If you own a home of any kind, caulk can be your best friend. Not only can it cover a multitude of sins for the DIY’er, but it is a great sealant to protect from water damage or many other things that can damage your home..
You are looking at the caulk around your bathtub and it looks nasty! You need to recaulk in a bad way, but you don’t want to take the time to remove the old caulk. Can you put new caulk over the old caulk? You should not caulk over old caulk. It is best to remove the old caulk before applying new caulk. If you cover the old caulk with new it could continue to grow mold or mildew that was previously there.
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For a deep dive into the different types of caulk, and whether your caulk can go bad, read our article Does Caulk Go Bad.
Need More Caulk?
There are many reasons you may need to recaulk, as you could use this material in every room of your house, to include outdoors. Let’s talk about a few of them.
- Handle Drafts: Seal leaks around windows and doors to reduce drafts, cut energy costs, enhance your homes energy efficiency and decrease your carbon footprint. You can use either vinyl or acrylic latex caulk for this job. The vinyl works best in damp areas and will last 5 years, whereas the acrylic is best for dryer areas and will last up to 15 years.
- Wood Working: Measure twice, cut once may be your mantra, but no matter how careful you are you will end up with gaps in your project. Acrylic latex caulk is the solution to your problem. It fills the gaps to prepare to paint if needed and comes in a variety of colors to match the project.
- Kitchen and Bathroom Tile Touch Up: As time passes, perhaps the grout loosens or spaces open up between the tile and tub or sink. This opens the door for mold and mildew. Silicone caulk is the best for wet situations and is mold and mildew resistant.
- Getting Ready to Paint: There are always tiny holes or cracks to fill prior to painting. Painters caulk will stick to drywall, wood, brick, and drys in about an hour.
Before you begin your caulking project, you need to decide whether to remove the old caulking first. It is almost always best to take the effort to do this. Think about why you are recaulking in the first place. Some say recaulking over old caulk is like putting a bandaid on a broken leg. You are probably recaulking because the old caulk is stained or it’s shrinking and separating from the tile or tub. If it is stained, it could just be dirty, but it may be mold or mildew which is a whole different ball game. You do not want to just cover up mold or mildew and allow it to continue to grow underneath the new caulk. Caulking over mold or mildew does NOT stop it from growing. If you put new caulk over separating caulk, it will eventually break the seal of the new caulk, totally defeating the purpose.
Removing Old Caulk
As we have said, removing old caulk before applying new is the best way to go. While it takes more time to complete your project, you will definitely be happier in the long run. If your caulk is silicone, nothing will adhere to it, not even more silicone, so removing it is almost always the best bet. You can use a silicone remover for this project, just follow the directions on the product. You can also use a razor blade scraper tool. If you use this tool, hold it at a low angle and push gently to cut into the caulk. If the caulk isn’t too old and is acrylic, try softening it with isopropyl alcohol, being careful not to get this on the uncaulked surface.
When all the caulk is removed, be sure to clean the entire surface with a household cleaner, rubbing alcohol, or wire brush, and vacuum if necessary and wipe clean. You will want the area to be clean, dry, and free of any grease, dirt or chemical cleaners before you apply new caulk.
New Caulk Over Old Caulk
While it is always best to remove the old caulk before applying new, you can actually do this job without removing it. You can apply a wider strip of new caulk, covering the old line of caulk and sticking to uncaulked surfaces on both sides. You need to clean the surface of the old caulk first with rubbing alcohol, getting rid of any trace of grease or oil. Test a small area to be sure the new caulk will actually stick. If there is any oil at all, it will not stick. Apply a wider line of caulk, making sure it sticks to either side of the old caulk.
Caulk can be one of the handiest tools in your toolbox, but can only be helpful when you take the time to do it correctly. Removing your old caulk prior to adding the new caulk is always advised, but especially when you are trying to get rid of mold and mildew. If your old caulk was still in good shape, you wouldn’t need to replace it, so why would you want to keep the old caulk on and risk it causing damage to the new caulk?
How big of a gap can you caulk? About a ¼ inch. Measure the gap that needs to be filled. If it is slightly larger than ¼ inch, fill with caulk deeper into the gap, but not flush to the surface. Once the caulk is completely cured, you can put an additional bead of caulk on.
How often should caulk be replaced? With good quality caulk, about every 5 years. You obviously will want to check every couple of years for mold or mildew, or drafts coming into your home to see if you need to replace it more frequently.
Can I caulk over cracked grout? You will need to remove all grout with a grout saw prior to replacing grout with caulk. Vacuum out the area to remove every bit of grout, then apply caulk and smooth it out with the caulk gun or the back of a spoon, or even your finger.