Picking the Best Caulk for the Job

Ask anyone who’s been down the caulk aisle at their local home improvement store: there are a lot of options. While choosing the right caulk might feel confusing, there’s a reason there are so many types. Host Kevin O’Connor gets a primer on caulking from general contractor Tom Silva, who explains the key points so he can choose the right product for the task at hand.

The Different Types of Caulk

There are several types of caulk, each with a specific job or characteristic that sets it apart.

Latex Caulk

Latex caulk is sometimes called “painter’s caulk,” as it’s often used to finish the seams between mouldings and walls before painting. Latex is water-based, so it’s easy to clean up and takes paint very well.

Siliconized Acrylic Caulk

Siliconized acrylic caulk is often used outdoors because it’s more flexible than latex and resists tearing or cracking with weather changes. It’s still paintable, so it’s a good option for exterior siding, gaps around windows, and damp areas that need protection but would benefit from a coat of paint.

100% Silicone Caulk

Pure silicone caulk is a great option anywhere a completely waterproof barrier is required. It’s mold-resistant and highly flexible, making it a great option for extreme temperatures. It’s not paintable but does come in a few basic colors to help it blend in.

Butyl Rubber Sealant

Butyl rubber sealant offers one of the most flexible and long-lasting caulking joints, sticking to a wide variety of materials, including flashing, gutters, metal siding, vents, and chimneys. It does an excellent job of waterproofing and handles extreme temperature changes well. It comes in a few colors because it’s not paintable, and it’s important to note that it can be very messy to deal with.

How to Make a Caulk Seam Last

Tom’s trick for making sure that caulk lasts comes down to a few factors:

•   The type of material he’s caulking
•   Whether or not he needs to paint it
•   The surface preparation

For outdoor projects, Tom prefers a silicone or butyl-based caulk. However, if he needs to paint it, he’ll choose an acrylic caulk. Indoors, he’ll choose latex caulk for its paintability or siliconized acrylic for its waterproofing and paintability. In a bathroom, he’ll lean toward an acrylic or 100% silicone.

Surface preparation is just as important. Tom says new joints should be primed first to improve the caulk’s adhesion. Old joints need the existing caulk removed completely, either by scraping it off with a razor or by using a caulk-removal solution. Only then will Tom run a new bead of caulk in the joint.

Resources

Acrylic Latex Caulk aka Latex Caulk

• General-purpose caulk. Easy to clean up and very paintable. Sometimes called “painter’s caulk.”
• Best to use if you plan on painting for a seamless finish. Good for filling joints around things like doorframes, baseboards, crown molding, and interior trim. Use in dry, temperature-controlled areas.

Acrylic Latex Plus Silicone, aka Siliconized Acrylic Latex Caulk

• Still paintable and easy to use, but the silicone adds flexibility and water resistance. Also more durable where temperature changes occur.
• Good for sealing exterior siding, gaps around windows, and damp areas.

100% Silicone Sealant

• Creates a waterproof barrier and is usually mold-resistant. Durable in extreme temperatures and can handle UV rays.
• Not paintable but comes in many colors to find the right color match.
• Good for areas that are constantly exposed to moisture, such as showers, bathtubs, and sinks.

Butyl-Rubber Sealant

• Even more flexible than the silicone caulks, able to handle vibrations and material expansion and contraction. Waterproof and can withstand extreme temperatures. It’s long-lasting and stays rubbery.
• Sticky and messy to work with.
• Good for roof flashing, gutters, metal siding, vents, and chimneys.