So you have a kitchen backsplash remodel project, or a DIY bathroom tiling job to do – what do you use to seal the tile joints? Should you apply sanded or unsanded caulk? What is the difference between these two?
Sanded caulk is made of either latex, silicone, or acrylic with sand added to it for texture and bulk while unsanded caulk doesn’t have sand. The difference between sanded vs unsanded caulk is that unsanded caulk is smoother and more suitable for joints smaller than ⅛” while sanded caulk is used for larger tile joints.
Caulk, just like grout, is a joint filler material and comes in either acrylic, silicone, or latex form. Caulk is used for protecting building joints by forming a tough, waterproof, and flexible layer above them. It’s preferred over grout for use on perpendicular tile joints, due to its high flexibility which reduces the chances of cracking.
Sanded vs Unsanded Caulk – Differences
To effectively fill in larger joints, sand is usually added to caulk and grout to give them bulk and texture. This is what’s referred to as sanded caulk. The other type of caulk – called unsanded caulk – does not have sand added to it and is much smoother.
Here’s a complete rundown of the differences between sanded and unsanded caulk, the benefits and demerits of each, and where and when to use each of them.
|Sanded Caulk||Unsanded Caulk|
|Sanded caulk is bulkier and suitable for tile joints larger than 1/8th of an inch.||Unsanded caulk has a fine texture, making it suitable for joints smaller than 1/8th of an inch.|
|Makes stronger joints because of the strong sand-bonds.||Makes less brittle and lighter joints but lasts long where there’s water.|
|Sanded caulk is not a flexible tile-joint sealing material.||Is flexible and suitable for vertical tiling jobs e.g. on backsplash and shower walls.|
|Sanded caulk can grow mold and mildew.||Is waterproof and mold resistant.|
|Best used with sanded grout.||Best used with unsanded grout.|
See also Sanded vs Unsanded Grout (Differences)
Standard, unsanded caulk is usually mold-resistant. Sanded caulk- on the other hand- is not, and can facilitate the growth of mold; which usually bears a terrible smell and poses a health risk.
Due to the presence of an impurity (sand) in sanded caulk, it’s less flexible compared to unsanded caulk, thus more susceptible to cracks.
Areas of use
Unsanded caulk can be used to fill in joints between perpendicular surfaces anywhere in the house, so long as they’re not too wide. Sanded caulk, on the other hand, is best for use on wide joints so long as they’re not in the bathroom or close to the kitchen sink.
If you have joints that are thicker than one-eighth of an inch, then you should fill them up with sanded caulk. Also, use sanded caulk if you’re using glass tiles as expansion joints for wall corners.
Finally, sanded caulk should be used whenever the tiles abutting large joints have been filled in with sanded grout. But, Is sanded caulk waterproof?
Can you use Sanded Caulk in a Shower?
While it’s possible to use sanded caulk in your shower, for instance, to seal the space around the shower pipe where it meets the wall; it’s not recommended- as sanded caulk is susceptible to cracks.
You should, in fact- use regular, unsanded caulk to fill in movement joints within the shower/bathroom- such as where the bathtub comes into contact with the wall. This is because sanded caulk has low flexibility and is vulnerable to cracking under pressure. In showers/bathrooms, this kind of pressure comes from people repeatedly stepping into and out of the bathtub.
Also, since the shower/bathroom always has moisture, it presents the perfect growing conditions for mold and mildew. Since sanded caulk is not mold-resistant, you’ll most likely end up with a mold fungus problem if you use it to seal joints in the shower.
How long does sanded caulk take to cure? Under normal conditions, it takes about 24 hours to cure. However, this may be extended depending on the caulking thickness and environmental conditions on where it has been applied.
Unsanded caulk may be in the form of silicone caulk, acrylic caulk, or siliconized, acrylic caulk. The difference between these three caulk variations lie in their ease of application and flexibility, as detailed below:
- Acrylic caulk– easiest to apply, but the most prone to shrinkage during the curing stage, leading to cracks along joints.
- Silicone caulk– most difficult to apply due to the sticky nature of silicone, but doesn’t cause cracks as it is highly flexible.
- Siliconized acrylic caulk– this type of caulk is like a compromise between the other two, as it incorporates silicone caulk’s flexibility into the easy-to-apply acrylic caulk.
Unsanded caulk is recommended for use on tight joints where tiles are abutting each other at 90-degree angles. This can be the meeting point between:
- Bathroom walls and the bathroom floor.
- Bathroom walls and the bathtub.
- Shower pipe and the bathroom wall.
- Countertops and backsplashes in the kitchen.
Unsanded caulk is also recommended over sanded caulk in areas that frequently have water- such as bathrooms and kitchens. This is because it doesn’t shrink during the curing stage, and is- therefore- unlikely to crack and re-expose the spaces between the joints.
Which caulk is better sanded or unsanded?
There’s no correct answer to this question as it depends on the thickness or the location of the joints that you want to seal. For instance, for large joints that have sanded grout, we’d recommend using sanded over unsanded caulk. Meanwhile- for narrow joints between tiles and counters that are abutting one another- you can never go wrong with unsanded caulk.
Also, if you’re working on a budget and feel that you may need a large amount of caulk to fill in large joints, then sanded caulk is the way to go! This is because sand will make the caulk bulkier to effectively fill up the spaces between the joints; consequently helping you avoid having to spend up on some more caulk products.
That- however- doesn’t mean that unsanded caulk can’t be effectively used to seal spaces between large joints; all you need are a few tweaks to your sealing method. Just stuff about three-quarters of the void between the joints with caulk backer rod foam, then seal up the remaining quarter with your standard/unsanded caulk.
Finally, use unsanded caulk for joints in the shower and kitchen since it better handles the fluctuations in terms of moisture and temperature – thus minimizing chances of cracks- in comparison to sanded caulk. Read more if you should caulk before or after sealing grout?
Remember, if you’ve got cracks on joints between adjoining surfaces that were sealed with grout instead of caulk, it would be best to first off remove the old grout before reapplying the.
Applying the caulk over the old grout just won’t get the job done, as you still won’t be able to get maximum movement from your sealant as the walls and floor tiles expand and contract with the changes in temperature.
Here is a video on how to choose best caulk
- Doug Mall, Coatings Tech: Caulking Compounds and Sealants
- The US Department of Energy: Air Sealing Your Home
- Wikipedia: What is Caulk?