAP ALEX PLUS, an acrylic latex caulk plus silicone. For wet areas and exterior window, door, and siding work, that's DAP SILICONE PLUS, a 100% silicone. For moving joints and concrete, that's Tremco Dymonic 100, a polyurethane. Limits decide the job before brand does, so check each one.
What actually changes the answer
Start with the joint, not the label. A tub or shower surround bead sits in a wet area. It has to stay flexible while the tub or surround moves. A baseboard or door casing bead is dry, gets painted, and only bridges a small gap. A joint between two concrete panels, or a window perimeter, moves more and needs a sealant rated for that movement.
Then check the substrate. DAP ALEX PLUS adheres to wood, aluminum, most metals, vinyl, most plastics, glass, drywall, plaster, brick, stone, concrete, mortar, fiber cement, and stucco. But the sheet says it is not recommended for copper or copper alloys, and it will not adhere well to low surface energy plastics such as polyethylene, polypropylene, polycarbonate, and PTFE. DAP SILICONE PLUS adheres to wood, glass, ceramic, porcelain, vinyl, most plastics including PVC and ABS, aluminum, most metals, drywall, plaster, composites, fibre cement board, fiberglass, and most common building materials.
Match the product to the job
For a tub or shower surround, reach for DAP SILICONE PLUS. It is a one-component neutral cure silicone that cures to a tough rubbery solid. It is 100% waterproof and weatherproof, and the cured sealant is mould and mildew resistant. It is rain ready in 30 minutes and has a water ready time of 30 minutes. It is not paintable, so paint the substrate before you apply it if the surrounding surface needs a finish.
For trim inside the house, like baseboards or door frames, that you'll paint later, use DAP ALEX PLUS. This caulk has acrylic latex and silicone. You can paint it with latex or oil paint after 30 minutes. It's good for 40 years. But don't use it where water sits all the time, like a tub or shower joint.
If the joint moves, like between concrete slabs, or around a window that flexes, use Tremco Dymonic 100. It's a polyurethane that stays put. It handles 100% movement in one direction and 50% in the other under normal job conditions. It sticks even to damp or fresh concrete without bubbling. It works in water, but not for drinking water, pools, or wastewater.
Application limits that decide the job
Check the temperature. DAP ALEX PLUS goes on between 40°F and 100°F. Don't use it if rain or freezing weather is coming in the next 24 hours. DAP SILICONE PLUS works between -37°C and 48°C. Dymonic 100 needs 40°F to 100°F. For colder temps with Dymonic 100, see the separate cold weather guide.
Know your joint size. DAP ALEX PLUS works best in joints no wider or deeper than 1/2 inch. If it's deeper, use backer rod. For DAP SILICONE PLUS, keep the joint width to 1/2 inch (1.27 cm). If it's deeper, use foam backer rod. Backer rod sets the depth and stops the sealant from sticking to the bottom of the joint.
When it sets up is not when it's ready. DAP ALEX PLUS can be tooled in 10 minutes, is not sticky after 30 minutes, and is fully dry in 24 hours. It's ready to use in 24 hours. DAP SILICONE PLUS can be tooled in 10 to 15 minutes, is not sticky after 50 minutes, and is fully cured in 24 hours. It's ready in 30 minutes. Dymonic 100 skins over in 2 to 3 hours and is not sticky after 6 to 8 hours. Don't swap these times between products.
Common mistakes
Using an acrylic caulk in a tub or shower joint. DAP ALEX PLUS is not for continuous underwater use, and a wet surround joint is exactly that kind of service. Use a silicone there.
Painting over silicone. DAP SILICONE PLUS is not paintable. Paint the substrate before you apply the sealant, not after.
Skipping backer rod on a deep joint. Both DAP sheets call for backer rod once joint depth passes 1/2 inch. Without it, the sealant bonds to the back of the joint and cannot move the way it was designed to.
Products and next step
If you are sealing a tub or shower surround, look at DAP SILICONE PLUS. If you are sealing painted trim, baseboards, or gaps you plan to paint, look at DAP ALEX PLUS. If you are sealing a moving joint, a concrete joint, or a window perimeter, look at Tremco Dymonic 100.
If the data sheet does not settle the choice, send Cranco the product name, joint size, substrate, and whether the joint is wet or dry. That is the information needed to answer.
Can I use DAP ALEX PLUS in a shower?
No. DAP ALEX PLUS is not for continuous underwater use, and a shower or tub joint stays wet. Use DAP SILICONE PLUS, which is 100% waterproof and has a water ready time of 30 minutes.
Is DAP SILICONE PLUS paintable?
No. DAP SILICONE PLUS is not paintable. Paint the substrate surface before applying the sealant.
What is the best bathroom caulk for a moving joint?
Tremco Dymonic 100 is a polyurethane sealant with a movement capability of plus 100 minus 50 percent in typical field conditions. It is suitable for water immersion applications but not for chlorinated, potable, heavy, or waste water.