Removing the old caulk and replacing it with a new bead of caulk instead usually creates a better seal. However, you can effectively caulk over caulk as long as the bottom layer of caulk isn't damaged or moldy. The old caulk should also be clean, dry, and free of oil for the best adhesion.
You can recaulk over old caulk, but you should never do it.
Our recaulking experts will remove every bit of your icky, failing caulk. Then, they will add an anti-mold treatment to eliminate mold and mildew and fight future mold and mildew growth. They will apply a 100% silicone caulk, which resists shrinking over time.
The old caulk must be removed to properly treat and seal the area, so it does not happen again. The old caulk may have deteriorated due to age, decomposition, or the wrong type of caulk being used. We often find that silicone caulks were used to seal wood joinery or checks.
Can I apply a second bead of silicone sealant in the shower. First application completed 24 hours ago? It is fine to put another layer of silicone over an existing bead. The main consideration to remember is if the old bead is not fully cured you do not want to break the skin it has formed.
Never apply new silicone sealant over old sealant as, in most cases, the old sealant would have fallen away or split meaning that, no matter how much new sealant you apply, the leak will persist. Not to mention, applying a new sealant over old will look incredibly messy and unappealing.
While new, freshly applied silicone can be applied & will bond to old silicone – the bond isn't as strong as if it were applied to a clean surface.
A minimum 1/4" joint width is recommended. Wider joints accommodate more movement than narrow joints.
Typically, properly applied caulk in an indoor location should last around five years. However, other signs aside from age will indicate you need to remove the caulking and replace it. Even if your caulk does not show indications of wear, invisible damage and stress may compromise its effectiveness over time.
Consider attempting to dry the caulk before removing it. Technically, silicone caulk cures rather than dries and it requires moisture in the air to do so.
Silicone caulk is excellent at water sealing and flexibility so it has its place in construction. There are two main places it never should be installed, wood or any painted surface.
Caulk Bead Cracking
The movement and/or change in joint size is a result of moisture reduction and shrinking of the wood fibers and, most commonly, it results in hairline cracks in caulk beads and painted joints, as well as separation in the panels of doors.
Budget at least 3 to 12 hours for these products to dry and a full 24 hours to cure. For latex-based products, 24 hours is also recommended before water exposure. Polyurethane caulks can take up to 10 days to cure fully.
Applying a new layer of caulk to an old layer of caulk isn't recommended, but it is doable if the old caulk is still in relatively good condition. Damaged, cracked, and worn caulk won't provide a firm surface for the top layer of caulk, often leading to cracks and damage in new caulk.
Gaps up to 1/4″ inch in size can be caulked in the usual manner, without any concerns. If the gap is larger than a 1/4″, you will want to install a foam backer rod into the joint, prior to caulking.
Expandable foam caulk is a better choice for sealing larger gaps and holes.
Before replacing any silicone or caulk you need to get rid of as much of the old as possible. A poorly prepped surface with old sealant left behind is not what you want. The new silicone or caulk won't adhere as well, won't last as long and won't be as watertight.
Removing sealant residue will help to prevent the growth of mould. It's also an essential step before applying any new sealant; the new sealant won't adhere unless the surface is clean and dry. Before you get started: Check out UniBond's full range of tools and accessories for removing silicone sealant.
Pulling keeps the nozzle from bumping against rough spots and makes for a smoother bead. But some say pushing the caulk ahead of the nozzle does a better job forcing the caulk into the crack evenly, as long as the surface is smooth enough to allow for it.
We do not recommend using caulk to fill nail holes.
The downside of using caulk to fill nail holes is that caulk is not sandable, so you can get it as smooth as wood filler or spackle. Caulk is also fairly messy, so it's a risk to use caulk to fill a small nail hole.