You’ve probably worked out by now that your damaged or worn caulk isn’t going to fix itself. So, now you’re thinking that caulking over the old caulk is a quick time-saving way to deal with the problem. But, can you caulk over caulk?
You can caulk over caulk. Just make sure that the old caulk is dry, clean, and oil and dust-free. Also, apply the new caulk to extend beyond the old, onto clean caulk-free surfaces to which it can adhere. However, for best results, you should remove the old caulk before applying a new caulk.
As you can see, although you can caulk over caulk, you’ll still need to do a lot of preparation work. So, if you were thinking of just layering on the new caulk, think again. If you want to give your caulk over caulk shortcut a real chance of success, you can find out how below.
What Is Caulk Used For?
Around your home, you’ll see caulk around windows, doors, and baseboards or baths and sinks. Its job is to seal gaps.
When used to seal gaps between window and door frames, it doesn’t just hide the existence of an unsightly gap. It also provides draft and pest-proofing.
Around baths, sinks, and shower trays, caulk prevents water from escaping into gaps between these fixtures and walls. So, it’s there to prevent damp and water damage problems.
You can mold caulk to the gap you’re filling and smooth it out for a clean look. Once dried, it still retains some flexibility to accommodate some movement of the materials on either side of the filled gap.
Types of Caulk
There are many types of caulk available, but let’s focus on the two most common types you’ll come across in your home. These are acrylic and silicone caulk.
Acrylic caulk contains some latex to give it flexibility. It’s often referred to as the painter’s caulk because you can paint over it. It’s the type of caulk you usually find around window or door frames and baseboards, filling the gaps between them and your walls.
Silicone caulk is the type you usually use in damp or wet environments. For example, you’ll see it around baths and shower enclosures or kitchen sinks and countertops. It’s used wherever you want to stop water from escaping. While there are some exceptions, silicone caulk is not generally paintable.
Can You Caulk Over Caulk?
Yes, you can caulk over caulk. But it’s usually better not to do so. At least not without proper preparation. You’d also need to accept the risk that you might have to do it all again if things don’t work out.
This is especially so if you’re thinking of caulking over silicone caulk. Once it’s cured, silicone caulk won’t always provide a good bonding surface. So, the seal between the old and new may not be as strong as if you were to remove the old caulk and start afresh.
However, that’s not to say that new silicone can’t bond to old, as you can see in this video:
So, if you’re intent on putting a second layer of caulk over existing caulk, whether it’s acrylic or silicone, you can find out how in the next section.
How to Caulk Over Caulk
If you’re going to caulk over caulk, preparation is vital. So, don’t even think of taking any shortcuts here, especially if the old caulk is silicone.
Here’s what you need to do.
1. Make Sure You Clean It Thoroughly
You need to clean the old caulk and, most importantly, the surfaces on either side of it. You’ll understand later on why cleaning the surrounding surfaces is so important.
If the old caulk is acrylic, you can use soap and water on the caulk and areas on either side of it. Make sure you remove all dust, grime, and any flakes or chips of loose caulk. The best way to do the latter is with a vacuum cleaner.
You can also use denatured alcohol on the surrounding surfaces. That will remove any oily residues. However, don’t use it on the old acrylic caulk as it could soften and weaken it.
For silicone caulk, clean the caulk with a solution of one cup of bleach to ten cups of warm water. Apply the solution and leave it for about half an hour before gently rubbing it off with a sponge. Don’t be rough, as you don’t want to damage the silicone.
Avoid using soap or detergents before applying silicone caulk to any surface. Silicone caulk won’t adhere to a surface with any soap residue. Again, use denatured alcohol on the surfaces on either side of your old caulk.
2. Allow All Surfaces to Dry Completely
Caulk won’t adhere to wet surfaces. So, once you’ve cleaned the area you want to caulk, you need to dry it off completely.
Ideally, you should allow plenty of drying time. Overnight is ideal.
Before you start applying the second layer of caulk, double-check that all surfaces are dry. Don’t assume they are. If they’re not, allow more drying time. Patience at this stage will increase your chances of a successful outcome.
3. Extend the New Layer of Caulk Beyond the Old Bead
Now to the reason why cleaning the surfaces on either side of the original caulk is so crucial.
Those are the surfaces to which your second layer of caulk will adhere. That means you must make sure your new bead of caulk not only covers the old caulk but extends over the edges of the original layer.
This will give the new caulk a clean caulk-free surface to which it can bond. This is especially important when caulking over silicone around baths and showers. In those areas, the new caulk must provide a watertight seal.
Taking all these steps should give your second layer of caulk the best chance of being an effective seal. However, there’s no guarantee, and you may find you have to redo the job again sooner than if you’d removed the old caulk first.
When Should You Avoid Caulking Over Caulk?
As you’ve seen, although you can caulk over caulk if you really want to, there are a couple of circumstances in which you just shouldn’t. It’s common sense, but let’s run through them.
Don’t Caulk Over Moldy Caulk
If you have mold in, on, or behind the old caulk, there’s no point caulking over that. All that will happen if you do is the mold will continue to grow and eventually spread into your new caulk.
If the mold is beneath the caulk, you’ll probably have to bite the bullet and remove the caulk. If the mold is on top of the caulk, you can use cotton wool balls soaked in bleach to remove it before applying your second caulk layer.
This video shows you how to use this method:
Don’t Caulk Over Cracked and Broken Caulk
Another situation where you shouldn’t caulk over caulk is if the original caulk is cracked and loose. This can happen with acrylic caulk.
If you caulk over loose and broken caulk, you’ll end up with a messy finish that doesn’t have a stable base below it. So, your second layer will be prone to damage.
That’s not to say that you can’t repair a minor crack in your old caulk if the caulking on either side of the crack is stable and firmly in place. You can use the new caulk as a filler.
So, there it is. You can caulk over caulk, but it may not be as short a cut as you might be thinking. To summarize:
- Clean the surfaces to be caulked thoroughly
- Allow all surfaces to dry completely
- Your second bead of caulk must be wider than the original
Investing some time in the preparation stage should increase the chance of your second caulk layer succeeding.
So, if you’re intent on caulking over caulk, you now know how to do it. However, it won’t necessarily be a quick job, and it may only be a short-term fix.