Giovanni Valle is a licensed architect and LEED-accredited professional and is certified by the National Council of Architectural Registration Boards (NCARB). He is the author and managing editor of various digital publications, including BuilderSpace, Your Own Architect, and Interiors Place.
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For small joints, normal caulk is used. For large joints, however, and for areas where joints are adjacent to grout, sand is added to caulk to bulk it up and make sure it can fill the wider joint. The question becomes, however, whether sanded caulk is as effective a sealant as un-sanded caulk and whether that caulk needs to be sealed to prevent water leaks.
You do not need to seal sanded caulk after application. Sanded caulk is simply caulking with some texture added to it, but the sand does not change the water-resistant properties of the acrylic, latex, or silicone caulk. In fact, the chemicals in sealant may degrade caulk if left in contact for a period of time.
Sanded caulk is typically used where you are applying grout to the spaces in between tiles; since grout is just very fine concrete mixed with water, it follows that to have a seamless, aesthetic flow in your work, you want a caulk with some texture to it. Since grout will absorb and hold water, it needs to be sealed after application. Keep reading for tips on when and how to use sanded caulk in your next project!
Does Sanded Caulk Need to be Sealed?
Sanded caulk is a variety of caulk that has sand added to it during manufacturing to give it extra bulk and texture. Typically, a contractor or homeowner will choose sanded caulk when they have tile in their bathroom, and they want to match the texture of the grout when they apply caulk to the joint between a vertical and horizontal surface.
Sanding caulk can also add bulk to it to fill in joints or gaps that are wider than 1/8th of an inch. Sanded caulk is still caulk, however, so it still has waterproof qualities. Grout is sealed because it will absorb and retain water, so it needs a waterproof sealer on top to avoid mold and mildew, among the other issues that come with retained water.
Since sanded caulk doesn’t have this issue, it doesn’t need to be sealed. There are reports, however, that sanded caulk doesn’t perform as well as un-sanded caulk in terms of longevity.
What Does Caulk Actually Do?
Caulk is a rubber-like substance that comes out of a tube, applies like a gel, and then hardens to form a water-proof seal. In housing, it’s usually used in kitchens and bathrooms, as well as around windows and doors, to keep water from seeping into joints. This usually means being applied where a wall meets the floor, around the edges of sinks, tubs, and showers.
Caulk’s main job is to keep water from getting into joints, because prolonged exposure to water will weaken constructions materials as well as encourage the growth of mold and mildew, one of every homeowner’s worst nightmares. It can also be used to seal drafty windows and keep bugs out, among many other uses.
The Differences Between Sanded and Un-Sanded Caulk
While you may think the only difference between sanded and un-sanded caulk is the texture, that’s not entirely true.
Un-sanded caulk is the normal, smooth caulk you can find around the doors, windows, sinks, and showers in your house. It comes in a variety of colors and can have many materials as its base, including acrylic, latex, silicone, or polyurethane or polysulfide.
Each type of caulk is better suited for specific jobs; for instance, acrylic-based caulk is usually used around doors and windows because it can be painted and it dries hard, while silicone-based caulk is better for bathroom and kitchen applications because it isn’t degraded by exposure to water.
Sanded caulk becomes harder and more brittle than un-sanded caulk, so when used in bathroom applications where it may be exposed to water, it has a shorter life expectancy. Manufacturers make sanded caulk to match grout, and usually, the grout manufacturer will make a matching sanded caulk so the color match is good.
Most manufacturers have a wide range of colors of sanded caulk to match their own grout colors as well. Some of the most well-known brands of sanded caulk include the following:
- Custom Building Products
Most likely, the grout you get will determine what brand of caulk you get, since most have their own proprietary colors and any competitor won’t be an exact match. There is some evidence that it will crack if exposed to continuous pressure, like when you step out of a shower, and that it isn’t as mold-resistant as normal silicone caulk.
When to Use Sanded Caulk
Typically, you would choose sanded caulk for one of two reasons:
- You’ve applied grout to the tiles in a bathroom or kitchen and you want the caulk to look like the grout, while still waterproofing vulnerable joints.
- Or, you have a wide gap in a joint (greater than 1/8th of an inch) and you need to bulk up the caulk you have to make sure it bonds properly.
While sanded caulk doesn’t need to be sealed like grout, you do lose several of the benefits of regular silicone caulk if you buy the sanded variety. Because it dries much harder, it is prone to cracking. The normal silicone caulk you find around your sink or shower has some flexibility to it, allowing it to bend somewhat, especially when pressure is applied to it.
This means that if you’re stepping off of a shower step that has sanded caulk at its base, this caulk will crack and allow moisture to get in after a period of time. Since sanded caulk typically has a shorter lifespan than regular caulk, areas that experience high traffic may see it needing to be replaced more regularly. Typical caulking might last five or ten years before it has to be replaced, but sanded caulk may only last one or two years.
While you will have to apply a grout sealer to your grout to keep water out, you won’t have to do the same for your sanded caulk. It still is waterproof, although maybe not as effectively as normal caulk.
Sanded caulk is a good tool to use if you’re installing tile floors and you want to maintain the look and texture of grout as you change from horizontal to vertical surfaces, while still creating a water-tight seal at vulnerable joints.
You don’t have to seal sanded caulk to reap these waterproofing benefits, as it’s still a silicone-based product that is designed to adhere to almost any surface and create a watertight seal.
With that being said, sanded caulk does not have as long a life expectancy as the normal variety, and it is not as resistant to mold or mildew either. It will dry harder and be more inclined to crack or break since it loses much of its flexibility with the sand.
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